Appendicitis A common disease in mexican emergencies. Diagnosis, treatment and complications. Castro Castillo, A. Gutiérrez Gutiérrez, B., Michán Rodríguez, E. 04/02/2009

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List of Contents

Introduction 3

Signs 9

Laboratory Findings 11

Imaging Studies 12

Diagnosis and Differential Diagnosis 15

Complications 18

Prevention 24

Treatment 25

Conclusion 26

References 29

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ACUTE APPENDICITIS

Incidence and Epidemiology

With more than 250,000 appendectomies performed annually, appendicitis is the most common abdominal surgical emergency in the United States. The peak incidence of acute appendicitis is in the second and third decades of life; it is relatively rare at the extremes of age. However, perforation is more common in infancy and in the elderly, during which periods mortality rates are highest. Males and females are equally affected, except between puberty and age 25, when males predominate in a 3:2 ratio. The incidence of appendicitis has remained stable in the United States over the last 30 years, while the incidence of appendicitis is much lower in underdeveloped countries, especially parts of Africa, and in lower socioeconomic groups. The mortality rate in the United States decreased eightfold between 1941 and 1970 but has remained at <1 per 100,000 since then.

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Pathogenesis

Appendicitis is believed to occur as a result of appendiceal luminal obstruction. Obstruction is most commonly caused by a fecalith, which results from accumulation and inspissation of fecal matter around vegetable fibers. Enlarged lymphoid follicles associated with viral infections (e.g., measles), inspissated barium, worms (e.g., pinworms, Ascaris, and Taenia), and tumors (e.g., carcinoid or carcinoma) may also obstruct the lumen. Other common pathological findings include appendiceal ulceration. The cause of the

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ulceration is unknown, although a viral etiology has been postulated. Infection with Yersinia organisms may cause the disease, since high complement fixation antibody titers have been found in up to 30% of cases of proven appendicitis. Luminal bacteria multiply and invade the appendiceal wall as venous engorgement and subsequent arterial compromise result from the high intraluminal pressures. Finally, gangrene and perforation occur. If the process evolves slowly, adjacent organs such as the terminal ileum, cecum, and omentum may wall off the appendiceal area so that a localized abscess will develop, whereas rapid progression of vascular impairment may cause perforation with free access to the peritoneal cavity. Subsequent rupture of primary appendiceal abscesses may produce fistulas between the appendix and bladder, small intestine, sigmoid, or cecum. Occasionally, acute appendicitis may be the first manifestation of Crohn's disease.

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While chronic infection of the appendix with tuberculosis, amebiasis, and actinomycosis may occur, a useful clinical aphorism states that chronic appendiceal inflammation is not usually the cause of prolonged abdominal pain of weeks' or months' duration. In contrast, recurrent acute appendicitis does occur, often with complete resolution of inflammation and symptoms between attacks. Recurrent acute appendicitis may also occur if a long appendiceal stump is left after initial appendectomy.

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Clinical Manifestations

The sequence of abdominal discomfort and anorexia associated with acute appendicitis is pathognomonic. The pain is described as being located in the periumbilical region initially and then migrating to the right lower quadrant. This classic sequence of symptoms occurs in only 66% of patients.

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However, in a male patient these symptoms are sufficient to advise surgical exploration. The differential diagnoses for periumbilical and right lower quadrant pain is listed in Table 294-1. The periumbilical abdominal pain is of the visceral type, resulting from distention of the appendiceal lumen. This pain is carried on slow-conducting C fibers and is usually poorly localized in the periumbilical or epigastric region. In general, this visceral pain is mild, often cramping and usually lasting 4–6 h, but it may not be noted by stoic individuals. As inflammation spreads to the parietal peritoneal surfaces, the pain becomes somatic, steady, and more severe and aggravated by motion or cough. Parietal afferent nerves are A delta fibers, which are fast-conducting and unilateral. These fibers localize the pain to the right lower quadrant. Anorexia is very common; a hungry patient does not have acute appendicitis. Nausea and vomiting occur in 50–60% of cases, but vomiting is usually self-limited. Change in bowel habit is of little diagnostic value, since any or no alteration may be observed, although the presence of diarrhea caused by an inflamed appendix in juxtaposition to the sigmoid may cause diagnostic difficulties.

