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New Paradigms in the Treatment of
Small Bowel Obstruction
urgery in the 21st century has seen the development of a host of excitingechnological and management innovations such as minimally invasiveurgery, endovascular treatment in vascular disease, endoscopic proce-ures that require no incision, and potent and effective new medicationshat have altered the natural history of some surgical diseases. Oneisease that has changed very little in its incidence, natural history,reatment approach, and preventability is small bowel obstruction (SBO).mall bowel obstruction remains a common and difficult problemncountered by all surgeons who operate in the abdomen. Given itsommon and serious nature, it is surprising that so little progress has beenade in preventing and treating it when it occurs. Nevertheless, over the

ast 15 years, some modest progress and advancements have been maden its treatment, which will be the focus of this review.In Wiseman’s1 review of the topic, he noted that Hunter knew aboutBO in the mid 1700s and described a case associated with adhesions,eritonitis, and infection. In 1842, Bryant reported a fatal case of bowelbstruction caused by adhesions. Both Muller and Malcolm describedsing salt solution to “float the intestines” and prevent adhesions in 1886nd 1889 respectively.1 By 1932, adhesions accounted for 7% ofntestinal obstructions in the United Kingdom, and by 1934, Mosseported that 27% of intestinal obstructions in the United States were dueo adhesions2 (Table 1).

cope of the ProblemSmall bowel obstruction remains a huge problem in the United States

oday. Bevan’s review found that 1.9% of all hospital admissions wereue to bowel obstruction.3 Menzies and Ellis identified 0.9% of 28,297dmissions over 25 years due to intestinal obstruction,4 and Irvin revealedhat 3.5% of all emergency admissions that lead to laparotomy were fordhesions.5 Menzies and Ellis confirmed that 3% of all laparotomies are
erformed for adhesive obstructions alone.4 In the United States in a
urr Probl Surg 2012;49:642-717.011-3840/$36.00 � 0ttp://dx.doi.org/10.1067/j.cpsurg.2012.06.005

42 Curr Probl Surg, November 2012

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ecent year, 948,000 hospital days of care were required for treatment ofBO.6 The same study suggests that Medicare alone is paying $3.2 billioner year for treatment of SBO, and currently there are 117 hospitalizationser 100,000 people for treatment of bowel obstruction.6 In severalountries in Europe, the medical costs for SBO were greater than the costsor gastric cancer and almost as much as for colon cancer.7,8 Althoughnitial studies suggested that the increased role of minimally invasiveurgery did not appear to have significantly reduced the incidence ofdhesive SBO, more recent studies suggests that SBO incidence is lowern patients who undergo a minimally invasive procedure. Clearly, givenhe magnitude of this problem, finding a prevention for or cure of thisostly and frustrating complication should be a priority for Americanedicine.

tiology of SBOAny discussion of SBO mandates a discussion of adhesions and the role

hey play in the disease. Although adhesions rarely lead to obstruction ofhe large bowel, they account for more than 70% of all SBOs.2 A reviewf the literature regarding the etiology of SBO confirms that in the Unitedtates, adhesions constitute the major source of SBO by a large mar-in9-12 (Table 2). Other causes of SBO include hernia (most common

ABLE 1. History of small bowel obstruction

Date Event

2500 BC Ancient Egyptians describe adhesions440 BC Pleural adhesions described in Talmud1750 AD Hunter describes adhesions due to peritonitis1842 AD Bryant describes fatal bowel obstruction1932 AD Adhesions cause 7% of SBO in United Kingdom1934 AD Adhesions cause 27% of SBO in the United States

BO, small bowel obstruction.

ABLE 2. Small bowel obstruction in the United States

Author Year

Cause (%)

NumberAdhesions Hernia Cancer

layforth9 1970 54 23 9 111aws10 1976 69 8 10 465tewardson11 1978 64 24 7 238izer12 1981 74 8 9 405

ause of SBO in undeveloped countries), cancer, inflammatory bowel

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isease, intussusception, radiation, endometriosis, infection, and foreignody.In patients with a “virgin abdomen,” the most common cause of bowelbstruction is incarceration of small bowel in a hernia. Inguinal, femoral,entral, or umbilical hernias can be the source of obstruction and aresually fairly obvious on physical examination. An elderly patient with avirgin abdomen” who presents with SBO should be evaluated for anbstructing cancer if no hernia is detected.

lassification of SBOSmall bowel obstruction may be classified in a variety of ways, and a

exicon unique to SBO has developed over the years (Table 3). Smallowel obstruction may be classified as complete vs. partial, high grade vs.ow grade, simple vs. closed loop, high vs. low, mechanical vs. ileus, andhronic vs. acute. Complete SBO is characterized by significantlyistended bowel associated with failure to pass stool or flatus and lack ofir in the distal small bowel and colorectum. Partial SBO tends to bessociated with less dramatic small bowel distention, evidence of flatusnd/or stool passage, and radiologic evidence of gas throughout the entireowel. Complete SBO virtually always leads to operative intervention,hereas partial SBO can often be conservatively managed with closebservation via serial examinations and abdominal radiographs.A high-grade SBO is characterized by significant bowel distention, little

o no flatus passage, abdominal pain, and often an impressively distendedbdomen. A high-grade SBO has little likelihood of resolving withonservative management. A low-grade bowel obstruction features muchess abdominal distention, some passage of flatus and stool, and much lessain and discomfort. It frequently resolves with watchful waiting. Aimple bowel obstruction is defined as SBO in which the bowel isccluded at a single point along its length, whereas a closed loop

ABLE 3. Lexicon of small bowel obstruction

Less serious More serious

Partial CompleteLow grade High gradeSimple Closed loopLow HighIleus MechanicalChronic AcuteIntrinsic Extrinsic

bstruction is defined as an obstruction in which both the afferent and


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fferent portions of a single loop of bowel are occluded by a constrictiveesion (Fig 1). Because the blood supply of a closed loop is often alsontrapped by the constrictive band, loss of blood supply to the loop isikely with the subsequent development of strangulation and bowelecrosis. That rarely occurs with simple obstruction. For that reason,losed loop obstruction is much more dangerous than simple and shouldirtually always be treated operatively when diagnosed.A high SBO is the one that occurs very proximally in the jejunum,hereas a low SBO is found in the distal ileum. The former is associatedith epigastric distention and high nasogastric (NG) tube outputs that areilious, whereas the latter is characterized by global abdominal distentionnd more turbid, feculent, NG output.Mechanical SBO is defined as lumen occlusion by a physical pathologic

esion. Conversely, ileus is a functional obstruction caused by a range ofisease processes that have the effect of paralyzing the bowel so that noropulsive motor activity occurs. Paralytic ileus uncommonly requiresperative treatment and usually resolves when the etiologic diseaseesolves. Chronic SBO is characterized by multiple low-grade obstruc-

IG 1. Artist’s conception of a closed loop obstruction caused by a single adhesive band. (Reprintedith permission from Lawrence P, Bell R. Essentials of General Surgery (ed 3). Hagerstown, MD:

ippincott Williams & Wilkins, 2005.)

ions over a period that cause multiple ER visits and clinic assessments


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ut usually do not result in immediate operative intervention. Acute SBOevelops abruptly and usually with no antecedent history and, if nopontaneous resolution occurs, is more likely to require operation thanhronic SBO.Finally, SBO may be caused by extrinsic lesions or intrinsic processes.xtrinsic lesions cause SBO much more frequently than intrinsic ones.ommon extrinsic obstructing lesions include postoperative adhesions,ernias, endometriosis, metastatic cancer, lymphoma, volvulus, andbscess. Intrinsic diseases causing obstruction include Crohn’s disease,umors, radiation injury, hematoma, and intussusception.

athophysiology of SBO and Adhesion Formation

dhesion FormationAbdominal adhesions are abnormal fibrous connective tissue bands that

orm between intestines, organs, or tissue in the abdominal cavity that areormally separated.13 The adhesions may be congenital or acquired, theatter usually because of infection, inflammation, or abdominal surgery.

ost intestinal adhesions are caused by trauma to the peritoneum fromrevious operation (60% to 70%), and adhesions are the leading cause ofntestinal obstruction in North America. Typical injuries to the perito-eum at the time of operation that could cause adhesions includencisions, suturing, abrasion, ischemia, desiccation, and cautery.14

Adhesions after abdominal surgery are part of the normal healingrocess for peritoneal injury. The early balance between fibrin depositionnd degradation (i.e., fibrinolysis) seems to be the critical factor indhesion formation. Fibrin deposition at the surgical site is a requirementor adhesions to form. If fibrinolysis proceeds unimpeded, formation ofostoperative adhesions is greatly reduced; unfortunately, many vari-bles, including operation and anesthesia, impair this important step.13

The purpose of this section is to review the biochemical and cellularrocesses that lead to adhesion formation. A description of currentntraoperative strategies available to the surgeon to prevent postoperativedhesions is presented in the last section of this monograph.

iological Pathways That Lead to Adhesion FormationAdhesions form in response to an injury to the peritoneum in the spaceetween the parietal and visceral peritoneum. Large and small peritonealefects heal at the same rate, suggesting that healing is a field phenom-non and not centripetal like wounds in the skin (Fig 2). The outer
embrane of the peritoneum is lined by a layer of mesothelium that

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overs the surface of the peritoneal cavity and the intra-abdominalrgans15 (Fig 3). Mesothelial cells produce and secrete factors that haven effect on inflammation, peritoneal wound healing, and adhesionormation.16,17 Adhesion formation begins with trauma to the peritoneumnd the induction of a generalized peritoneal inflammatory response (Fig). As a component of the response to injury and the coagulation cascade,fibrin-rich exudate accumulates on injured peritoneal surfaces.18 This

brin-rich matrix is capable of forming permanent attachments oradhesions” between serosal surfaces within the peritoneal cavity if notesolved.19,20 Normal peritoneal healing and regeneration occurs if thebrin-rich exudate is resolved by the normally active, peritoneal fibrino-

ytic system. However, abdominal surgery often suppresses peritonealbrinolytic activity primarily by decreasing peritoneal tissue plasminogenctivator (t-PA) levels and increasing plasminogen activator inhibitor-1PA-I) levels18 (Fig 5).Both adhesion formation and adhesion-free epithelialization areathways of peritoneal wound healing. The injury of the peritoneum

IG 2. Healing of a peritoneal injury or defect is a field phenomenon and does not involve woundontraction as seen in skin wounds. Therefore, healing of large and small peritoneal wounds occurst the same rate, as illustrated in this figure. (Reprinted with permission from DiZerega GS, CampeauD. Peritoneal repair and post-surgical adhesion formation. Hum Reprod Update 2001;7:547-55, byermission of Oxford University Press.) (Color version of figure is available online.)

ay be inflammatory, infectious (as with diverticulitis), or surgical,


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nd the injury may include exposure to intestinal contents. The healingttempt begins with the formation, through coagulation, of a fibrin-ich exudate through which mesothelial cells can migrate and accom-

IG 3. Electron micrograph of widely spaced, loosely attached mesothelial cells of the peritoneumssuming the appearance of cotton balls. (Reprinted with kind permission of Springer Science�Businessedia from DiZerega GS, ed. Peritoneal Surgery. New York: Springer-Verlag, 2000.)

IG 4. Generalized peritoneal inflammatory response associated with injury. Note the rise and timeourse for fibrin and mesothelial cells. (Reprinted with kind permission of Springer Science�Businessedia from DiZerega GS, ed. Peritoneal Surgery. New York: Springer-Verlag, 2000.)

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IG 5. Biochemical events associated with peritoneal injury and possible adhesion formation. tPA,issue plasminogen activator; PAI, plasminogen activator inhibitor; uPA, urokinase plasminogen
ctivator. (Reprinted with permission from Attard and MacLean.13)

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This fibrin-rich exudate is a tacky substance and causes adjacent organs ornjured serosal surfaces to coalesce.21 Under normal circumstances, theormation of a fibrin matrix during wound healing is only temporary, andegradation of these filmy fibrinous adhesions by locally released proteasesf the fibrinolytic system occurs within 72 hours of injury.22 Fibrinolysisllows mesothelial cells to proliferate and the peritoneal defect to be restoredithin 4-5 days, preventing the permanent attachment of adjacent sur-

aces.13,22 If fibrinolysis does not occur within 5-7 days of peritoneal injury,r if local fibrinolytic activity is reduced, the fibrin matrix persists.17 If thisccurs, the temporary fibrin matrix gradually becomes more organized asollagen-secreting fibroblasts and other reparative cells infiltrate the ma-rix.14,17

ediators Involved in Adhesion FormationThe newly recruited inflammatory cells release a host of inflammatoryediators, including cytokines and chemoattractants that may exacerbate

he response at several points of adhesion formation (Fig 5).18 Severalytokines contribute to the suppression of fibrinolysis and adhesionormation. Transforming growth factor (TGF-B) has been identified asaving a role in adhesion development by promoting fibrosis and alsoesothelial cell proliferation rather than fibrinolysis.23 Interleukin-1 has

lso been linked to adhesion formation as an inhibitor of fibrinolysis viatimulation of PA-I.24 Substance P, a tachykinin peptide promotesdhesion formation by inhibiting fibrinolysis via decreasing the amount of-PA in the peritoneum.18 For a comprehensive summary of the media-ors, genes, and factors involved in adhesion formation, we recommendecent articles by Reed and colleagues18 and Attard and Maclean.13

trategies for Adhesion ReductionAdhesion reduction agents can be broadly separated into 2 categories.he first are the pharmacological therapies given around the time of theatient’s operation. The second encompasses topical products appliedirectly to the operative site.Attard and Maclean have identified 6 mechanisms by which adhesion

ormation can be disrupted (Table 4): (1) decreasing peritoneal damage, (2)ecreasing the early inflammatory response, (3) prevention of fibrin forma-ion, (4) increasing fibrinolysis, (5) preventing collagen deposition, and (6)roviding barriers to adhesion formation.13 In theory, each of these processesould be controlled by surgical technique, pharmacological therapy, and usef topical intra-abdominal products at the time of operation. Many different
harmacological agents have been tried to achieve adhesion reduction.25

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here is sound logic behind the use of such agents, although their effective-ess has been somewhat limited. Reports in the literature describe theffective use of a large number of pharmacological agents in experimentalnimal studies.25 However, few agents progress to clinical trials.Several compounds in the laboratory have been noted to decrease adhe-

ions by interfering with fibrin deposition: nonsteroidal anti-inflammatoryrugs (NSAIDs), heparin, and corticosteroids. NSAID action targets prosta-landin synthesis, decreasing the inflammatory response from the start.26

eparin acts directly on the coagulation cascade by inhibiting the internalathway of the coagulation cascade by acting on factor Xa and thrombin viantithrombin. Corticosteroids may also have potential to inhibit adhesionormation via immune modulation, but studies have not been able toemonstrate this convincingly.27 Drugs that alter the inflammatory responseollowing operation have been most studied. The drugs include steroids andhe NSAIDs. The balance between adhesion reduction and acceptableystemic side effects, such as bleeding and impaired wound healing has beenifficult to overcome for these agents. Therapeutic anticoagulation to preventbrin deposition or the use of streptokinase to promote fibrinolysis has notad a significant effect on adhesion reduction in animal studies, and againhere is the concern for the risk of postoperative bleeding. The results fromtudies using streptokinase and urokinase have been equivocal or evenarmful in some studies.13

