RESEARCH Open AccessSigmoid diverticulitis:US findingsMaria Antonietta Mazzei1*,Nevada Cioffi Squitieri1,Susanna Guerrini1,Amato Antonio Stabile Ianora2,Lucio Cagini3,Luca Macarini4,Melchiore Giganti5,Luca Volterrani1AbstractAcute diverticulitis (AD) results from inflammation of a colonic diverticulum.It is the most common cause of acuteleft lower-quadrant pain in adults and represents a common reason for acute hospitalization,as it affects over halfof the population over 65 years with a prevalence that increases with age.Although 85% of colonic diverticulitiswill recover with a nonoperative treatment,some patients may have complications such as abscesses,fistulas,obstruction,and /or perforation at presentation.For these reasons,different classifications were introduced throughtimes to help clinicians to develop a correct diagnosis and guide the treatment and for the same reasons imagingis used in most cases both to realise a differential diagnosis and to guide the therapeutic management.US and CTare both usefull in diagnosis of diverticolitis,and their sensibility and specificity are similar.However CT scanning isessential for investigating complicated diverticular disease especially where there are diffuse signs and clinicalsuspicion of secondary peritonitis;instead in most uncomplicated cases the experienced sonographer may quicklyconfirm a diagnosis guided by the clinical signs.US is to be recommended in premenopausal women,and inyoung people to reduce dose exposure.BackgroundAcute diverticulitis (AD)results from inflammation of acolonicdiverticulum. Itisthemostcommoncauseofacuteleftlower-quadrantpaininadultsandrepresentsacommonreasonforacutehospitalization, asitaffectsoverhalfofthepopulationover65yearswithapreva-lencethat increaseswithage[1,2]. Although85%ofcolonicdiverticulitiswill recoverwithanonoperativetreatment, somepatientsmayhavecomplicationssuchasabscesses, fistulas, obstruction, and/or perforation atpresentation[3]. Moreoverclinicaldifferentiationfromothercausesof abdominopelvicpainisoftendifficult(Table1), soimagingisusedin mostcasesbothtorea-liseadifferentialdiagnosisandtoguidethetherapeuticmanagement[4]. HollerwegerAetalrealisedanalter-nativediagnosisin47outof175patientsclinicallysus-pectedof havingdiverticulitis, witharelativelyhighfrequency of epiploic appendagitis (8 out of 47 patients),ureterolitihasis (6 out of 47 patients), urinary tract infec-tionandpelvic inflammatory disease (4 out of 47patients), andother bowel pathologies, asischemiccolitis, infectiousenterocolitis andperforatedcarcinoma(3 out of 47 patients) [5]. Currently, Multidetector Com-puted tomography (MDCT) of the abdomen is often thediagnostictest of choice, especiallyin theurgentassess-mentofpatientswithAD, withsensitivity, specificity,andpositiveandnegativepredictivevalues all wellgreaterthan95%, allowingtheidentificationof bothcolonic abnormalities (particularlymural thickeninganddiverticula) and inflammatory changesin the pericolonicfat planes, gradingitsseverity, andidentifyingmostusual complications[6-8]. Theusual MDCTfeaturesincludesegmentalwallthickeningwithspasm, submu-cosal oedema, diverticula, vascularengorgement, andinflammatorychangesinthepericolicfat, plusfascial,mesenteric, and/orperitonealfluid[6]. Conventionalcontrast-enhancedMDCTis alsohighlyreliableinexcluding an underlying carcinoma [9,10]. Some Authorsclaims that CT sensitivityis higher than thatof ultra-sound (US) in detecting diverticulitis (81% versus 61%,p = 0.048) in unselected patients presenting with acuteabdominalpain, butthepositive predictivevalues arecomparable, whereas in presence of clinical suspicion ofdiverticulitis the sensitivity of USreaches the92%[11-15]. In particular US is highly sensitive and specificfor uncomplicated acute diverticulitis and for the primarycomplication of pericolic abscess [16-18]. In this review,* Correspondence:mariaantonietta.mazzei@unisi.it Contributed equally1Department of Medical,Surgical and Neuro Sciences,Section ofRadiologicalSciences.Siena,ItalyFull list of author information is available at the end of the articleMazzei et al. Critical Ultrasound