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Urinary frequency and dysuria occur if the appendix lies adjacent to the bladder.

SIGNS

Physical findings are determined principally by the anatomic position of the inflamed appendix, as well as by whether the organ has already ruptured when the patient is first examined.

Vital signs are minimally changed by uncomplicated appendicitis. Temperature elevation is rarely more than 1°C (1.8°F) and the pulse rate is normal or slightly elevated. Changes of greater magnitude usually indicate that a complication has occurred or that another diagnosis should be considered.

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Patients with appendicitis usually prefer to lie supine, with the thighs, particularly the right thigh, drawn up, because any motion increases pain. If asked to move, they do so slowly and with caution.

The classic right lower quadrant physical signs are present when the inflamed appendix lies in the anterior position. Tenderness is often maximal at or near McBurney's point.

8 Direct

rebound tenderness is usually present. Additionally, referred or indirect rebound tenderness is present. This referred tenderness is

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felt maximally in the right lower quadrant, indicating localized peritoneal irritation.

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Rovsing's sign—pain in the right lower quadrant when palpatory pressure is exerted in the left lower quadrant—also indicates the site of peritoneal irritation. Cutaneous hyperesthesia in the area supplied by the spinal nerves on the right at T10, T11, and T12 frequently accompanies acute appendicitis. In patients with obvious appendicitis, this sign is superfluous, but in some early cases, it may be the first positive sign. Hyperesthesia is elicited either by needle prick or by gently picking up the skin between the forefinger and thumb.

Muscular resistance to palpation of the abdominal wall roughly parallels the severity of the inflammatory process. Early in the disease, resistance, if present, consists mainly of voluntary guarding. As peritoneal irritation progresses, muscle spasm increases and becomes largely involuntary, i.e., true reflex rigidity due to contraction of muscles directly beneath the inflamed parietal peritoneum.

Anatomic variations in the position of the inflamed appendix lead to deviations in the usual physical findings. With a retrocecal appendix, the anterior abdominal findings are less striking and

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tenderness may be most marked in the flank. When the inflamed appendix hangs into the pelvis, abdominal findings may be entirely absent, and the diagnosis may be missed unless the rectum is examined. As the examining finger exerts pressure on the peritoneum of the cul-de-sac of Douglas, pain is felt in the suprapubic area, as well as locally within the rectum. Signs of localized muscle irritation may also be present. The psoas sign indicates an irritative focus in proximity to that muscle. The test is performed by having patients lay on their left side as the examiner slowly extends the right thigh, thus stretching the iliopsoas muscle. The test is positive if extension produces pain. Similarly, a positive obturator sign of hypogastric pain on stretching the obturator internus indicates irritation in the pelvis. The test is performed by passive internal rotation of the flexed right thigh with the patient supine.

LABORATORY FINDINGS

Mild leukocytosis, ranging from 10,000 to 18,000/mm

3, is usually present in patients with

acute, uncomplicated appendicitis and is often accompanied by a moderate polymorphonuclear predominance. However, white blood cell counts are variable. It is unusual for the white blood cell

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count to be greater than 18,000/mm3 in

uncomplicated appendicitis. White blood cell counts above this level raise the possibility of a perforated appendix with or without an abscess. Urinalysis can be useful to rule out the urinary tract as the source of infection. Although several white or red blood cells can be present from ureteral or bladder irritation as a result of an inflamed appendix, bacteriuria in a catheterized urine specimen is not generally seen with acute appendicitis.