For a thorough review of the status of pharmacological strategies fordhesion prevention, we recommend recent articles by Attard andaclean13; and Lauder and colleagues.,25 Obviously, a pharmacologic

gent that would reduce inflammation and optimize fibrinolysis postop-ratively without causing bleeding or impairing wound healing would ben ideal candidate for adhesion prevention.18

aparoscopic vs. Open Surgery and AdhesionsSurgeons who perform laparoscopic surgery appreciate and recognize

hat adhesion formation is less after laparoscopic procedures, such as

ABLE 4. Mechanisms by which adhesion formation can be disrupted

Decreasing peritoneal damageDecreasing the early inflammatory responsePrevention of fibrin formationIncreasing fibrinolysisPreventing collagen depositionProviding barriers to adhesion formation

holecystectomy and hernia repair, than after the same procedures performed


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s open operations. This is believed to be so because there is less damage tohe peritoneum—both parietal and visceral—and less handling of the tissueith laparoscopy. Gutt and colleagues, general surgeons, wrote about this

n 2004.28 They reviewed the published literature on this topic and found5 reports to evaluate from 1987 to 2001: 3 clinical and 12 experimental.n the 3 clinical studies, adhesions following laparoscopy were less thanfter open surgery in comparable groups of patients. Lundorff andolleagues evaluated adhesions at the operative site after open andaparoscopic operation for ectopic tubal pregnancy in 73 women.29 Theuthors found significantly fewer adhesions at the operative site in theaparoscopic group. Milingos and colleagues found similar results inatients who had surgical adhesiolysis for infertility.30 A third studyompared adhesion formation between the liver bed, the omentum, andhe duodenum after open or laparoscopic cholecystectomy.31 After openholecystectomy, all patients (100%) had thick extensive adhesions to theperative site vs. 44% of patients after laparoscopic cholecystectomy, andhese adhesions were loose and easy to separate. In this analysis of theata, the authors concluded that laparoscopic surgery is associated with aeduction in the formation of adhesions after abdominal operations in alllinical and most experimental studies.An update of the current role of the topical gels and the membranearriers for the surgeon to use in the operating room will not be givenere; it is the subject of the last section in this monograph.

hysiology of Small Bowel Obstruction

ntroductionIn this section, we will describe the pathophysiology of bowel obstruc-

ion by focusing on these key components: intraluminal gas, intestinaluid, the microflora, the blood flow, and intestinal motility.Small bowel obstruction affects the physiology of the normal intestine

nd has systemic effects due to changes in fluid and electrolyte balance,uid shifts from one space to another, and hemodynamic changesecondary to hypovolemia and dehydration. Simple mechanical obstruc-ion of the small intestine causes the accumulation of gas, fluid, andlectrolytes proximal to the point of obstruction and leads to distention ofhe intestine. Intestinal activity increases in an effort to overcome thebstruction, accounting for the colicky pain and the diarrhea that someatients experience even in the presence of complete bowel obstruction.32

he rate at which symptoms and complications develop depends on
uminal volume, bacterial proliferation, and alterations in motility and

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erfusion. If the intramural pressure becomes high enough, intestinalicrovascular perfusion is impaired, which leads to intestinal ischemia

nd, ultimately, necrosis. This condition is known as strangulated bowelbstruction.32

ntestinal GasNormally, most of the gas in the gut and that seen on plain abdominal

adiographs consists of swallowed air; the remainder can be attributed toarbon dioxide from the neutralization of bicarbonate in the duodenum,nd organic gases such as methane and hydrogen sulfide from bacterialetabolism. The intestine rapidly absorbs carbon dioxide, which is then

eleased from the body through the lungs. Nitrogen and the organic gasesre not absorbed by the intestine and comprise most of the gas normallyxpelled from the rectum as flatus.33 With mechanical intestinal obstruc-ion, gaseous distention of the intestine occurs because the gas has nooute of escape. Because obstructed patients usually continue to swallowir in varying quantity, they experience progressive accumulation ofntestinal gas consisting mostly of nitrogen.33-35 This is one reason forlacing an NG tube.A particularly serious form of bowel obstruction is the closed loopbstruction in which a segment of bowel is obstructed proximally andistally as with a twist or volvulus of the bowel around or by an adhesionhat traverses and compresses the bowel in 2 places. In such cases, theccumulating gas and fluid cannot escape either upstream or downstreamrom the blocked segment, and luminal pressure will quickly increase andead to decreased bowel wall perfusion and bowel ischemia.

ntestinal FluidIn addition to ingested food and drink, up to 5 to 10 L of salivary,astric, pancreatic, biliary, and intestinal secretions enter the digestiveract each day. Normally, most of the fluid is reabsorbed by the smallntestine, as only approximately 1 L of fluid enters the colon from theleum daily.33

In mechanical obstruction, the intestine proximal to the site of obstruc-ion fills with fluid and gas. This fluid is not absorbed as in the normalntestine, and the distended bowel over time begins to secrete fluid ratherhan absorb fluid and contributes to a state of intravascular dehydration orypovolemia. Loss of fluid and electrolytes from the intravascular spaceccurs by several routes as the intestine distends; this is a critical event inowel obstruction for several reasons.
First, intestinal distention may stimulate reflex vomiting leading to the

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oss of fluid and electrolytes. Second, distention increases intestinalecretion with movement of fluid from the intravascular compartment tohe intestinal lumen. In humans, distention causes increased secretion ofater and electrolytes into the lumen by an incompletely understoodechanism.36 In the presence of obstruction, the small bowel reverses its

ormal function of absorption, and begins to secrete fluid into the lumenf the obstructed bowel. This phenomenon compounds the problem ofistention and fluid movement into the lumen. In addition, fluids like bile,astric juice, and oral liquid intake accumulate in the bowel proximal tohe obstruction and cause further intestinal distention, resulting in aelf-perpetuating cycle. Dehydration can result from the progressive lossf fluid and electrolytes into the intestinal lumen.37 A third route of fluidnd electrolyte loss is from intestinal edema, which gives the intestinalall the congested, swollen appearance often found at operation. A fourth

oute for loss of fluid from the intravascular space is by transudation ofuid through the serosal surface into the peritoneal cavity to produce free

ntraperitoneal fluid.33

Experimental studies and clinical investigation have demonstratedhat elevation of luminal pressures above 20 cm H2O inhibitsbsorption and stimulates secretion of salt and water into the lumenroximal to an obstruction.36-38 In closed-loop obstruction, luminalressures can exceed 50 cm H2O and may account for a substantialroportion of luminal fluid accumulation.39 In simple open-loopbstruction, distention of the lumen by gas and fluid rarely leads touminal pressures higher than 8-12 cm (H2O).40 Thus, in open-loopbstruction, the contributions of high luminal pressures to fluidypersecretion may not be as important.41

Accumulation of fluid in this third space accounts for the dehydra-ion and hypovolemia observed in cases of SBO.42 Dehydration canevelop within hours, depending on the degree and location ofbstruction and the amount of vomiting. The metabolic effects of fluidoss depend on the site and duration of the obstruction. With aroximal obstruction, dehydration may be accompanied by hypochlo-emia, hypokalemia, and metabolic alkalosis associated with increasedomiting. Distal obstruction of the small bowel may result in largeuantities of intestinal fluid into the bowel. Oliguria and hemocon-entration can accompany the dehydration as well as hypotension andhock. In severe cases of bowel obstruction, increased intra-abdominalressure, decreased venous return, and elevation of the diaphragmompromising ventilation may occur. These factors can serve to
urther potentiate the effects of hypovolemia.42

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ntestinal Blood FlowIntestinal blood flow is influenced by luminal pressure, mesenteric flow,

nd systemic blood pressure. As the intraluminal pressure increases in theowel, a decrease in mucosal blood flow can occur. With ongoing gas anduid accumulation, the bowel distends and intraluminal and intramuralressures increase. These alterations are particularly noted in patientsith a closed-loop obstruction in which greater intraluminal pressures are

ttained. A closed-loop obstruction, produced commonly by a twist of theowel, can progress to arterial occlusion and ischemia if left untreated anday potentially lead to bowel perforation and peritonitis.42 If the

ntramural pressure becomes high enough, intestinal vascular perfusion ismpaired, which leads to intestinal ischemia and ultimately necrosis of theall and perforation. This condition is called strangulated bowel obstruc-

ion32 (Fig 6).

lterations of Intestinal MotilityAbdominal colic is a hallmark of SBO and is related to gut motility.mall intestinal obstruction alters the normal motility of the gastrointes-

inal tract. Fluid and gas accumulate above the point of obstruction,ausing proximal distention. The bowel responds to distention witheriodic bursts of neuromuscular activity resulting in peristaltic rushes.hese paroxysmal, wavelike movements begin in the proximal bowel and

IG 6. Early bowel strangulation associated with small bowel obstruction (SBO). Note the darkenedoop of bowel to the left. (Color version of figure is available online.)

raverse the entire length of intestine above the point of obstruction.


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eriods of activity are followed by quiescent periods of variable duration.he intestine distal to the obstruction, however, maintains a reduced levelf peristaltic activity.33 Later in the course of obstruction, the intestinesecome fatigued and dilate, and the contractions become less frequent andess intense.42

hanges in the MicrofloraThe normal small intestine contains a low concentration of bacteria,

anging from 102 to 104 viable organisms per milliliter in the proximalejunum to 103 to 107 viable organisms per milliliter in the distalleum. The composition of the bacterial flora in the proximal jejunumhanges from fungi and predominately gram-positive facultativeacteria, such as streptococci, staphylococci, and lactobacilli, toredominately aerobic coliforms and anaerobic species in the distalleum and colon.33,43

Small bowel obstruction produces stasis of intestinal contents. Aremendous overgrowth of aerobic coliforms and anaerobic speciesroximal to the site of obstruction alters the normal proximal-to-distalradient change in bacterial flora. Bacterial concentrations increase tos high as 1010 to 1012 viable organisms per mL of intestinalontent.33,44 Studies have shown an increase in the number ofndigenous bacteria translocating to mesenteric lymph nodes and evenystemic organs. However, the importance of this bacterial transloca-ion on the clinical course is not clear.42 If the intestinal wall losesiability, altered intestinal permeability can allow bacteria and bacte-ial products to enter the circulation or peritoneal cavity, causingoxemia, septicemia, or both.33

linical PresentationThe clinical presentation of patients with SBO may vary widely from

ubtle nonspecific pain to florid peritoneal signs related to strangula-ion and bowel perforation. However, classic symptoms of bowelbstruction include nausea and vomiting, a distended abdomen,olicky abdominal pain, and alteration in flatus and stool passage. Theymptoms vary widely with the degree of bowel obstruction from aow-grade partial SBO associated with a scaphoid abdomen andrampy pain with eating to a complete bowel obstruction characterizedy massive abdominal distension, constant abdominal pain, andbstipation for longer than 24 hours. The clinical features of SBO arefunction of the level of obstruction, degree of lumen obstruction,

uration of the obstruction, and the amount of distension. Physical


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xamination classically reveals abdominal distension, high-pitchedowel sounds, and diffuse tenderness to palpation, all of whichuggest a diagnosis of bowel obstruction.

ifferential DiagnosisObstruction vs. Ileus. Making the distinction between an SBO and an

leus depends primarily on the patient history, the clinical setting, the physicalxamination, the findings on the radiological studies, and a consideration ofhe likely causes. Surgeons are usually able to correctly distinguish patientsith SBO from those patients with an ileus. In the past, even for experienced

urgeons, these two diagnoses were often difficult to separate and identifyecause standard abdominal radiographs did not provide the information were provided on computed tomography (CT) scans today and because clinicalndings and symptoms overlap: abdominal distention, nausea, vomiting, andbdominal pain are common to both.Ileus is a condition of abnormal and inhibited motility of the gastrointes-

inal tract. Gastric content, liquids, and intestinal fluids fail to move throughhe intestinal tract because of ineffective intestinal peristalsis. There is noechanical obstruction, but effective organized aboral passage of liquids and

as is absent. Other adjectives that describe ileus are paralytic, adynamic, andostoperative. It is commonly observed in a patient who has just hadbdominal surgery and the bowels have not resumed normal function. Ileuss also frequently seen in intensive care unit (ICU) patients who are criticallyll and are receiving a variety of medications, many of which affect gutotility. In hospitalized patients, ileus is generally gradual to acute in onset

nd resolves once the underlying condition has been corrected. Patients withSBO, on the other hand, have normal intestinal motility but, instead, haveblockage of the gut that prevents normal passage of fluid and gas through

he intestine. There is a physical barrier that obstructs the intestinal lumen atome point along its path; it could be an adhesion, an abdominal hernia, or aumor. Abdominal distention with crampy, colicky, abdominal pain, nauseand vomiting, and obstipation are the hallmark symptoms. Early on, bowelounds are active and high pitched.The typical patient with an SBO will come to the office or emergencyepartment complaining of crampy abdominal pain, nausea or vomiting,nd worsening obstipation. The patient will have hyperactive bowelounds, tympany to percussion, and likely a history of previous abdom-nal surgery. The most common causes are adhesions and abdominal wallernias. Plain radiographs of the abdomen will show gaseous distention ofhe small bowel in the supine position and often show an outline of the
alvulae conniventes. The upright radiographs classically will show

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ir-fluid levels in inverted U-shaped loops of small intestine (Fig 7).33

enerally, there is little gas in the colon. Unlike a CT scan, these simpleadiographs do not show points of obstruction in the bowel or transitionoints from dilated bowel to normal caliber gut.The patient with an ileus, on the other hand, is more likely to be in theospital receiving treatment for a medical condition or recovering from aajor operation when the postoperative ileus exceeds the expected

eriod. Plain radiographs of the abdomen show gas in both the small andarge bowel (Fig 8). There are many conditions that can inhibit intestinalotility and cause an ileus picture. The common conditions are a recent

bdominal operation; acute events in the abdomen such as appendicitis,ancreatitis, and ureteral colic; multiple trauma with rib fractures orelvic fractures; retroperitoneal hematoma; pneumonia or sepsis; or renalailure, heart failure, multisystem organ failure (MSOF), and just about

IG 7. Multiple air/fluid levels in inverted U-shaped loops with associated small bowel distention indhesive SBO. Arrow points to one of many air/fluid filled levels in this abdominal xray. (Reprintedith permission from WetPaint, http://wikiradiography.com/page/Small�Bowel�Obstruction.)