Journal 2013, 5(Suppl 1):S5http://www.criticalultrasoundjournal.com/content/5/S1/S5 2013 Mazzei et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative CommonsAttributionLicense (http://creativecommons.org/licenses/by/2.0), whichpermitsunrestricted use,distribution, andreproductioninanymedium,provided theoriginal work is properly cited.we discuss the US findings of diverticulitis and the role ofUS in its diagnostic management.Main bodyPathogenesis and classificationsDiverticulitis results from occlusion of a colonic diverti-culum by stool, inflammation, or food particles, causing amicroperforation and surrounding pericolic inflamma-tion. A colonic diverticulum is a herniation of mucosaand submucosa, corresponding to aweak point wherethe vasa recti penetrate the tunica muscularis, so mostcolonic diverticula arefalse diverticula containing nomuscularis propria. In 1965 Painter et al. presented thehypothesis that diverticular disease was caused by excesspressureinthecolonduetosegmentationbasedoninsufficient intake of dietary fibre [19]. In the Westernworlddiverticulosisoccursprimarilyinthesigmoidcolon, corresponding to the highest intraluminal pres-sure, where they are often associated with other typicalfindings of diverticular disease (i.e. muscularis propriathickening, shortening and narrowing of the lumen). Theincidence for diverticulosis is 3366%, of these patients,1025% will develop an acute episode of diverticulitis [2].Otherriskfactorsare: obesity(BMI30), useofnon-steroidalanti-inflammatorydrugsoracetaminophen;smoking was not significantly associated with sympto-matic diverticular disease, and a genetic predispositionwas not proved yet [20]. Diverticula vary in size from tinyintramural andtransient phenomenatopermanentprotrusions uptoseveral centimeters indiameter.Retention of fecal matter within the diverticulum due toan occlusion may produce a mucosal abrasion resultingininfectionorinflammationofthediverticulumwall(diverticulitis). The process may realise a focal intramuralinflammatory mass or abscess, infiltrate along the bowelwalltoproduceaninflammatorybowelsegment, andperforate into sigmoid mesentery where the process isusually contained. Therefore its presentation may varygreatly per individual patient, from symptomatic diverti-culosistoperforateddiverticulitis[21-23], evenifthemajority of individuals with diverticulosis are asympto-matic [24-26]. However, perforation can cause intraperi-tonealcontaminationthatisassociatedwithamuchhigher morbidity and mortality. From 1978 until todaydifferent classifications were proposed for the staging ofacute complicated diverticolitis; first Hinchey that pro-posed a classification in 4 stages, developed to predictoutcomes following the surgical management of compli-cated diverticular disease (perforated disease) (stage I:mesocolic/pericolic abscess; stage II: pelvic abscess; stageIIIgeneralizedperitonitis; stageIVfaecalperitonitis)[27]. Then the much more detailed information providedby CT scans led earlier to modifications of the originalHinchey classification. Subcategories could be definedconsidering the radiological findings. In 1997 Sher et alintroducedthefirst modificationfordistinguishingbetween pericolic abscesses (stage I), distant abscessesamendableforpercutaneousdrainage(stageIIa), andcomplexabscessesassociatedwithapossiblefistula(stage IIb). This modification also implied the use of newtreatmentstrategiessuchasCT-guidedpercutaneousdrainageofabscesses(Table2)[28-30]. Fromthese,Table 1 Possible alternative diagnosis of Left Lower-Quadrant Pain.Gastrointestinal Genitourinary/gynecologic Vascular/OtherEpiploic appendagitis Ureterolithiasis Dissection/ruptured aneurysmIschemic colitis Urinary tract infection Abdominal wall abscessInfectious enterocolitis Ectopic pregnancy Abdominal wall hematomaPerforated carcinoma Hemorrhagic or rupture ovarian cyst Psoas abscessSmall bowel obstruction Ovarian torsion Retroperitoneal hemorrhageInflammatory bowel disease Ruptured corpus luteumAppendicitis Uterine fibroids torsionSmall bowel infarction Pelvic Inflammatory diseaseOmental infarctionIncarcerated