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Imaging Studies

Plain films of the abdomen, although frequently obtained as part of the general evaluation of a patient with an acute abdomen, are rarely helpful in diagnosing acute appendicitis. However, plain radiographs can be of significant benefit in ruling out other pathology. In patients with acute appendicitis, one often sees an abnormal bowel gas pattern, which is a nonspecific finding. The presence of a fecalith is rarely noted on plain films, but if present, is highly suggestive of the diagnosis. A chest x-ray is sometimes indicated to rule out referred pain from a right lower lobe pneumonic process.

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Additional radiographic techniques include barium enema and radioactive-labeled leukocyte scans. If the appendix fills on barium enema, appendicitis is excluded.

On the other hand, if the appendix does not fill, no determination can be made. To date, there has not been enough experience with radionuclide scans to assess their utility.

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Graded compression sonography has been suggested as an accurate way to establish the diagnosis of appendicitis. The technique is

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inexpensive, can be performed rapidly, does not require contrast, and can be used even in pregnant patients. Sonographically, the appendix is identified as a blind-ending, nonperistaltic bowel loop originating from the cecum. With maximal compression, the diameter of the appendix is measured in the anteroposterior dimension. A scan is considered positive if a noncompressible appendix 6 mm or greater in the anteroposterior direction is demonstrated (Fig. 29-3). The presence of an appendicolith establishes the diagnosis. The presence of thickening of the appendiceal wall and periappendiceal fluid is highly suggestive. Sonographic demonstration of a normal appendix, which is an easily compressible blind-ending tubular structure measuring 5 mm or less in diameter, excludes the diagnosis of acute appendicitis. The study is considered inconclusive if the appendix is not visualized and there is no pericecal fluid or mass. When the diagnosis of acute appendicitis is excluded by sonography, a brief survey of the remainder of the abdominal cavity should be performed to establish an alternative diagnosis. In females of child-bearing age, the pelvic organs must be adequately visualized either by transabdominal or endovaginal ultrasonography in order to exclude

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gynecologic pathology as a cause of acute abdominal pain. The sonographic diagnosis of acute appendicitis has a reported sensitivity of 55 to 96% and a specificity of 85 to 98%.

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Sonography is similarly effective in children and pregnant women, although its application is somewhat limited in late pregnancy.

Diagnosis & Differential Diagnosis

The clinical diagnosis of appendicitis rests on a combination of localized pain and tenderness accompanied by signs of inflammation, such as fever, leukocytosis, and elevated C-reactive protein levels. Migration of pain from the periumbilical area to the right lower quadrant is

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also diagnostically significant. In the absence of signs of inflammation, the diagnosis is less certain (ie, falsely positive), and in this situation a CT scan might be of value.

The best strategy in equivocal cases is to observe the patient for a period of 6 hours or more. During this time, patients with appendicitis experience increasing pain and signs of inflammation and those without appendicitis generally improve. False-positive diagnoses often involve cases where the surgeon has accorded more significance to the patient's pain than to the presence or absence of inflammatory signs. Anorexia, nausea, and rectal tenderness are not indicative of appendicitis. During the past 15 years, the overall false-positive rate for the

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diagnosis of appendicitis has dropped from 15% to 10% without an accompanying rise in the number of perforations. Thus, diagnostic accuracy appears to be improving.

The diagnosis of acute appendicitis is particularly difficult in the very young and in the elderly. These are the groups where diagnosis is most often delayed and perforation most common. Infants manifest only lethargy, irritability, and anorexia in the early stages, but vomiting, fever, and pain are apparent as the disease progresses. Classic symptoms may not be elicited in aged patients, and the diagnosis is often not considered by the examining physician. The course of appendicitis is more virulent in the elderly, and suppurative complications occur earlier.

The highest incidence of false-positive diagnosis (20%) is in women between ages 20 and 40 and is attributable to pelvic inflammatory disease and other gynecologic conditions. Compared with appendicitis, pelvic inflammatory disease is more often associated with bilateral lower quadrant tenderness, left adnexal tenderness, onset of illness within 5 days of the last menstrual period, and a history that does not include nausea and

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vomiting. Cervical motion tenderness is common in both diseases.