ny critical illness that places a patient in the ICU. Metabolic derange-


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ents, sepsis, organ failure, and drug and medication toxicity each canontribute to an ileus. Many drugs affect the sympathetic and parasym-athetic innervation of the gut and thus motility. The opiates, calciumhannel blockers, psychotropic drugs, and pain medicines are commonontributors to ileus. It is important to remember that in the surgicalatient, unrecognized or untreated infection either in the abdomen or thehest is often a cause of prolonged ileus.45

Distinguishing mechanical SBO from ileus is best assisted by radio-raphic examinations. First, the plain films will demonstrate whether anbstruction is present. The CT scans of the abdomen and pelvis with oralontrast show where the obstruction is and what the lesion is. When ileuss present, there is no focal point of obstruction; gas and liquid are seen

IG 8. Distended small and large bowel with air throughout the entire GI tract, including rectum.rrow points to air in the rectum of this patient with paralytic ileus. (Reprinted with permission frometPaint, http://wikiradiography.com/page/Small�Bowel�Obstruction.)

hroughout the small bowel and colon. There is no transition zone as one



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ees with SBO with dilated bowel upstream and decompressed bowelistally. An added benefit of the CT scan is that it images the entirebdomen and its contents and can identify other causes for the ileus andbdominal distention, such as an abscess, diverticulitis, or pancreatitis,hich is really the patient’s problem.Fortunately, today we have very good imaging techniques to help us

valuate the bowel and its neighboring organs. When the gut is not working,e have total parenteral nutrition (TPN) and good critical care units to

upport the patient until the underlying conditions can be treated.Small Bowel vs. Large Bowel Obstruction. With the assistance ofigh-quality body imaging techniques, it is usually possible for theurgeon to distinguish SBO from a large bowel obstruction (LBO). Yet,here is some overlap in the signs and symptoms that can make thisistinction a challenge when one first sees the patient in the office or themergency department.The symptoms of SBO are abdominal distention, crampy abdominal pain,ausea, vomiting, and constipation. Vomiting, bilious or feculent, is com-on, whereas this is a later event in colonic obstruction. Paroxysms of

bdominal pain occurring at 4-10-minute intervals are typical.Large bowel obstructions, usually from colon cancer or strictures fromiverticulitis, are seldom acute; there is usually a several-day to several-weekistory of constipation and change in bowel habits. Mid abdominal pain andbdominal distention are the 2 most consistent signs. Blood in the stool andnemia are strongly suggestive of carcinoma. Per rectal examination, anmpty rectal vault is suggestive of a proximal colon obstruction, and blood onhe examining finger indicates a distal lesion. Diarrhea may be present as aunction of liquid stool passing around the obstructing lesion. The abdomens distended and tympanic as with the SBO. Cascading bowel sounds andorborygmus are often present, whereas high-pitched bowel sounds are heardnly if there is superimposed SBO. Patients with LBO are likely to be morelderly than the SBO group of patients.The progression of symptoms in colonic obstruction depends in part on theatency of the ileocecal valve. If this valve is incompetent, there is retrogradeecompression of the colon, the onset of symptoms will be gradual, and thereay be some feculent vomiting. Radiologic studies are the most important

iagnostic tools to establish the presence or absence of colonic obstructionnd the location. Plain abdominal radiographs should be obtained first in thepright (if possible) and supine positions. These will show mild to markedistention of the colon proximal to the lesion and may show small bowelistention if the ileocecal valve is incompetent (Fig 9). The plain radiographs
an be diagnostic for cecal volvulus and sigmoid volvulus (Figs 10, 11A and

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). A CT scan of the abdomen provides valuable information and is part ofhe evaluation unless the patient has an acute abdomen and needs resuscita-ion or an exploratory laparotomy first.The CT scan will demonstrate not only the LBO but also the location

nd nature of the lesion plus information about bowel viability, the risk oferforation, bowel diameter, and involvement of other organs.In summary, abdominal distention, pain, and anorexia are common tooth SBO and LBO. However, the patients with colonic obstruction areikely to be older (�60 years) than the SBO patients; and colon tumorsnd strictures are common causes of colon obstruction, whereas SBO issually caused by adhesions and abdominal wall hernias.

valuation of SBO in the Gastric Bypass PatientThe incidence of SBO following laparoscopic gastric bypass is approx-

IG 9. Distended large bowel with competent ileocecal valve in a patient with obstructing rectalarcinoma. (Reprinted with permission from Jon Lund, http://learncolorectalsurgery.com/#/abdominal--ray/4549818580.)

mately 3.5%, and one half of these are caused by internal hernia, which


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s now generally recognized as a particularly dangerous cause ofbdominal pain in patients after gastric bypass. Clinically, these patientsay present with symptoms of bowel obstruction, and early CT scan is

ecommended because of the risk of bowel strangulation. Several CTndings have been found to be predictive of internal hernia, particularly

he “mesenteric swirl” (Fig 12). Other signs of internal hernia includeushroom hernia shape, SBO, clustered small bowel, tubular distalesenteric fat surrounded by bowel loops, small bowel behind superioresenteric artery, and right-sided location of jejunojejunostomy.

iagnosisLaboratory Studies in SBO. Patients presenting with SBO usually haveolume deficits caused by vomiting and “third spacing” into the lumennd wall of the obstructed bowel, and into the peritoneal cavity. Emergent

IG 10. Massively dilated colon in a patient with cecal volvulus. (Reprinted with permission frometPaint, http://www.wikiradiography.com/page/Large�Bowel�Obstruction.)

peration without resuscitation may result in cardiovascular collapse and


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eath with the induction of general anesthesia. Commonly, the deficit ofsotonic fluid is several liters, and the associated hemoconcentration mayesult in a spuriously elevated hematocrit and hemoglobin level. If there isvidence of recent GI blood loss, this must also be considered whennterpreting the hematocrit in the patient with SBO. Although the white bloodell (WBC) count may also be elevated somewhat by severe dehydration,eukocytosis greater than 20,000/mL should prompt concern for bowelompromise or perforation in the patient with SBO. In patients with SBOho are being managed nonoperatively, the WBC should be monitored;

lthough a normal WBC is reassuring and an elevated WBC is concerning,t must be remembered that when predicting bowel compromise, theiagnostic accuracy of this test alone is poor. Operation in SBO should nevere delayed or initiated on the basis of WBC alone. However, in patients withBO being managed nonoperatively, WBC is an important part of the clinicalicture. In general, compromised bowel in the setting of SBO is very unlikelyf the patient has a WBC less than 16,000/mL, and no fever, and no pain orenderness, and no tachycardia, and no ominous radiologic findings.Electrolyte disorders are common in patients with SBO because of

IG 11. Sigmoid volvulus demonstrating a 14-cm sigmoid colon before (A) and after (B) rectal tubeecompression. (Reprinted with permission from http://www.learningradiology.com/archives04/OW%20087-Sigmoid%20volvulus/sigmoidvolvcorrect.htm. Copyright LearningRadiology.com. All

ights reserved.)

omiting and lack of oral intake. The most common acid/base abnormalities


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re metabolic (contraction) alkalosis (related to maximal renal sodiumeabsorption in exchange for H�) and metabolic acidosis (related to GIicarbonate loss and hypovolemic tissue hypoperfusion). The latter is oftenssociated with a subtle but perceptible increase in minute ventilation becausef respiratory compensation for the metabolic acidosis. The most commonlectrolyte abnormality is hypokalemia. Fluid and electrolyte replacement isith isotonic solution (normal saline preferably) with additional potassiumrovided there is evidence of adequate renal function. The blood ureaitrogen and creatinine are commonly elevated because of renal hypoperfu-ion, as is the blood urea nitrogen/creatinine ratio.Serum lactate levels are often routinely followed in patients with SBO,

lthough their clinical usefulness is questionable. On admission, the lactateevel may be elevated because of volume-related global hypoperfusion.lthough in the resuscitated patient with SBO a sudden spike in a normalized

erum lactate may indicate the onset of small bowel compromise, this is notecessarily the case. The segmental bowel infarction or perforation related toowel obstruction can certainly occur in the setting of a normal serum lactate.n fact, most patients requiring bowel resection for ischemia in the setting ofBO probably have normal serum lactate levels.Serum amylase levels are useful only to the extent that they rule outancreatitis as a cause of the presenting abdominal pain in patients with SBO;

IG 12. Dilated small bowel and “mesenteric swirl” associated with internal hernia after gastricypass (Peterson’s hernia). Arrow points to pinwheel-like swirl.

hey are not useful in predicting small bowel viability or perforation.


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Imaging Studies in SBO. Traditionally, an abdominal series or obstruc-ion series was the most common and useful radiologic test in the patient withBO, but it has now been supplanted in many settings by the CT scan. Thiset of plain radiographs consisted of an upright chest and upright abdominaladiograph, and a supine abdominal radiograph. If upright radiographs are notossible, a decubitus cross table lateral radiograph of the abdomen may beubstituted to look for free air. Patients with an SBO may have a radiographicattern ranging from massively distended small bowel with no air in theolon or rectum (Fig 13), to a radiograph that reveals multiple air-fluid levelsith less abdominal distension and some air in the colon and rectum (Fig 14).he radiologist reading the former case will usually assign a diagnosis ofomplete bowel obstruction. The latter circumstance would be labeled a

IG 13. Massive dilation of small bowel with no air in the colon or rectum. Patient had a completeowel obstruction that necessitated laparotomy. (Reprinted with permission from Cameron JL. Currenturgical Therapy (ed 8). Philadelphia, PA: Mosby, 2004.)

artial SBO. Studies demonstrate that in those patients diagnosed as having


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“complete” bowel obstruction by the radiologist, more than 80% willequire an operation compared with 10% to 15% of those labeled as having“partial” bowel obstruction. Occasionally, the abdominal series with 1 or 2

ir-fluid levels will reveal a single loop of bowel that is somewhat distended.If the SBO is quite proximal, the stomach, duodenum, and short

egment of jejunum proximal to the obstruction may be adequatelyecompressed by repeated vomiting or NG suction, and the plainbdominal radiographs may be interpreted as normal or nonspecific (Fig5). Pneumatosis in the bowel wall and/or portal venous gas may be seen onlain radiograph, and in the setting of abdominal pain and small bowelistention, this is an ominous sign that warrants urgent operation (Figs 16 and7). In patients with obturation of the small bowel, usually the terminal

IG 14. Partial SBO associated with air-fluid levels, abdominal distention, and air in the colon andectum. Arrows point to colorectal air. (Reprinted with permission from Cameron JL. Current Surgicalherapy (ed 8). Philadelphia, PA: Mosby, 2004.)

leum, with a gallstone, findings on plain radiographs may be pathogno-


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onic: distal SBO and pneumobilia. Occasionally, the obstructing gall-tone is visualized if it contains adequate calcium to render it sufficientlyadio-opaque. Finally, when there is a preponderance of luminal fluid andpaucity of luminal air, the diagnosis of SBO may be missed by plain

adiographic studies.If the SBO is deemed to be partial on clinical grounds and the patient

s stable, nonoperative management is appropriate. However, unless it cane reliably verified by the patient and caregivers that the patient is notompletely obstipated, the onus is on the surgeon to document radiolog-cally that the SBO is incomplete if nonoperative management isontinued for more than 24 hours. This may be accomplished by the oraldministration of a small amount (100 mL) of barium or gastrograffin,ollowed by serial plain abdominal radiographs. If the contrast reaches the

IG 15. Arrow points to a single dilated segment of small bowel in a high jejunal obstruction. Notehe paucity of dilated loops and distention. (Reprinted with permission from WetPaint, http://ikiradiography.com/page/Small�Bowel�Obstruction.)

ecum in �24 hours, the obstruction is partial and it is very likely




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IG 16. Pneumatosis in the bowel wall (arrows) associated with necrotic bowel secondary to anBO. (Reprinted with permission from Kernagis LY, Levine MS, Jacobs JE, et al. Pneumatosisntestinalis in patients with ischemia: correlation of CT findings with viability of the bowel. Am J
oentgenol 2003;180:733-6.)
IG 17. Venous air (arrows) associated with pneumatosis.


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�95%) that there will be clinical resolution without the need forperation; otherwise the SBO must be considered complete and operationhould be planned if there are no clinical signs of resolution (Fig 18).It has been suggested that the oral administration of a small quantity (eg,00 mL) of gastrograffin can lead to the resolution of SBO. Gastrograffins a hyperosmolar liquid that draws water into the bowel lumen, perhapsmproving bowel edema and enhancing contractility. It should be usedautiously in patients at risk for pulmonary aspiration, as introduction of

IG 18. Gastrograffin small bowel follow-through in a patient with “partial” SBO that failed to resolve.ailure of the contrast to reach the colon is an indication for surgery. (Reprinted with permission frommall Bowel Obstruction. The original article was published at www.surgwiki.com) (Blackwellublishing Asia Pty Ltd and such article can be found at the following URL: http://www.surgwiki.com/iki/Small_bowel_obstruction.)

he material into the bronchial tree can cause life-threatening pneumoni-


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is. Two recent meta-analyses have examined the benefit of gastrograffinn patients with SBO. Branco and colleagues evaluated 14 prospectivetudies and found that the appearance of oral contrast in the colon within4 hours of administration was 96% sensitive and 98% specific indentifying those patients with SBO who would have clinical resolution ofBO without the need for operation.46 These authors also found that theral administration of water-soluble contrast reduced the need forperation by approximately 35% (P � 0.05) and shortened hospital stayy almost 2 days (P � 0.05). In another meta-analysis, Abbas andolleagues found a similar beneficial effect of gastrograffin on hospitaltay in patients with SBO (�1.83 days, P � 0.05), but not on the need forperation (OR � 0.81, P � 0.3).47 Neither study discussed any adverseffects of gastrograffin. It can be concluded that the oral administration ofastrograffin should be considered in patients with SBO who do notbviously require urgent operation on the basis of clinical and radiologicndings.Small bowel follow-through using barium is often very helpful in the

valuation of potential SBO due to Crohn’s disease. In this patient withnown Crohn’s disease, small bowel follow-through identified a veryight stricture in the terminal ileum (Fig 19). The study provides a usefuload map for surgery.Ultrasound is a noninvasive study that may yield useful information

egarding the patient with SBO. Dilated fluid-filled loops with or

IG 19. Barium small bowel follow-through revealing a tight stricture (arrow) in the terminal ileum inpatient with partial SBO and known Crohn’s disease.

ithout peristalsis are readily apparent on ultrasound. Gallstones and


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ir in the gallbladder suggest gallstone ileus. The absence of abdom-nal fluid can be reassuring in the stable patient being managedonoperatively, as new ascites can be an ominous sign in patients withowel obstruction.Double contrast CT scan has become the imaging procedure of choice

or most patients with the clinical diagnosis of SBO. Mallo and colleagueseviewed 15 studies evaluating the diagnostic usefulness of CT scan indentifying patients with SBO who had bowel ischemia or completebstruction.48 Eleven of the studies reviewed evaluated the CT diagnosisf ischemia in SBO. The aggregated statistics from these 11 studies weres follows: positive predictive value (PPV) 79% (167 of 212; range, 69%o 100%), negative predictive value (NPV) of 93% (496 of 531; range,3.3% to 100%), sensitivity of 83% (167 of 202; range, 63% to 100%),nd specificity of 92% (496 of 541; range 61% to 100%). Seven of thetudies reviewed by Mallo and colleagues evaluated CT in the diagnosisf complete or high-grade obstruction (vs. partial obstruction) in patientsith SBO. The aggregated PPV of CT for complete obstruction was 92%

168 of 182; range, 84% to 100%), NPV was 93% (211 of 226; range,6% to 100%), sensitivity was 92% (168 of 183; range, 81% to 100%),nd specificity was 94% (211 of 225; range, 68% to 100%). This studynderscores the diagnostic usefulness of abdominal CT scan in patientsith the clinical diagnosis of SBO.Typically, the initial CT scan in the patient with SBO shows proximalilated small bowel with luminal contrast, and distal collapsed smallowel and colon void of luminal contrast (Fig 20). If there is no oralontrast in the bowel distal to the transition point and if nonoperativeanagement is planned, follow-up scan or plain radiograph is done in 12

o 24 hours to document movement of the contrast into the lumen of theistal small bowel and colon. If this is not demonstrated, the SBO shoulde considered complete and operation planned. The presence of aransition point per se predicts neither the need for operation nor theailure of nonoperative treatment in SBO.49 CT scan can be helpful indentifying the etiology of the SBO, such as internal hernia (Fig 21),bdominal wall hernia (Fig 22), intussusception (Fig 23), tumor or mass,rohn’s disease (Fig 24) metastatic cancer, primary tumor, or ischemiand signs of bowel compromise such as pneumatosis intestinalis orneumoperitoneum (Fig 25). Schwenter and colleagues showed onultivariate analysis that the following factors predicted the need for

owel resection in patients with bowel obstruction: the presence of morehan 500 mL of ascites on CT (P � 0.002); reduction of CT bowel wall
nhancement (P � 0.011); abdominal pain for �4 days (P � 0.007);

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IG 20. CT scan demonstrating SBO with a clear transition zone (arrow) followed by collapsedowel. (Reprinted with permission from Cameron JL. Current Surgical Therapy (ed 8). Philadelphia,
A: Mosby, 2004.)
IG 21. Internal hernia after gastric bypass with dilated loops of small bowel and classic mesenteric
wirl (arrow).

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IG 22. CT scan demonstrating incarcerated right inguinal hernia (arrow) in a patient with SBO.Reprinted with permission from Furukawa A, Yamasaki M, Furuichi K, et al. Helical CT in theiagnosis of small bowel obstruction. Radiographics 2001;21:341-55, © The Radiological Society of
orth America.)
IG 23. Typical “bulls eye” (arrow) or “target sign” associated with small bowel intussusceptionausing SBO. (Reprinted with permission from James Heilman, MD, http://commons.wikimedia.org/
iki/File:VolvulusCT.PNG.)

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bdominal tenderness with guarding (P � 0.009); WBC � 10,000/mL (P �.085); and C-reactive protein � 75 mg/L (P � 0.007).50 All patientsith 4 or more of these variables required resection, whereas only 1atient who had no positive variables required resection. Fever andransition point on CT scan were not independent predictors of compro-ised bowel in this study. Zielinski did a similar type of analysis and

ound on multivariate analysis that the independent predictors of the needor operation in SBO were vomiting (OR � 4.67; P � 0.007); ascites onT (OR � 3.80; P � 0.006); mesenteric edema on CT (OR � 3.59; P �.011); and the lack of the small bowel feces sign (OR � 0.19; P � 0.011).51

gain, fever and transition point on CT were not independent predictors ofperation; neither were leukocytosis and serum lactate level. In a subsequentrospective validation, Zielinski and colleagues distilled the predictive modelown to 3 independent variables: obstipation, mesenteric edema on CT scan,nd lack of small bowel feces sign on CT scan.52

The “whirl sign” is a “swirl of mesenteric soft tissue and fat attenuationith adjacent loops of bowel surrounding rotated intestinal vessels” (Fig2). In a retrospective study, Duda and colleagues reviewed 194 CT scanshowing SBO and found that 40 scans contained the “whirl sign.” Eightyercent of patients with the “whirl sign” required operation (PPV �0%), but only 14% of patients without the sign required operationNPV � 86%).53 The “small bowel feces sign” is the presence of

IG 24. Patient with a history of subtotal colectomy for Crohn’s disease and an ileocolostomyresented with a high-grade partial SBO. CT scan reveals recurrent Crohn’s disease with a tighttricture at the previous anastomosis (arrow).

articulate material in dilated small bowel. This sign is present on CT


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can in approximately 50% of patients with SBO and may be moreommon in patients with more high-grade obstruction. However, by itselft is not a particularly useful finding in patients with SBO.

anagementBefore any diagnostic maneuvers are initiated, the patient with an SBO

hould undergo immediate resuscitation with intravenous isotonic volumeeplacement. Most patients with a prolonged course of nausea andomiting will develop a hypochloremic hypokalemic metabolic alkalosis.ccordingly, the replacement fluid of choice is normal saline withotassium supplementation. Fluids should be administered rapidly, with aoley catheter placed to monitor urine output as an index of euvolemia.he use of narcotic pain medications is somewhat controversial, butatients in whom a decision to operate has already been made should beiven adequate pain medication to give them some relief. In patients inhom the diagnosis is uncertain, the use of opiate medications is less

lear. Many surgeons prefer that the patient not be receiving narcoticshile they monitor the patient’s pain symptoms on physical examination.While the fluid and electrolyte resuscitation is being conducted,lacement of a standard length NG tube is indicated to decompress the

IG 25. Bowel strangulation with necrotic bowel seen on CT scan. Arrows point to nonviable segment ofowel. (Reprinted with permission from Cameron JL. Current Surgical Therapy (ed 8). Philadelphia, PA:osby, 2004.)

tomach and prevent accumulation of any other gas behind the point of


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bstruction. This virtually always brings relief to the patient and alsorotects against aspiration. Although long tubes with mercury-filled bagst the end were used in past surgical periods, virtually nobody uses longubes today because of the complexity of their management and littlevidence that their efficacy is any greater than standard length NGubes.54 In fact, multiple prospective studies show no advantage to usinghe longer tubes.The use of antibiotics in patients with SBO is also somewhat contro-ersial. Although no one argues with the need for preoperative antibioticsn the patient with bowel obstruction who is going to surgery, thereppears to be little evidence that antibiotic use in the patient with SBO isndicated, and few practitioners administer antibiotics while patients areeing observed.The clinical spectrum of SBO varies widely, but the 9 most common

linical scenarios include (l) complete bowel obstruction, (2) partialBO—high grade, (3) partial SBO—low grade, (4) bowel obstruction invirgin abdomen, (5) recurrent SBO, (6) bowel obstruction immediately

fter operation, (7) bowel obstruction in a patient with known malignancyr recurrent malignancy, (8) bowel obstruction with a known history ofrohn’s disease and (9) SBO after gastric bypass (Table 5). A briefonsideration of each of these clinical scenarios is helpful in deciding theest management course. The actual decision-making process for patientsith SBO is often the most difficult and challenging of any area inastrointestinal surgery. The clinician must be very alert and aware as her she manages the patient after admission to look for any signs ofmprovement or deterioration. Multiple follow-up abdominal radiographsust be obtained associated with frequent clinical reexaminations toonitor the progress of the patient.Patients with complete bowel obstruction merit the closest and most

ritical attention. Because of the dangers of incarceration leading to

ABLE 5. Clinical spectrum of small bowel obstruction (SBO)

Complete SBOPartial SBO—high gradePartial SBO—low gradeBowel obstruction in virgin abdomenRecurrent SBOSBO immediately after surgerySBO in patient with known malignancySBO in patient with Crohn’s diseaseSBO in patient s/p gastric bypass

trangulation as well as closed loop obstructions, patients with complete


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owel obstruction demand immediate attention. If a patient presents withignificantly distended bowel, a history of obstipation for the past 12ours, and no recent improvement, consideration should be given to goingo the operating room immediately. This is particularly true if the patientas unrelenting pain and the classic tetrad associated with strangulatedowel, including leukocytosis, fever, tachycardia, and severe abdominalain. The dictum that “the sun should never set on a complete bowelbstruction” is as true today as it was 50 years ago.Patients presenting with significantly distended bowel and crampy abdom-

nal pain, but who have evidence of gas in the colon and rectum on thebdominal radiographs as well as a recent history of having passed flatushigh-grade partial SBO), may be admitted for initial observation. Theseatients also require very close vigilance. They should be reexamined on aegular basis, and repeat abdominal radiographs should be obtained every 8o 12 hours to see whether the distended bowel is worsening or improving.atients with partial high-grade SBO should begin to improve within 24 to 48ours. It is clear that most cases of adhesive SBO that are likely to resolveill do so within 48 hours. Patients with high-grade obstruction who do not

mprove within 24 hours of admission should be taken to the operating roomor exploration. Few other diagnostic studies are indicated, although occa-ionally a CT scan will confirm the point of obstruction and edema of theowel proximal to the obstruction.The category of patients who have a low-grade partial SBO characteristi-

ally have less abdominal distension and have passed some gas or stoolecently but continue to have crampy abdominal pain and appear to partiallyesolve but become symptomatic on liquid or oral intake. With lessistension, less abdominal pain, and radiographs that reveal some improve-ent in the bowel gas patterns, these patients can be safely watched up to 5-7

ays as long as improvement is seen. This group of patients often benefitrom an enteroclysis study to demonstrate the site of obstruction and degreef luminal narrowing. A contrast study that shows substantial dilationroximal to the obstruction site and slow passage of contrast through thebstructed site after 5 days indicates the patient should probably be taken tohe operating room for adhesiolysis. On the other hand, if the patientontinues to improve, distension diminishes, and radiographs reveal resolu-ion of air-fluid levels, the patient may be cautiously placed back on cleariquids and advanced to a low-fiber diet as tolerated.Patients with bowel obstruction and a virgin abdomen virtually alwayserit an exploratory laparotomy for either diagnostic purposes or surgical

reatment of the offending etiology. Most commonly, the cause is
ncarceration in an abdominal wall hernia (Fig 26), but other causes

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nclude a tumor, intussusception, and previously undiagnosed Crohn’sisease. A CT scan preoperatively is often obtained but there is no reasono delay operating on a patient with this history because surgical treatments virtually always indicated. Any hernia encountered in the course ofreating this disease should be repaired at the time of operation. The onlyxception to this might be in a patient who has strangulated bowel, inhom a permanent mesh would be required. In that case, an absorbableesh may be indicated until the patient heals, followed by an elective

ernia repair with permanent mesh at a later date. Patients with a primaryalignancy should undergo resection of the obstructing tumor with

ymphadenectomy as indicated. If intussusception is found on explora-ion, the area of intussusception almost always requires resection so theeading point of the intussusception can be surgically removed. Findingbstructing Crohn’s disease in a patient with a virgin abdomen virtuallylways mandates removing the involved area of small bowel. Theecision to create a stoma vs. a primary anastomosis is a function ofowel distension and general condition of the intestine.Patients who develop a bowel obstruction immediately after operation

equire a different operative plan. The obstruction resolves in most ofhese patients within 10 to 14 days after operation, and the risk oftrangulation seems to be quite small. The management plan of choicesually involves resting the gut, initiating NG suction, and starting

IG 26. Cross table lateral radiograph revealing incarcerated umbilical hernia (arrow) in a patientith a virgin abdomen. (Reprinted with permission from WetPaint, http://wikiradiography.com/age/Small�Bowel�Obstruction.)

ydration. Occasionally, short-term TPN may be required while the




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bstruction is resolving. Most of these patients will probably not requireeoperation. Those who do present a clinical scenario of no improvementor a prolonged period and often show some worsening of symptoms.The patient with recurrent SBO represents another unique clinical

cenario. These patients often present with a history of multiple laparot-mies, a number of which were for lysis of adhesions. Often, the mostecent operation is described as a very difficult laparotomy with multipleerosal injuries and enterotomies. All attempts should be made to avoidnother laparotomy in these patients. Particularly in those patients with aistory of resolution with conservative management, NG decompression,ydration, and gut rest are indicated. TPN may be required while thebstruction is resolving and one should be patient enough to wait 10 to 14ays in these patients. However, in those patients who remain obstructedith little progress or show some evidence of deterioration manifested by

ncreasing distension and failure to resolve the obstipation, operation mayave to be considered. Preparation for laparotomy in this patient popu-ation requires a good deal of thought. The surgeon should schedule nother major cases on a day in which 1 of these difficult patients is treatedurgically. The operation usually involves a generous midline incisionnd a plan to take adhesions down from the ligament of Treitz all the wayo the ileocecal valve. Although there is some literature regardinglication of the small bowel after this procedure, it does not appear to beery effective and there is little evidence that it prevents furtherbstructions. More successful in the author’s hand has been the Bakerube, which is a long intestinal tube with a balloon at the end of it (Fig 27).his can be brought through the abdominal wall and through a Stamm-

ype gastrotomy and with the balloon inflated can slowly be milked all theay to the ileocecal valve. This long tube has the effect of preventing the

mall bowel from kinking in any given location. This long tube should beeft in place for 2.5-3 weeks, although most patients can be given a liquidiet around the tube. At the end of 3 weeks, the balloon should be deflatednd the tube very slowly withdrawn during a 5- to 10-minute period. Evenatients who have undergone bowel resection and have an anastomosisan usually have use of this tube with no problems with perforation. Thether option in this patient population is placement of an absorbablearrier, which can be wrapped around the bowel from the ligament ofreitz to the ileocecal valve. This material is a combination of hyaluroniccid and carboxymethylcellulose (see later in the text). Although thevidence in support of its use is not clear, in these desperate patients, anyttempt to decrease adhesions seems warranted.
Patients with a known history of Crohn’s disease and obstruction

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epresent another challenging clinical scenario. These patients have aistory of 1 or 2 previous resections, and now they are having difficultyating solid foods and even occasionally vomit up liquid. Most of theime, they do not have complete bowel obstruction, and enteroclysis studyr CT scan will reveal the site of obstruction and whether a string sign isresent (Fig 28). If the area of obstruction is fairly new and the patient hasad symptoms only recently, an attempt at conservative management withut rest, TPN, and steroids is warranted to see if this area will open up andhe patient can be advanced on diet. However, if after a 7- to 10-dayeriod, the patient does not resolve, consideration should be given toeoperation and resecting the strictured area.The final area of concern is the patient who presents with bowelbstruction with known intra-abdominal malignancy or in whom recur-ent malignancy is a possibility. Although there tends to be a nihilisticttitude regarding these patients, studies reveal that 30% of patients whoresent with this history will have an adhesion that can be lysed withesolution of the problem, 30% have a malignancy obstructing the bowelhat can be resected, and 30% have carcinomatosis for which no operations possible. Patients with this critical scenario deserve a laparotomy,articularly if it is unknown whether they have carcinomatosis.To summarize, the principles that guide the clinical management ofatients with suspected SBO are shown in Table 6. Thus, the diagnostic

IG 27. Lengthy Baker intestinal tube for use in stenting the small bowel of a multiply recurrent SBOatient. Tube is passed through the entire small bowel inflating the balloon in the cecum to preventetrograde retraction. The tube can be removed 3 weeks postoperatively. (Color version of figure isvailable online.) (Courtesy of Teleflex Medical Incorporated, Research Triangle Park, NC.)

valuation and management of patients with SBO are largely focused on


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he issues of etiology, the degree of obstruction (partial or complete), andmall bowel viability (ischemia or perforation). Not surprisingly then,odern abdominal imaging techniques, particularly CT scanning, have

ecome important in addition to the diagnostic armamentarium in the caref patients with SBO.

perative Management and Technical ConsiderationsWhen operative therapy becomes mandatory in patients with SBO,

iming of the procedure is often important. For example, in early

IG 28. Long “string sign” (arrow) in terminal ileum of a patient with diagnosed Crohn’s disease. TheT scan demonstrates dramatic luminal narrowing caused by active inflammation.