Complications

The complications of acute appendicitis include perforation, peritonitis, abscess, and pylephlebitis.

PERFORATION

Delay in seeking medical care appears to be the principal reason for perforations; the disease has just been allowed to progress according to its natural history.

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Perforation is accompanied by more severe pain and higher fever (average, 38.3 °C) than in appendicitis. It is unusual for the acutely inflamed appendix to perforate within the first 12 hours. The appendicitis has progressed to perforation by the time of appendectomy in about 50% of patients under age 10 or over age 50. Nearly all deaths occur in the latter group.

The acute consequences of perforation vary from generalized peritonitis to formation of a tiny abscess that may not appreciably alter the symptoms and signs of appendicitis. Perforation in young women increases the subsequent risk of tubal infertility about fourfold.

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PERITONITIS

Localized peritonitis results from microscopic perforation of a gangrenous appendix, while spreading or generalized peritonitis usually implies gross perforation into the free peritoneal cavity. Increasing tenderness and rigidity, abdominal distention, and adynamic ileus are obvious in patients with peritonitis. High fever and severe toxicity mark progression of this catastrophic illness in untreated patients.

APPENDICEAL ABSCESS (APPENDICEAL MASS)

Localized perforation occurs when the periappendiceal infection becomes walled off by omentum and adjacent viscera. The clinical presentation consists of the usual findings in appendicitis plus a right lower quadrant mass. An ultrasound or CT scan should be performed; if an abscess is found, it is best treated by percutaneous ultrasound-guided aspiration. Opinion differs about how small abscesses and phlegmons should be handled.

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Some surgeons prefer a regimen consisting of antibiotics and expectant management followed by elective appendectomy 6 weeks later. The purpose is to avoid spreading the localized infection, which usually resolves in response to the antibiotics. Other surgeons recommend immediate appendectomy, which some believe shortens the duration of the illness. However, the immediate surgery approach has significant complications in a higher percentage of patients. There is not currently a consensus.

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When the surgeon encounters an unsuspected abscess during appendectomy, it is usually best to proceed and remove the appendix. If the abscess is large and further dissection would be hazardous, drainage alone is appropriate.

Appendicitis recurs in only 10% of patients whose initial treatment consisted of antibiotics or antibiotics plus drainage of an abscess. Therefore, when the presence of ancillary conditions increases the risks of surgery, interval appendectomy may be postponed unless symptoms recur.

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PYLEPHLEBITIS

Pylephlebitis is suppurative thrombophlebitis of the portal venous system. Chills, high fever, low-grade jaundice, and, later, hepatic abscesses are the hallmarks of this grave condition. The appearance of shaking chills in a patient with acute appendicitis demands vigorous antibiotic therapy to prevent the development of pylephlebitis.

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CT scanning is the best means of detecting thrombosis and gas in the portal vein. In addition to antibiotics, prompt surgery is indicated to treat appendicitis or other primary sources of infection (eg, diverticulitis).

Prevention

In the past it was common to perform an incidental appendectomy in people under age 50 during the course of an abdominal operation for another illness—as long as the exposure was adequate and there were no specific contraindications. The declining lifetime risk of appendicitis now calls this practice into question. A related question concerns the appropriate course when a laparoscopy is performed for presumptive appendicitis and the appendix looks normal. The trend in this case is to leave the appendix intact—not to remove it prophylactically or on the assumption that the visual assessment may be inaccurate.

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Treatment

Treatment consists of surgical removal of the inflamed appendix using either laparotomy or laparoscopic-assisted technique. Laparotomy is faster, simpler, and less-expensive, with a lower rate of complications, but laparoscopy allows visualization of other possible causes. Recent advances in surgical technology have shown other benefits of laparoscopic procedures: faster recovery, shorter hospital stay, and decreased postoperative pain.