ABLE 6. Principles of clinical management of small bowel obstruction (SBO)

. Bowel infarction and/or perforation rarely complicate partial SBO but not infrequentlycomplicate complete SBO.

. Complete SBO, except perhaps in the postoperative period, rarely resolves without anoperation; partial SBO frequently resolves without operation.

. It can be difficult on the basis of history, physical examination, bloodwork, and plainradiography:a. To correctly identify all patients with threatened small bowel in the setting of bowel

obstruction.b. To accurately differentiate between partial and complete small bowel obstruction.

. Some patients with partial SBO suffer serious morbidity and mortality from unnecessaryoperation.

. The etiology of the small bowel obstruction influences the clinical outcome.

ostoperative bowel obstruction, often conservative management is suc-


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essful. However, if operation is required, it is preferable to proceedefore the 14- to 16-day period when adhesions appear to be the mostenacious, poorly defined, and vascular. For patients with a low-gradeartial obstruction, it is preferable to wait for a 3-week period to do aomplete lysis of adhesions when the adhesions have softened and arelmy and less vascular. The incision should be a generous midline

ncision made over the previous incision but extended down to virginbdomen if there is an area that has been previously unoperated. Ineneral, the abdomen should be entered through the easiest part of thebdominal wall, which is usually the unoperated area. The incision shoulde extended slowly through the previous scar tissue using a scalpel. Usef a Bovie electrocautery in this setting is treacherous and riskshermal injury to bowel and an enterotomy. As the incision is carriedown to the scar tissue, entering the abdomen in the unoperated areaill allow the surgeon to place his or her hand inside of the abdomen

nd palpate the undersurface of the abdominal wall to check for anyowel loops that are adherent and at risk during the opening. Visuallynspecting the undersurface of the abdominal wall is often a good idea ifhe abdomen is open enough. As the abdominal cavity is entered,issecting the midline contents away from the scar must be done in aeticulous fashion using Metzenbaum scissors or a scalpel. Blunt

issection with dense scar tissue is unwise, and tearing the bowel is aikely result. After the abdomen is entered and midline adhesions takenown, the massively distended small bowel should be eviscerated so thathe site of obstruction may be identified. The offending adhesive bandhould then be divided, as well as any other bands that appear to beontributing to the obstruction.This part of the operation is the point at which viability of the bowel is

ssessed. If the bowel is pink, edematous, and somewhat thickened, itbviously is at low risk for ischemia. However, if the bowel is deeplyyanotic, thickened, or is a concern, time must be taken to assess theiability (Fig 6). Initially, placing a warm laparotomy pad over the bowelor 5 to 10 minutes is indicated. If the bowel remains cyanotic anduestionable, a Doppler ultrasound brought onto the operating field cansually assess whether arterial pulses are present. If arterial signals areresent, and there is no evidence of venous thrombosis, merely observinghe bowel for another 10 to 15 minutes is indicated before making aecision. If the assessment is still uncertain, administration of fluoresceinye intravenously with use of a Woods lamp is helpful in assessinghether the injured section of bowel has blood supply. Obviously, the

forementioned maneuvers are conducted if a large area of the bowel is


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nvolved. If a much shorter segment of small bowel is involved, merelyesecting that segment may be prudent. If the adhesions are diffuse, andsingle transition point is not identified, it is likely the surgeon will have

o do a complete lysis of adhesions from ligament of Treitz to theleocecal valve. In this setting, a few simple rules are helpful. First, thedhesiolysis should proceed from the easiest portion of the dissectionhere the adhesions are filmiest and the bowel most easily identified,

nd work to the more difficult areas. If serosal rents occur, they shoulde sutured with absorbable suture. Any enterotomies that occur duringhe course of an extensive adhesiolysis should be immediatelyversewn with plans to do a definitive closure at another time. Thishould minimize the amount of contamination. During this portion ofhe dissection, the bowel should be kept warm and moist to minimizeesiccation injury. In general, filmy adhesions can be separated largelyy blunt dissection, but dense thick adhesions should always be takenown sharply.A question often arises regarding dissecting obstructed bowel stuckown into a scarred pelvis. In most cases, it is wise to take the time andffort to dissect the bowel out of the pelvis even though it may requireesecting part of the bowel so freed. Bypassing large segments of smallowel has generally been associated in the past with clinical problems.After the small bowel has been freed up throughout its entire length, it isise to decompress the bowel before closure to both improve blood flow to

he bowel and make abdominal closure easier. The simplest way to manageecompression is to place the bowel between the second and third fingers,nd while gently squeezing, milk the fluid back up into the duodenum wherehe NG tube has been passed. In this fashion, the entire length of the bowelan be slowly decompressed. One must be careful during this decompressionrocess not to treat the bowel in a rough fashion because it is likely to resultn serosal splitting and hematoma formation. Occasionally, a small bowelesection is required during this process, and decompression can be accom-lished during the course of constructing the anastomosis by use of a suctionip placed through the enterotomy used for the anastomosis.If the patient has had only 1 or 2 previous laparotomies for lysis of

dhesions, at this point closure is indicated. In those patients who have hadmultitude of SBOs with multiple laparotomies, placement of a Baker tube

long intestinal tube with inflatable balloon at the end) is indicated. Beforelosure, placement of the omentum between the freed small bowel andbdominal wall is indicated. With the advent of antiadhesion barrier materi-ls, a prudent thing to do at this point is lay down a couple of sheets of the
ntiadhesion material so that reentry into the abdomen will be facilitated

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hould a subsequent laparotomy be required. Before closure in whichxtensive adhesiolysis is required, it is wise to carefully run the smallntestine from ligament of Treitz to ileocecal valve to look for any evidencef missed enterotomies or deep serosal rents. They can be repaired at thisime. Fascial closure is then performed in the standard fashion with closuref the skin usually possible.

aparoscopic Treatment of SBO

ntroductionWhen a surgeon is asked what procedures he or she performs laparo-

copically, many operations may be included, but until recently, fewould place exploration for bowel obstruction on the list. Indeed, the

gold standard” approach to bowel obstruction is still considered by manyo be open surgery. Slowly this trend is changing as more experience isained with advanced laparoscopic surgical procedures.Various forms of laparoscopic surgery have been performed for years.efore the advent of the computer chip digital camera, the operative fieldas able to be visualized only by the operative surgeon, who held the

aparoscope in 1 hand and operated with the other. The first reports ofaparoscopic surgery for adhesiolysis were in the gynecologic literature,ostly for infertility due to fimbrial or fallopian tube adhesions. Theseere usually localized pelvic adhesions. Early laparoscopy was limited by

he fact that the surgeon was required to hold the laparoscope to the eye,nd could work with only 1 hand. The assistant could blindly hold annstrument for retraction, but could not view the operative field.After the computer chip digital camera was coupled to the laparoscope in

he 1980s, the entire operative team was able to visualize the operative field,nd the modern era of laparoscopic surgery was born. In the early days ofaparoscopic surgery, it was believed that adhesions were a contraindicationo performing the procedure laparoscopically. As the skills of the laparo-copic surgeon improved, and as the equipment became better, more difficultrocedures could be performed. Surgeons became accustomed to lysingdhesions during other surgical procedures, and adhesions became a “relativeontraindication” to laparoscopic surgery. In 1991, Bastug and colleaguesrst reported laparoscopic adhesiolysis for SBO secondary to abdominaldhesions.55

Bowel obstruction occurs for a variety of reasons, including adhesions,ncarcerated hernia (incisional, umbilical, or groin), internal hernia (espe-ially in the era of laparoscopic gastric bypass surgery [Fig 29]), obstruction
rom cancer, diverticulitis, or foreign body (bezoar, gallstone ileus, or ingested

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oreign bodies). All the aforementioned can initially be approached via laparos-opy.The most obvious advantages of performing laparoscopy rather than open

urgery for SBO include avoiding laparotomy, and therefore the postlapa-otomy recovery, as well as minimizing the postoperative risks of laparoto-y-related adhesions and ventral hernia. Even if it becomes prudent to

onvert to an open operation (cancer-related adhesions or inability toechnically complete the operation laparoscopically), the eventual laparotomyncision may be limited based on the laparoscopically diagnosed location ofhe problem.An initial laparoscopic approach can allow for access away from theidline incision to minimize enterotomy of bowel adherent to a previousidline laparotomy. Even if a later conversion to open surgery is

equired, the adhesions might be able to be laparoscopically cleared fromportion of the midline incision, allowing for safer open access. With the

reation of pneumoperitoneum, the bowel tends to hang from the abdominalall, creating natural traction on the adhesive bands. The tented abdominalall acts to create countertraction. This effect can be enhanced for adhesionsff the midline by tilting and rotating the table to maximize this effect. Inmall condensed spaces, the laparoscope can be brought in close to the tissueso be lysed, and the magnified view may facilitate better visualization (Fig

IG 29. Laparoscopic view of internal hernia in a patient after gastric bypass. Retractor is holding uphe Roux Y limb under which the internal hernia occurred. (Color version of figure is available online.)

0). If localized dense adhesions are encountered that cannot be lysed


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aparoscopically, direct conversion to limited laparotomy can be performed inases in which there is adhesion-free bowel proximal and distal to the pointf obstruction.Advantages of laparoscopic surgery are well known, including faster returnf bowel function (shorter postoperative ileus), less postoperative pain,horter length of hospital stay, lower wound infection rate, and a reduced riskf wound dehiscence or postoperative incisional ventral hernia. It is wellocumented that laparotomy is an independent risk factor for formation ofostoperative adhesions, and the laparoscopic approach may limit recurrencef SBO. Schnuriger and colleagues found that in most abdominal procedures,he laparoscopic approach is associated with a significantly lower incidencef adhesive SBO or adhesion-related admission than in the open approach.56

hey performed a collective review of recent literature and found that thencidence of adhesion-related readmissions was 7.1% in open vs. 0.2% inaparoscopic cholecystectomies, 9.5% in open vs. 4.3% in laparoscopicolectomy, 15.6% vs. 0% in laparoscopic total abdominal hysterectomy, and3.9% in open vs. 0% in laparoscopic adnexal surgery. Only in appendec-omies was there no difference between the 2 techniques. They believed thatechniques that avoided unnecessary peritoneal dissection, and spillage ofntestinal contents, led to reduced adhesions. Weibel and Manjo noted that

IG 30. Excellent view of adhesions seen through the laparoscope. Lysis with “cold” scissors can beafely done in this setting.

atients undergoing laparotomy for various reasons have a 90% risk of


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eveloping intraperitoneal adhesions.57 The incidence of readmissions di-ectly related to those adhesions varies from 5% to 20%.

omparison of Open and Laparoscopicreatment of SBOOne of the earliest large series of laparoscopy for SBO was conductedy Franklin and colleagues.58 The authors reported a single-institution0-year retrospective review of patients who underwent laparoscopicperation for SBO from 1991 to 2001. A total of 167 patients underwentaparoscopy for diagnosis and/or treatment of intestinal obstruction. Thenvestigators used laparoscopy to successfully diagnose the site ofbstruction in all patients. The procedures were performed by pioneers inaparoscopy. They reported that all cases (of SBO) were approachedaparoscopically regardless of etiology, excluding patients with a priornown abdominal cavity that would make the laparoscopic approachnfeasible, such as concrete abdomen or known massive adhesions. Theites of obstruction were found to be stomach in 7 (4.2%), small bowel in16 (69.5%), and colon in 44 (26.3%) cases. The causes of obstructionncluded adhesions (30.7%), abdominal wall hernias (26.7%), adenocar-inoma of the colon (13.1%), Crohn’s disease of the small bowel (5.1%),olonic diverticulitis (5.1%), internal hernias (3.4%), ischemic or radia-ion-induced colitis (3.4%), colonic volvulus (2.3%), benign colonicumors (1.1%), gallstone ileus (0.6%), and ileocecal intussusception0.6%).Approximately 154 patients (92.2%) were successfully treated laparo-

copically without conversion to laparotomy. The conversion rate was.8%. Inability to visualize and control the operative field because of aassively dilated bowel was the most common cause of conversion

46%), followed by extensive involvement of surrounding structures byumor (23%), dense adhesions that could not be managed laparoscopically15%), significant intestinal ischemia with necrosis (8%), and an iatro-enic bowel injury in 1 patient that could not safely be repairedaparoscopically (8%). Operative time varied from 20 minutes to 3 hours.he intraoperative complication rate was 3.5% and consisted of inadver-

ent enterotomies in 6 patients, 5 of which were repaired laparoscopically.he average return of bowel function was at 2 days (range 1-8), andverage postoperative stay was 5 days (range 2-42). The postoperativeomplication rate was 18.6%. Complications included prolonged ileus4.8%), wound infection (4.2%), and septic complications (2.9%). Theverall recurrent obstruction rate was 4.2%, consisting of one case in the
mmediate postoperative period, and 6 delayed cases. Of the 6 delayed

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ases, recurrent adhesions occurred in 3, recurrence of cancer in 2, andadiation-induced stricture in 1. The perioperative death rate was 2.3%cause of death was not specified). The authors summarized that alluspected cases of intestinal obstruction can be approached initially byaparoscopy, and the vast majority can be treated without conversion.hey stressed the importance of advanced laparoscopic skills and instru-entation.In a large multicenter retrospective study, Levard and colleagues

etrospectively reviewed records from 308 patients with SBO treatedaparoscopically in 35 centers from 1986 to 1998. Approximately 40atients (13%) had not had previous abdominal surgery, 159 patients59.3%) had undergone 1 previous abdominal operation, and 79 patients29.4%) had undergone 2 operations.59 The initial onset of symptomsegan 48 hours before hospitalization, and the patients underwent surgeryn average 1 day after admission (range: 2 hours to 12 days). Theyeported a 54.6% success with laparoscopic surgery, a 40.9% failureequiring immediate conversion, and a 4.5% short-term failure rateequiring a return to OR an average of 4 days after the initial procedurerange: 1-12 days). Success was noted to be higher in patients who onlyad a previous appendectomy with obstruction due to localized adhesionsnd in those with no antecedent surgery. Success was lower in patientsith multiple dense adhesions. The 2 most common causes for conversionere intestinal necrosis in 22.8% of failures (10.3% overall) and intestinal

njury in 18% of failures (8.4% overall). The reason for delayedonversions was mainly due to persistent obstruction or peritonitisecondary to leak of repaired intestinal injury or intestinal necrosis. Earlyeath rate was 1.1% in the patients who completed laparoscopically, and.6% in the converted patients. The postoperative ileus rate was 2 days inhe laparoscopic group, and 4 days in the open group. Wound complica-ions in the laparoscopically completed group occurred in 2 patients1.2%) and in 15 patients (10.7%) in the converted group. Hospital lengthf stay was 4 days in the laparoscopic group and 10 days in the openroup. The average follow-up was 1.6 months (range: 1-78 months).ecurrent obstruction was noted in 5% of each group.The authors suggest that factors making laparoscopic surgery moreifficult than open surgery include reduced operative space and difficultyith anterograde or retrograde voiding of the intestinal contents (ie,ilking out the intestinal contents). They also recommend that laparo-

copic treatment should probably be limited to patients who havendergone fewer than 3 previous abdominal operations. They favor the
aparoscopic approach in patients with previous appendectomy or patients

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uspected to have adhesive bands rather than dense adhesions. Theuthors suggest that conversion may be related to the learning curve, asnly 11 of 43 centers had performed more than 10 laparoscopic lysis ofdhesion cases. The follow-up in this study was short, and thereforentermediate and long-term recurrence rates cannot be determined basedn this report.Lujan and colleagues performed a retrospective review of 61 consecu-

ive patients who underwent laparoscopic exploration for SBO between998 and 2003.60 Diagnosis was made by gastrograffin upper gastroin-estinal (UGI) study or CT scan, or both. All patients had a tight partialBO or a complete SBO. Patients were excluded if they had free air orvidence of malignant causes of obstruction. Approximately 15% of theatients had no previous history of abdominal surgery, whereas 85% hadprevious abdominal operation. Two thirds of the cases were able to be

ompleted laparoscopically. Of the 33% patients reportedly converted topen operation, 7 of 20 were converted to “mini open”—referred to byther authors as a “laparoscopic assisted operation.” Only 13 of the 61atients (21%) required a full laparotomy while the most common causef obstruction was a single band. The single band cases were shortanging from 12 to 60 minutes (comprising 41% of the cases). The statedeasons for conversion included massive or dense adhesions, ischemicowel, iatrogenic enterotomy, and technical difficulties. Three patients inach group had an iatrogenic bowel injury, which did not reach statisticalignificance. The mean length of stay was 3.9 days in the laparoscopicroup vs. 8.5 days for the mini-open and 11 days for laparotomy.The authors believed that less emphasis should be placed on the fear of

onversion and that laparoscopy should be incorporated into the algo-ithm for these patients. They contend that conversion does not equalailure, but simply the necessary sequence of events in the optimalanagement of these patients. They conclude that any surgeon with

dvanced laparoscopic skills who has performed a standard midlinencision to release a single adhesive band, regrets that the operation waserformed in an open fashion when it could have been performedaparoscopically, often with only 3 5-mm ports.Zerey and colleagues performed a retrospective single-institution re-iew of all patients undergoing laparoscopic adhesiolysis between 1997nd 2006.61 All 33 laparoscopic operations were performed by experi-nced laparoscopic surgeons. They reported that contraindications to aaparoscopic approach were massive distension, a firm scarred abdomen,r peritonitis. They noted that 66.6% of the patients treated laparoscopi-
ally had significant distension. The authors were able to diagnose the site

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f obstruction laparoscopically in all patients. Approximately 88% werereated laparoscopically, and 12% required conversion to open operationecause of either dense adhesions or insufficient working space. Ofnterest, all 4 conversions occurred in patients with only 1 previousbdominal operation, and the authors found no statistical difference inuccess based on number of operations. The mean procedural time was00 minutes (range: 19-198), and there was no difference in blood lossetween the 2 groups. There was 1 intraoperative complication (3%), annterotomy, which was repaired laparoscopically. There were 7 postop-rative complications (21.2%), including urinary tract infection (2),ound infection (2), renal insufficiency (1), congestive heart failure (1),

nd pseudomembraneous colitis (1). The average return to bowel functionas 3.2 days (range: 1-6), and the average hospital length of stay was 6ays (range: 1-19) in both the laparoscopic and converted groups.The authors identified several clinical predictors for the successful

aparoscopic management of adhesive SBO, including SBOs that tempo-arily resolve after placement of a NG tube, but recur when the patient ised, patients in whom the abdomen is not very tightly distended, patientsith proximal bowel obstruction, patients with previous operative treat-ent in a limited area of the abdomen, and patients whose last operationas more than 1 year before the SBO. They also stated that success wasredicated on the ability to gain safe access to the peritoneal cavity, andbility to initially insufflate more than 1 L of CO2. Success was also moreikely if the obstructed segment was not fixed to the retroperitoneum.In this study, the authors described a possible selection bias for

aparoscopic surgery primarily in patients who had previous surgery in aimited area of the abdomen. They noted that there were no significantifferences in the proportion of patients who had a single band as thetiology of the obstruction compared with multiple adhesions in theatients who underwent laparoscopic surgery.In another single-institution study of 285 cases of SBO, Chopra and

olleagues noted that 75 were due to adhesions, 34 of these 75 cases werettempted laparoscopically, and 23 (68%) could be completed laparo-copically.62 Of the 11 patients converted to open surgery, the causesere dense adhesions (4/11), inability to find the point of obstruction

4/11), inability to achieve pneumoperitoneum (2/11), and ischemicowel (1/11). There was 1 intraoperative bowel injury in the laparoscopicroup, and 10 in the open group (4.6% in the laparoscopy group, 19% inhe open group). However, the converted patients were crossed over to thepen group, and it was not specified whether any of these bowel injuries
ere in the converted group, or, if so, when the injury occurred. The

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nterotomy rate did not reach statistical significance in either group.owel resection rates were 4.3% in the laparoscopic group, 9% in theonverted group, and 22.6% in the open group. The operative times were.3 hours in the laparoscopic group, 3.4 hours in the open group, and 3.9ours in the converted group. Morbidity was 39% for the laparoscopicroup, 74.5% in the open group, and 63% in the converted group. Thesencluded prolonged ileus in 8.7% of laparoscopic group and 40.4% in thepen group, pneumonia in 9.6% of the open group, but none inaparoscopic group. One patient in the laparoscopic group required openeoperation for unresolved SBO. The laparoscopic group had significantlyecreased OR time, less blood loss, and shorter length of stay.The authors stated that the overall number of complications contributing

o morbidity were significantly lower in those who underwent laparo-copic adhesiolysis, and morbidity was unchanged in the converted grouphen compared with the open group. They concluded that it is important

o maintain a low threshold for conversion to laparotomy to preventatrogenic injury to friable or distended bowel.In a retrospective study of the authors’ experience with laparoscopic

reatment of SBO during a 6-year period, Tierris and colleagues reportedn 32 patients with SBO who underwent elective laparoscopic treatmentfter a failure of conservative measures.63 Laparoscopic surgery waserformed after 3 to 4 days of nonoperative management in patientsithout peritoneal signs, or rising white blood counts. Adhesions were

dentified in 62.5% of patients. The conversion rate was 18.7%: 2 patientsor excessively dense adhesions, 2 for iatrogenic intestinal perforation,nd 2 for inability to relieve the obstruction laparoscopically. The meanR time was 78 minutes, and only 1 postoperative complication occurred

3.25%), which was due to unrecognized iatrogenic bowel injury neces-itating a laparotomy. The average time to return of bowel function was.2 days, and length of stay averaged 4.6 days. The authors believed thatT scan proved to be helpful in the diagnosis and localization of thebstruction.In the pediatric literature, Aguayo and colleagues performed a retro-

pective review of 34 laparoscopic procedures for SBO between 2001 and008.64 The mean age was 8.1 years (range: 2.3-14). The most commonause was postoperative adhesions, in 73.5%. Approximately 32% ofatients required conversion to laparotomy because of poor workingpace, intestinal volvulus, or inability to identify source of obstruction, ornterotomy. There was a 9% enterotomy rate.Recurrent bowel obstruction occurred in 14.7% of patients in the

dhesiolysis group, with a mean time to recurrence of 2.6 months.


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nterestingly, the recurrences were in the laparoscopic group, and noecurrence occurred in the open group. Follow-up was only a mean of 7.3onths, and this recurrence rate did not reach statistical significance. The

uthors stated that in patients who required conversion, the laparoscopicvaluation did aid in identifying the etiology of the obstruction, andllowed a directed surgical approach when appropriate.Ghosheh and Salameh65 reviewed the literature for laparoscopy andowel obstruction evaluating 19 studies from 1994 through 2005 (Table). Laparoscopy for acute SBO was performed in 1061 patients. Theauses of SBO were reportedly adhesions (83.2%), abdominal wall hernia3.1%), malignancy (2.9%), internal hernia (1.9%), and bezoars (0.8%).he overall success rate was 66.5%. A total of 705 cases were completedither laparoscopically or in a laparoscopic-assisted fashion, as theyncluded patients requiring a small targeted incision for limited bowelesection or repair of enterotomy. Conversion to laparotomy was requiredn 33.5%. The reasons for conversion in these 365 patients included densedhesions (27.7%), need for bowel resection (21.3%), unidentified etiol-gy (13.0%), iatrogenic injury (10.2%), inadequate visualization (4.2%),ernia (3.2%), and other causes (11.1%).The total number of patients with enterotomies was 45 (6.5%), but

ess than one half required conversion. There were, however, 9 missederforations, including 1 trocar injury. Early recurrence of SBOdefined as within 30 days) was 2.1%. Only 7 of the 19 studieseported long-term outcomes ranging from 24.4 to 61.7 months, andherefore long-term recurrence rates cannot be determined. Of thosetudies, 162 of 223 patients’ operations (72.6%) were completedaparoscopically; 17 patients (7.6%) had SBO in the longer follow-uperiod.Morbidity and mortality rates were 15.5% and 1.5%, respectively. The

ABLE 7. Series of laparoscopic exploration for small bowel obstruction (SBO)

Author NumberConversion

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ranklin58 167 8% Massive dilation 22% 2 5evard59 308 41% Intestinal necrosis 10% 2 4ujan60 61 33% Massive adhesions — — 3.9erey61 33 12% Massive dilation 24% 3.2 6hopra62 285 32% Dense adhesions 39% — —ierris63 32 19% Dense adhesions 4% 3.2 4.6hosheh65 1061 33% Dense adhesions 15% — —

uthors stated that this rate compares favorably with open series listing


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orbidity rates as high as 32% and mortality as high as 3.8%. However,hey also added that selection bias in these nonrandomized trials may wellccount for this difference. They also summarized that in contrast to openanagement, which traditionally involves extensive adhesiolysis, no

ttempt is generally made during laparoscopic management to take downhe entire abdominal wall and intraloop adhesions. Instead, only thedhesions impeding exposure, and those causing the obstruction arereated.In a survey of 87 surgeons in Connecticut regarding opinions onperative management of adhesive SBO (laparoscopy vs. laparotomy),4% believed that laparoscopy had a role in the management ofdhesive SBO, 71% believed it was safe, and 60% of the surgeonsnswering the survey do perform laparoscopic lysis of adhesions inheir practice.66 However, only 68% of this group use this techniqueor more than 15% of their adhesive SBO cases (ie, 40.8% of the totalroup use it for more than 15% of adhesive SBO). The survey foundhat surgeons more recently trained or with membership to minimallynvasive surgery associations were more likely to use laparoscopicysis of adhesions.In the colorectal literature, Franko and colleagues67 performed a

etrospective study to ascertain the impact of previous abdominal opera-ion in patients presenting for laparoscopic colorectal surgery. Theuthors were interested specifically in the impact on conversion andomplication rates. Charts from 1000 consecutive laparoscopic colorectalases were reviewed. The past surgical history was available on 820atients, and a previous abdominal operation was present in 347 patients42.3%). Overall, there was a higher conversion rate to open operation inhe patients who had previous abdominal surgery (19.6% vs. 11.4%;verall 14.8% conversion rate). An increased risk of conversion wasoted in patients with a history of previous pelvic surgery (26% vs.3.7%). Previous appendectomy or cholecystectomy had no statisticallyignificant effect on conversion rates.The authors noted that in the patients with previous abdominal surgery,

here was a higher inadvertent enterotomy rate at 1.4% vs. 0.2%, higherostoperative ileus rate 6.6% vs. 3.0%, and a higher reoperation rate, at.3% vs. 0.2%. There was no statistical difference in operating time orlood loss between the 2 groups. There was no statistical difference inostoperative bowel obstruction, readmission, leak, abscess, woundnfection, intraoperative bladder or ureter injury, intraoperative significantleeding, or death. In this series, there was no difference if the patient had
nly 1 previous abdominal operation or several.

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echniques for Laparoscopic Surgery for SBOPositioning and Access. There are several techniques that may be used

o facilitate the laparoscopic approach. For the patient with a bowelbstruction, NG decompression before and during operation will helpinimize volume of air and fluid in the bowel, and decrease bowel

istension. The heavy fluid-filled bowel is difficult to handle as comparedith air-filled bowel. Similarly, bladder decompression with a Foley

atheter may improve space in the peritoneal cavity, and minimize theisk of bladder injury.Patient positioning can greatly affect the feasibility of the laparo-

copic procedure. The arms should be tucked at the patient’s sidesilaterally to allow for the assistant holding the laparoscope to standn the same side as the surgeon, preventing a “backward view” for thessistant. An electric table able to tilt in all directions can maximizehe effect of gravity pulling the bowel away from the distendedbdominal wall.Access to the peritoneal cavity should be obtained at a site removed

rom previous surgery. Most surgeons will access either the subcostal leftpper quadrant or the subcostal right upper quadrant based on which isore likely to be free of preexisting adhesions. Other choices could

nclude the umbilicus if previous midline incision has not been per-ormed. Initial access with Veress needle or optical trocar is the mostommon approach at the current time. A muscle splitting incision forpen port placement can be performed in the lateral abdomen in anyuadrant. A high flow CO2 insufflator will allow for maintenance ofneumoperitoneum.On initial assessment of the peritoneal cavity, if adhesions are exten-

ive, and preclude placement of a second port, gentle blunt dissectionith the telescope many times will clear enough space for placement of

he next port. Conversely, a port could be placed in another abdominaluadrant using the techniques described earlier in the text. The goal is toave at least 3 laparoscopic ports dispersed in a pattern to allowriangulation. Additional ports should be placed as needed.Use of an angled telescope is highly recommended to facilitate the bestiew in a tight space. A 5-mm angled scope allows placement in any port,nd is also recommended. Allowing gravity to help mobile bowel fallway and to pull down adherent bowel to place stretch on the adhesionss helpful. Tilting the patient as needed to maximize this effect is also
ecommended.