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Conclusion

While there is a statistically significant relationship between total WBC count and acute appendicitis in ED pediatric and adult patients with signs and symptoms suggestive of acute appendicitis, this relationship is modest and probably not clinically useful save expediting disposition with consultants who may expect it and cause delays in evaluation and treatment

2.

Body temperature is an even worse discriminator for patients with appendicitis than the total WBC count. Statistically, the presence of fever makes the patient no more or less likely to have appendicitis

2. However, this study by Wang et

al1, suggests that in an exclusively pediatric

population, WBC count and differential might be useful in the diagnosis of appendicitis in pediatric patients presenting to the ED with acute non traumatic abdominal pain.

There were several notable limitations to this study. Of significance, only 57% of patients enrolled actually got a white cell count. One can speculate a selection bias toward laboratory investigations in more ill-appearing patients or those with more ambiguous histories and physical examinations. A bias such as this could easily and falsely increase the specificity of the

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WBC count and artificially lower the negative predictive value. The take home lesson is that until there are better-defined parameters for laboratory testing, a low or normal white count should not be considered reassuring when clinical suspicion for acute appendicitis is high and the high WBC count for age may appropriately increase suspicion of appendicitis—although the upper and lower limits of these counts and differentials remains unclear.

Laboratory results (and the literature supporting their use!) should always be used in conjunction with a thorough history, physical examination and surgical consultation in the setting of suspected acute appendicitis. Despite the long history of surgical treatment of acute appendicitis, knowledge of the ideal combination of imaging and laboratory testing remains surprisingly scant.

3-11 This leads us to ask several questions

which we will examine in subsequent article reviews on this important topic:

1. Does the laboratory evaluation have an effect on the utilization of radiologic evaluation of suspected appendicitis?

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2. Do additional laboratory/radiological evaluation of the patient with suspected appendicitis cause delays in surgical intervention and do these evaluations have any significant morbidity, mortality or significant effect on the negative appendectomy rate?

3. How much do evaluation and testing beyond the physical examination cost the patients, third-party payers?

Apart from the history and physical examination, are there any emerging diagnostic modalities that can simplify and improve the accuracy of the diagnosis of acute appendicitis?

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List of References

1-. Gearhart Susan L, Silen William, "Chapter

294. Acute Appendicitis and Peritonitis"

(Chapter). Fauci AS, Braunwald E, Kasper DL,

Hauser SL, Longo DL, Jameson JL, Loscalzo J:

Harrison's Principles of Internal Medicine, 17th

Edition:

http://www.accessmedicine.com/content.aspx?aI

D=2881699.

2-.Jaffe Bernard M, Berger David H, "The

Appendix" (Chapter). Brunicardi FC, Andersen

DK, Billiar TR, Dunn DL, Hunter JG, Matthews

JB, Pollock RE, Schwartz SI: Schwartz's

Principles of Surgery, 8th Edition:

http://www.accessmedicine.com/content.aspx?aI

D=810876

3-.Way Lawrence W, "Chapter 28. Appendix"

(Chapter). Doherty GM, Way LW: CURRENT

Surgical Diagnosis and Treatment, 12th Edition:

http://www.accessmedicine.com/content.aspx?aI

D=2061629

4-. Barter Cindy, Dunne Laura, "Chapter 29.

Abdominal Pain" (Chapter). South-Paul JE,

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Matheny SC, Lewis EL: CURRENT Diagnosis &

Treatment in Family Medicine, 2nd Edition:

http://www.accessmedicine.com/content.aspx?aI

D=3035566

5-. Birkhahn, R. H.; Briggs, M.; Datillo, P. A.; Van

Deusen, S. K.; Gaeta, T. J., Classifying patients

suspected of appendicitis with regard to

likelihood. Am J Surg 2006, 191, (4), 497-502.