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echniques for AdhesiolysisTo manipulate tissue, atraumatic bowel graspers should be used torasp mesentery, omentum, or pericolic fat when possible. When theowel must be grasped, the tissue should be grasped as broadly asossible to spread the pressure, and minimize injury to the bowel fromhe instrument. Many adhesions are avascular and may be divided withold scissors. Once the leading edge of an adhesion is incised, a gentlerodding with a blunt instrument may be able to develop the plane, andesidual adhesions may then be lysed with the scissors. Energypplication should be used as sparingly as possible. When usingonopolar electrocautery, care must be taken to prevent direct injury

o the bowel. Use of harmonic instruments may generate a dissectionlane with the steam vapor created when the energy is applied to theissues, but the blade does become hot, and can injure the bowel.After a free peritoneal space is created, it is often easiest to work

rom terminal ileum in a retrograde fashion, or if this is not feasible,ork from collapsed bowel and run in each direction. This minimizes

he amount of manipulation of dilated bowel. After the obstructiveand or adhesions are lysed, many times the dilated bowel is able toecompress by expelling its contents into the distal collapsed bowel.omplete lysis is controversial. If the obstruction appears to be clearly

ound and lysed, the risk of bowel injury may override the benefitsotentially gained by lysing all remaining adhesions. It may beisadvantageous to divide nonobstructing adhesions only to have themeform in a more obstructive pattern. The patient can return to surgeryf needed for further lysis of adhesions.If an enterotomy is encountered, it may be repaired with suture if the

njury is small. If open repair or limited resection is required, a miniaparotomy either in the midline or as a muscle splitting incision can beerformed, precluding the need to convert to full laparotomy.If a transition zone is not clearly determined, it might be prudent to

onvert to open laparotomy. If adhesions are too dense to safely lyseaparoscopically, conversion to open surgery is recommended. If at anyime the surgeon feels uncomfortable proceeding laparoscopically, itould be prudent to convert to open operation. Conversion should not be

onsidered a failure of laparoscopic surgery, but rather the naturalrogression of an operation performed in the least invasive fashion that isafe and reasonable. In other words, conversion usually exemplifies sound
urgical judgment.

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onclusionsLaparoscopy as an initial approach to patients with SBO is slowly being

ccepted. It appears to be a safe initial approach, which, if completeduccessfully, may result in shorter length of hospital stay, quickerecovery, and less postoperative morbidity. Selection of appropriateatients is important, but there are ever-widening indications to begin arocedure laparoscopically.Initial port placement at a site remote to expected adhesions, using aariety of techniques, may limit the risk of access injuries. A methodicalpproach to patient preparation and positioning is important in minimiz-ng the need to convert to open operation. Surgical technique shouldnclude cold scissors and blunt dissection when possible, and applicationf energy should be used carefully and judiciously. One of the mostreaded complications in laparoscopic management of SBO is the risk ofnterotomy, which occurs 6.5% of the time. The real concern, however,s that this bowel injury may be missed at the time of operation, aomplication that can have devastating consequences. Although a missednterotomy can occur in association with laparotomy, the incidence isigher with laparoscopic surgery. The risk of bowel injury can beiminished by following good surgical technique, which includes avoid-ng the use of electrocautery, minimization of grasping dilated bowel,anipulation of the bowel using atraumatic graspers, and by handling theesentery whenever possible.67

Although not all of these operations can be completed laparoscopically,he ones that can may limit operative times. It is important to recognizehen it is not reasonable to continue a procedure laparoscopically, and to

onvert to open surgery. It should not be considered a surgical failure toonvert to open operation, as laparoscopic instruments and techniques arenly a portion of the tools available to a surgeon. The goal of any surgicalrocedure is for the patient to have a successful operative result with theeast invasion and risk. When it is not possible to achieve this laparo-copically, conversion to the open operation is part of the spectrum of aurgeon’s operative scope.

ontemporary Progress in Preventing Adhesive SBOKnowledge of adhesions extends back to ancient Egyptians who described

evere pelvic adhesions in a patient; no treatment was suggested.68 In a recenteview, as mentioned previously, Hunter knew about adhesions (mid 1700s),ryant reported a fatal case of adhesive bowel strangulation in the mid
800s,1 and use of salt solutions for hydroflotation of the bowels was

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escribed in the late 1880s. An agent called “fibrinolysin” (thiosinamine andodium salicylate) was introduced in 1892 but was found not to be effectivend soon fell into disfavor.1 Gum Arabic was recommended as a “lubricantetween the viscera” in 1902, and Johnson and Johnson marketed areparation of bovine cecal peritoneum that was commercially available wellnto the 20th century. Since then a wide variety of exotic substances haveeen used in an attempt to diminish postoperative adhesions, includingmental grafts, metal foils, gold-beater’s skin, shark peritoneum, lanolin,hyme, amniotic membrane, and fish bladder. The sheer number of agentstudied confirms their lack of efficacy in eliminating this troublesomeostoperative complication.In the study by Menzies and Ellis, the most common site of postsurgical

dhesions occurred between the omentum and the undersurface of thebdominal wall incision site.4 The second most common was small bowelo small bowel. However, the most common site of an obstructingdhesion almost always involved small bowel (85%) as opposed tomentum (3%)4 (Table 8). Operative procedures in the hypogastrium arelso more likely to result in adhesive obstruction than those in thepigastrium (Table 9). In the previously referenced study, appendectomy,ectal surgery, colon surgery, and gynecological procedures were the proce-ures most likely to result in clinically significant adhesive obstructions.There are few data available regarding the timing of onset of obstructive

dhesions. Stewart and others prospectively followed all laparotomyatients and found that at 1 month after operation, 0.5% had obstructionrom adhesions; at 1 year after operation, 1% of patients had obstructingdhesions.69 Most studies suggest that 15% to 20% of adhesive SBOccur within 1 month postoperatively, another 20% to 30% within the firstear, and another 20% in the next 1 to 5 years (Table 10). However,dhesive SBO can develop even at times remote from the original

ABLE 8. Location of postoperative adhesions

Adhesion site Number of patients

Omentum to incision site 170Operative site alone 57Omentum to operative site 47Small bowel to incision site 42Small bowel to operative site 33Small bowel to small bowel 17Other 31

eprinted with permission from Menzies and Ellis,4 © The Royal College of Surgeons ofngland.

rocedure, commonly exceeding 10 years. Studies vary, but between 36%


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nd 60% of all patients who present with an SBO require operation,70,71

nd after an operation for lysis of adhesions, the incidence of recurrentdhesive SBO leading to an operation ranges from 11% to 21%.72,73

Operative procedures to prevent recurrent SBO have been generallyisappointing and only occasionally successful. Suture plication has gener-lly had poor results and is used by few surgeons today. Somewhat moreuccessful has been an operatively placed Baker long intestinal tube, whichs passed through the stomach like a Stamm gastrostomy, traverses the entireength of the small intestine, and reaches the cecum where a 30 mL balloons filled with saline to prevent the tube from retracting back into the smallowel. Obstructive recurrence occurs in 3.3% to 8.0% of patients.74,75

dhesion PreventionA voluminous literature on adhesion prevention has been written,

ncluding reviews by Connolly and Ellis76,77 (Table 11, Table 12). In hiseview, Ellis suggested that the best way to prevent adhesions was to

ABLE 9. Previous operative sites producing adhesions

Operations performed Number

Appendectomy 12Rectal surgery 12Gynecological surgery 11Left colon 8Total colon 7Right colon 4Cholecystectomy 4Duodenal ulcer 4Unknown 8Other 10


ABLE 10. Interval from operation to adhesive obstruction

Interval from operation Percent

�1 mo 211 mo-1 y 171-5 y 215-10 y 6�10 y 21Unknown 12


inimize trauma during surgery: (1) avoid introduction of foreign


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aterial (talc, etc), (2) leave raw serosal areas open, (3) cover injuredreas with viable tissue, such as omentum, and (4) place omentum behindhe abdominal wall incision. Additional suggestions should includereventing serosal desiccation with moist lap pads, use of woundrotectors, gentle handling of peritonealized structures, and meticulousissection in as small an area as possible.Strategies for preventing adhesions have generally fallen into the

ategories listed in Table 13. A review of the experimental work done inach of these areas is appropriate and helpful to understand the difficultyn solving this clinical conundrum.

rrigantsAs previously mentioned, both normal saline and lactated Ringer’s

ABLE 11. History of attempts to prevent adhesion

1885 Rubbing oil used to prevent adhesions

1886 Saline hydrofloatation described1892 “Fibrinolysin” (sodium salicylate and thiosinamine) marketed1902 Gum Arabic used as visceral lubricant1905 “Cargile” (bovine cecal peritoneum) introduced1920 Intra-abdominal proteases described1940 Heparin first studied1957 “Amfetin” (amniotic fluid) marketed1994 “Seprafilm” studied in prospective randomized trial

ABLE 12. Other agents used to diminish adhesions

Oral phosphorus Shark skin

Collodion LanolinPhysostigmine ChymeLiquid petroleum Fish bladderOmental grafts PeritoneumMetal foils Gold-beater’s skin

ABLE 13. Strategies for preventing adhesions

IrrigantsAnticoagulantsAnti-inflammatoriesFibrinolyticsCellular modificationBarrier agents

olution have been used to fill the peritoneal cavity at the end of a case.


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he presumption has been that “floating the bowels” would prevent thenjured serosal surfaces from coming in contact with each other, thusreventing adhesion formation. More than 20 studies have been con-ucted evaluating “hydroflotation” as a method to reduce adhesionsostoperatively. In the meta-analysis of the aforementioned studies,iseman and colleagues reported that no significant difference was seen

etween control and experimental groups.78

nticoagulantsA large number of studies have been conducted to assess the efficacy of

nticoagulants in preventing adhesive SBO. A number of investigationsave evaluated dextran 70 as a possible antiadhesion irrigant. Theeneficial effects of dextran were observed in several animal studies.ndeed, 2 prospective clinical studies in humans demonstrated somefficacy of dextran in preventing pelvic adhesions, which cause infertil-ty.79,80 However, an equal number of studies have demonstrated nomprovement with dextran,81,82 and because of possible serious sideffects, dextran is not commonly used in adhesion prevention today.Similarly, intraperitoneal heparin has been extensively studied to

valuate its potential antiadhesion effect. Initial studies in animalsuggested that intraperitoneal heparin might be effective, but humantudies with heparin were disappointing and were complicated byleeding complications.82,83

nti-Inflammatory AgentsNonsteroidal anti-inflammatory agents were shown to reduce peritoneal

dhesions in a variety of animal models. However, Nishimura andolleagues and Holtz demonstrated that ibuprofen had no impact wheniven to humans postoperatively.84,85 Generally, NSAIDs have beennpredictable and erratically effective.Corticosteroids were shown in animal and humans to reduce postoper-

tive adhesions.86-88 However, intraperitoneal steroids in human studiesave had mixed and unpredictable results in work done by Glucksmannd colleagues and Seitz and colleagues.87,89 In addition, use of steroidsn a postoperative situation is limited by immunosuppression and delayedound healing.

ibrinolyticsFibrinolytic preparations would intuitively seem like the ideal agents torevent postoperative adhesions. Both streptokinase and urokinase have
een shown to have some impact on adhesion formation,90,91 but further

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tudies have been disappointing,92,93 and the surgeon worries about thempact of such preparations on anastomotic and fascial wound healing.Recombinant t-PA has been shown to diminish adhesions in animalodels without having a detrimental effect on wound or anastomotic

ealing.94,95 However, other studies revealed that adhesions still devel-ped at the site of colonic anastomoses and ischemic small intestine.96

learly, this agent must be studied more thoroughly in humans and holdsome promise as a future antiadhesion agent. Currently, most investiga-ors agree that the balance between t-PA and t-PA inhibitors (PA-I) holdshe key to successful treatment of obstructive adhesions in the future. Fearf bleeding, anastomotic disruption, and wound dehiscence have furtherimited the use of fibrinolytic agents.

arriersThe area in which the greatest strides have been made in adhesionrevention in the past 15 years is that of barriers that separate the variousnjured serosal surfaces while they are healing. The concept is simple butuite effective: placement of a mechanical barrier between the injuredealing serosal surfaces, which persists until all serosal healing has takenlace, will prevent adhesive bowel obstruction. An added advantage ofhis approach is that it should have little impact on the normal healingechanisms, and if the agent is inert, nonreactive, and absorbable, there

hould be little associated morbidity. Several products in membrane formave been used clinically to obviate adhesions after lower abdominal orelvic operations. There are also a few liquid or gel preparations that haveeen tested.

yaluronate/CarboxymethylcelluloseBy far, the membrane tested most extensively in adhesion prevention ishyaluronic acid/carboxymethylcellulose preparation marketed as Sepra-lm (Genzyme, Cambridge, MA). This somewhat brittle membrane isbsorbed within 7 to 10 days after placement in the abdomen, andxcreted within a month. It has been extensively studied for safety andfficacy in a number of clinical studies and appears to have very few, ifny, side effects except some questions of a slightly increased risk fornastomotic leak if wrapped entirely around a fresh anastomosis. A hostf retrospective and prospective randomized studies have been conductedo ascertain whether it decreases adhesions. The earliest study by Beckernd colleagues was prospective and randomized with adhesion assess-ent by blinded observers.88 Approximately 175 patients who underwent

leal-pouch anal anastomosis (IPAA) and protective loop ileostomy were


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andomized to receive the membrane or not, and adhesion evaluation wasonducted at the second-look laparotomy to close the ileostomy 8 weeksater. The authors reported significantly fewer and less severe adhesionsn the membrane group.In a group of patients undergoing rectal surgery who needed an

leostomy, Tang and colleagues randomized patients who would seektoma closure into membrane vs. no membrane groups. At the secondperation, the authors encountered fewer and less severe adhesions in theembrane group and fewer stoma complications (mean adhesion score

.81 � 0.5 vs. 7.82 � 0.6, P � 0.05). The authors of both this and therevious study observed that the dissection was much easier in the membraneroup.97 Similarly Vrijland and colleagues prospectively randomized aroup of 71 patients undergoing a colorectal resection with Hartmannsnto membrane and no-membrane groups. At operation to close the stoma,

blinded evaluator assessed the field for incidence, severity, andomplications of adhesions. The investigation reported a significantecrease in severity but not incidence of adhesions (OR, 0.34; 95%onfidence interval, 0.06-1.98).98

A Canadian group led by Cohen in a prospective multicenter trial usedhe model of the original group to randomize IPAA patients intoembrane and control groups. The membrane used in this study waseprafilm with glycerol added to make the membrane softer, pliable, and

ess brittle. Using laparoscopy at the time of ileostomy closure, adhesionsere graded according to incidence and severity. The investigators

eported a significant decrease in incidence and severity in the membraneroup.99 A similar prospective randomized study by Kusunoki andolleagues was conducted in patients who needed a protective ileostomyfter low anterior resection. During stoma closure, the severity ofdhesions was assessed and found to be significantly reduced in both theeristomal area and posterior midline. Once again the authors commentn shorter surgical time and less blood loss.100 Finally, a Cochrane reviewonducted by Kumar and colleagues evaluating 6 randomized trials usingeprafilm revealed that use of the membrane significantly reduced thextent and incidence of adhesions.101

Although the early studies of Seprafilm were conducted to ascertain theembrane’s efficacy in reducing adhesions, they were not designed to

ssess impact of the membrane on actual SBO. The most important studyn the literature, which truly assessed the impact of the hyaluronate/arboxymethylcellulose membrane on actual bowel obstruction, wasublished in 2006. In a prospective, randomized, multicenter trial
nvolving 1791 patients, Fazio and colleagues designed the study so that

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eprafilm was liberally placed at every site serosal or peritoneal injuryccurred (instead of merely placing it between the abdominal wall andmentum as in the early studies). The authors followed their patients for.5 years and found that although the overall incidence of SBO was notiminished in the membrane group, the incidence of SBO requiringurgical treatment was significantly lower (1.8% vs. 3.4%; P � 0.05).102

n a second nonrandomized study by Kudo and colleagues in patientsndergoing AAA repair, the incidence of SBO was 0% in the Seprafilmroup and 20% in the no-membrane group (P � 0.05).103

Thus, the debate regarding use of Seprafilm to prevent SBO continuesTable 14). What can be said is that Seprafilm reduces the incidence andeverity of postoperative adhesions and clearly makes abdominal reentryt a second procedure much easier. Considerations should be given tolacing it in the abdomen of any patient for whom the surgeon plans oneoperation for any reason.

xidized Regenerated CelluloseA preparation consisting of oxidized regenerated cellulose was therst antiadhesion barrier to be FDA approved. Marketed under theame Interceed, this agent changes to form a gel-like material whenoming in contact with peritoneal fluid. The gelatinous materialersists during adhesion formation and is finally excreted 14 days afterlacement.In a prospective randomized study, Azziz performed laparotomy on34 patients for lysis of adhesions and placed Interceed on one pelvicidewall and nothing on the other side. At a second-look laparoscopy0 to 98 days later, the incidence and severity was found to be muchiminished in the experimental group with the membrane.106 Simi-arly, Larsson and colleagues studied Interceed in a prospective,andomized, multicenter trial in which 66 women had lysis of

ABLE 14. Efficacy of Seprafilm in reducing small bowel obstruction (SBO)

Author JournalStudytype

Patientno.

Incidence ofSBO (%)

(Con vs. Rx)

Re-operationfor SBO (%)(Con vs. Rx)

Septiccomplications(Con vs. Rx)

azio102 DCR PRCT 1701 12 vs. 12 3.4 vs. 1.8* 3 vs. 4alum104 DCR Retro 438 6.1 vs. 4.5 3.9 vs. 1.5 1.1 vs. 3.4ottri105 Am Surg Retro 368 14.2 vs. 6.5* 4.4 vs. 1.6 13 vs. 15udo103 Surg Today Retro 51 20 vs. 0* — —

p � 0.05.

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ellulose preparation, and used nothing on the opposite side. At 4 to 10eeks after laparotomy, a second-look laparoscopy was performed,hich revealed a significant reduction in the incidence and severity of

dhesions on the membrane-wrapped side.107 A host of smaller studiesnd 2 meta-analyses108,109 confirm that Interceed reduces the inci-ence and severity of adhesions in women undergoing pelvic surgery.Unfortunately, experimental trials have shown poor results of

nterceed in the presence of blood and/or infection,110 and mosttudies with this product have been conducted in women withnfertility problems. Because there does not appear to be significantlinical benefit in preventing SBO, Interceed is rarely used by generalurgeons today.

xpanded PolytetrafluoroethylenePolytetrafluoroethylene is widely used in vascular surgery and has beensed to prevent pelvic adhesions in women with adhesion-related infer-ility. It is an extremely inert nonabsorbable membrane that generatesinimal inflammatory reaction after placement. The membrane is occa-

ionally used in the repair of pericardium or peritoneum and has beenxperimentally shown to reduce adhesions.111 Marketed as Preclude, oneW.L. Gore & Associates, Inc, Newark, DE) clinical study showed aeduction in postsurgical adhesions with its use,112 and its ability toeduce abdominal adhesions as part of a composite mesh materialDual-Mesh) in ventral hernia repair has been reported.113

However, like Interceed, most studies evaluating the efficacy of Preclude indhesion prevention have been in women with pelvic adhesion-relatednfertility. A major disadvantage of this product is that it must be removedventually and cannot stay in place on a permanent basis.

codextrinA 4% solution of icodextrin, a glucose polymer, has been used with

ome success in preventing adhesions. The solution is a less concentratedorm of the liquid used in peritoneal dialysis, 7.5% icodextrin. It is theost thoroughly studied and the only FDA-approved liquid antiadhesive

gent commercially available. At the conclusion of an operative abdom-nal procedure, 1000 mL of 4% icodextrin is left in the peritoneal cavityo separate loops of bowel while their injured serosal surfaces heal. Theolution remains in the peritoneal cavity for a few days and prevents theamaged serosal surfaces from coming in contact with each other. Theolution is marketed as Adept (Baxter Healthcare, Deerfield, IL) and has
een fairly thoroughly studied in both animals and humans.

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In both rabbits and rats, placing Adept in the peritoneal cavity in botheritonitis and wound healing models, postoperative adhesions wereeduced significantly.114,115 In a large multicenter, prospective, random-zed, double-blind study by Brown and colleagues, Adept was comparedith lactated Ringer’s solution in women undergoing laparoscopicynecologic surgery for adhesiolysis. At a second laparoscopy 4 to 8eeks later, the icodextrin solution was significantly more likely to

educe adhesions116 but was also associated with labial swelling in thexperimental group. In another randomized clinical study by DiZeregand colleagues, the incidence of adhesions was decreased from 52% to2% at a second laparoscopy.117 However, a meta-analysis of prospectiveandomized studies evaluating Adept was equivocal and could notecommend it for intra-abdominal adhesion prevention. It currently hasittle use in general surgery circles.118 Adept was recently approved byhe FDA primarily for use in reducing pelvic adhesions, which causenfertility.

olyethylene GlycolA commercially available preparation comprised of an old standardsed in bowel preps, polyethylene glycol, has been developed, whichnvolves spraying 2 precursors on the injured serosal or peritonealurfaces. The combined agents form a viscous gelatinous material, whichdheres to peritoneal surfaces and prevents serosal surfaces from comingnto contact. This preparation carries the name Spraygel (Confluenturgical, Waltham, MA) and is available in Germany and Australia.nimal studies have shown positive outcomes in reducing intraperitoneal

dhesions, and a few randomized studies have shown a reduction in pelvicdhesions from patients receiving Spraygel on closing the abdomen.119

owever, once again, a Cochrane meta-analysis failed to achieve statis-ical significance when Spraygel was used compared with the control.118

single component gel marketed as Adhibit (Angiotech Pharmaceuticals,ancouver, BC) has shown encouraging results in a randomized experi-ental trial involving patients undergoing myomectomy surgery.120

ibrin GluesSome anecdotal observations in operative fields in which fibrin gluesere utilized demonstrated a paucity of adhesions during reoperative

urgery. These preparations consist of fibrinogen and thrombin and, whenixed, produce tenaciously adherent gelatinous fibrin. Studies reveal thatbrin increases t-PA and PA-I by peritoneal cells121 and may impact
dhesion formation. However, experimental studies are conflicting and few

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ell-designed studies have been conducted to assess its efficacy.122-124

nother disadvantage of fibrin glue is an exorbitant expense, as well as anwkward application process.In summary, barrier products come the closest to an effective antiad-esion agent of any studied. Tables 15 and 16 summarize the current statef barrier agents in the United States.

ioactive PolypeptidesWork done by a Scandinavian group has produced a unique bioactiveeptide whose positively charged peptide (poly-L-lysine) adheres to thenjured peritoneum or serosa and then forms a matrix with negativelyharged poly-L-glutamate. Three experimental animal studies have dem-nstrated its ability to reduce adhesions without weakening the anasto-osis or affecting bleeding. The polycation has not been tested in

umans, and a more recent publication demonstrated a very narrowherapeutic window without toxicity.125 It is unlikely it will find any rolen preventing intra-abdominal adhesions.

nflammatory MediatorsExtensive research has been done looking at the role of inflammatoryediators in adhesion formation. Results suggest that several cytokines

nd growth factors play a role in regulating the genes that play a part innitiating adhesion formation probably by inhibiting fibrinolysis.126,127

ene products, such as TGF-�, ICAM-1, VCAM-1, and NK-1 are potentialandidates. Studies on TGF-� suggest that it contributes to reduced fibrino-ytic activity, and thus, may worsen adhesion formation.128,129 In one animaltudy, an antibody neutralizing TGF-� resulted in significant reduction in

ABLE 15. Preventing adhesions

FDA-approved barrier agents

Agent Company Composition Form Use Studies Comment

nterceed J&J Oxidized cellulose Sheet Adnexae Animal/human Ineffective inblood

eprafilm Genzyme Hyaluronatecarboxymethyl-cellulose

Sheet Peritoneum Animal/human Brittle

reclude Gortex PTFE Sheet Adnexae Animal/human Non-absorbepel Synthemed Glycolated

polymerGel Pericardium Animal/human Approved in

the UnitedStates

dept Baxter Icodextrin Liquid Peritoneum Animal/human Mixed results

DA, Food and Drug Administration; PTFE, polytetrafluoroethylene.

dhesions130 possibly through regulation of PAI-1.131


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Other studies suggest that IL-1 contributes to a decrease in fibrinolyticctivity possibly by releasing PAI-1.24 In a study conducted with rats,dministration of an anti-IL-1 agent resulted in the development ofignificantly fewer adhesions than in controls.132

A well-known neuropeptide substance P (SP) has recently been recog-ized as having some actions that might impact adhesion formation. SPas been detected in neurons found in adhesions and is a well-knownnflammatory mediator that works by altering the expression of ICAM-1,CAM-1, and TGF-�—all of which impact adhesion formation.133

eural endopeptidase is an enzyme that breaks down SP, and knock outice lacking this enzyme develop adhesions much more easily than

ontrols.134 Although it is unlikely that SP would ever be used therapeu-ically, further study is justified in an attempt to understand more fully the

echanisms of adhesion formation.Another intriguing agent that seems to inhibit adhesion formation is a

ubstance derived from the exoskeleton of crustaceans. NO-carboxym-

ABLE 16. Preventing adhesions

Barrier agents being studied (NOT FDA-Approved)

Agent Company Composition Form Use Studies Comment

ntergel Lifecore Ferrous hyaluronan Gel Peritoneum Animal/human

Allergic reactions:withdrawn frommarket

dcon P Gliatech Polyglycan esters Liquid Peritoneum Animal/human

FDA problems

logel Alliance Poloxamer Gel Peritoneum Animal/human

—

ncert Anika Modified hyal acid Gel Peritoneum Animal Used in spinalsurgery

ylans Inamed Hyaluronicmodification

Liquid Joints Animal Withdrawn from USmarket

aprolactone Solvay Cyclic lactone ester Liquid Peritoneum Animal Prevents tendonadhesions

yskon Medisan Dextran Liquid Peritoneum Animal/human

Mixed results

arbylan-SX CarbylanBiosurgery

Cross-linkedglycosamino-glycan

Gel Peritoneum Animal More effective thanSeprafilm inanimal studies

M 609 ScrippsClinic

Ab against alpha Vbeta 3 integrins

Liquid Vocal cord,Pericardium

Animal Unique mechanism

praygel (sprayshield)

Covidien Polyethylene glycol Liquid Peritoneum Animal/human

Appears to beeffective ingynecologicsurgery; used inEurope

dhibit Angiotech Fibrin-based Gel Peritoneum Animal/human

Effective ingynecologicsurgery; used inEurope

DA, Food and Drug Administration.

thylchitosan (NOCC) has been demonstrated to reduce adhesions in both


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at and rabbit studies.135,136 In a prospective randomized study involvingultiple centers, NOCC reduced both the extent and severity of pelvic

dhesions.137

Estrogen levels are also thought to have some impact on adhesionormation. Administration of gonadotropin releasing hormone (GnRH) orn estrogen antagonist, mifepristone, reduces postoperative adhesions inats and monkeys.138,139 Levels of t-PA and PA-I were measured in bothxperimental and control groups and were found to be diminished inhort-term follow-up, whereas PA-I was increased in long-term evalua-ions. However, studies in humans have revealed mixed results. In aandomized study evaluating patients after myomectomy, patients whoeceived GnRH were found to have no significant reduction in adhesions.140

owever, recent studies evaluating the impact of aromatase inhibitors andamoxifen on postoperative adhesions in rats were encouraging.141,142

Having excess levels of free radicals such as nitric oxide (NO) haveeen implicated as a mechanism of increased adhesion formation in aostoperative setting.143 NO simulated the production of cGMP andesulted in activation of protein kinase G. Reduction of phosphodiester-se-5 results in breakdown of cGMP, which leads to decreased collagenroduction and fibroblast apoptosis.144,145 An inhibitor of phosphodies-erase-5, sildenafil, has shown the capacity to reduce adhesions in animaltudies.146 Similarly, an inhibitor of NO synthase, methylene blue, decreasesostoperative adhesions in animals. Unfortunately, it also impairs anasto-otic healing.147

Reed and colleagues demonstrated elevated levels of mRNA for NK-1eceptor (NK-1R) and SP in early postoperative adhesions.133 Follow-upork showed that an antagonist to NK-1R after surgery significantly reduced

dhesions.148 In the same study, investigators gave the NK-1R antagonist andound that it lead to a significant increase in mRNA for t-PA.Recently, a study was conducted using a mini-osmotic pump in

valuating new agents for experimental pelvic adhesion reduction. Agentsncluded dipyridamole, lazaroids, trans-retinoic acid, and anti-inflamma-ory peptide-2.149 A potent thrombin inhibitor RecHirudin has also beenemonstrated to reduce peritoneal adhesions in 2 animal models.149

Other agents that have been studied and demonstrated varying levels ofdhesion inhibition include pentoxifylline,150 ACE inhibitors,151 angio-enesis inhibitors,152 some antibiotics,153 and chemotherapeutic agents,uch as 5-fluorouracil, and mitomycin C.154,155

Although much has been learned about adhesion inhibitors from theultitude of studies referenced previously in the text, there appears to be
need for thorough ongoing studies to further evaluate the mechanisms

oit

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f adhesion formation because no agent has yet been discovered thatnhibits adhesion formation without interfering with other healing func-ion.

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