herniaTable 2 Hinchey classification and modified Hinchey classification by Sher et al.Hinchey classification Modified Hinchey classification by Sher et alI pericolic abscess or phlegmon I pericolic abscessII pelvic,intrabdominal or retroperitoneal abscess IIa distant abscess amendable to percutaneous drainageIIb Complex absess associated with fistulaIII Generalized purulent peritonitis III Generalized purulent peritonitisIV Generalized fecal peritonitis IV Fecal peritonitisMazzei et al. Critical Ultrasound Journal 2013, 5(Suppl 1):S5http://www.criticalultrasoundjournal.com/content/5/S1/S5Page 2 of 7several other classifications have been made (Wasvary etal. in 1999, Kohler et al in 1999, Siewert et al in 1995),among that deserve mention the Hansen/Stock classifica-tionandKohleret alclassification, both basedon theclinicalseverityandpresentationofdisease(Table3)[31,32]. Finally in 2002 Ambrosetti et al. proposed a sim-plified staging of acute diverticulitis based on CT criteriaand showed its prognostic significance in a prospectivestudy: moderate diverticulitis defined by localized sig-moid wall thickening (1 hr),tenderness to palpation only in the left lower quadrant,and raised inflammatory markers; and are less likely tohavenauseaandvomiting[34]. Othersymptomsare:fever, absenceofperistalsis, anddefencemuscularis.Diverticular bleeding and pneumaturia (pathognomic for acolovesical fistula) are rare.The wide spectrum of diverticular disease requires a dif-ferentiated therapeutic approach to the different manifes-tations. Moderate cases of diverticular disease (phlegmonor small abscess) can be treated conservatively, generallywithantibiotics andaneasily digestible diet. Largeabscesses, ifamendableandusuallylargerthan5cm,should be good candidates for CT-guided percutaneousdrainage [35]. This procedure may relieve symptoms orfunction as a bridge to (elective) surgery. In cases of fecalperitonitisresultingfromaperforationacutesurgicalintervention should be warranted because it is associatedwith high morbidityand mortality(1035%) [36]. Itisnow thought that after a conservatively treated episode,diverticular disease usually follows a rather benign courseand that complications occur mostly at first presentation[37,38]. Therefore, elective sigmoid resections should berestricted for use in treating complicated disease, such assymptomatic stenosis, fistulas to a hollow organ, or recur-rent diverticular bleeding [39].ImagingImaging may not be necessary in patients with the classictriad of left lower-quadrant pain, fever, and leukocytosis,and in whom uncomplicated diverticulitis is suspected.Imaging also may not be necessary in patients with a his-tory of diverticulitis who present with relatively mild clini-cal symptoms of recurrent disease. However, consideringthe wide spectrum of diverticular disease , also dependingon the age of patients (clinical presentation may differ sig-nificantly in older patients where a reduction in symptomseverity causing a misdiagnosis could be present), and thepossibile difficult differential diagnosis from other causesof abdominopelvic pain, imaging often plays a definitiverole both to realise a differential diagnosis and to guidethe therapeutic management [1,8,40]. As reported above,today contrast-enhanced CT has a pivotal role in the clini-cal practice regarding diverticular disease, and because oftheirsuperiorsensitivityandspecificityupto100%,replaced the most important imaging modality [40]. Espe-cially when an associated abscess is suspected, a CT scancan be very helpful to demonstrate its presence, and alsofor evaluate the possibilityof apercutaneous drainage[41]. Inthecaseof diverticularbleeding, acontrast-enhanced CT examination may demonstrate a contrastblush; and even if it has to be considered that 80% of alldiverticular bleeding is self-limiting, occasionally successesofhighlyselectivearterialembolizationaredescribed.Although the role of interventional radiology is yet to bedetermined. Conventional contrast-enhanced MDCT isalso highly reliable in excluding other diagnoses of acuteabdomen and an underlying carcinoma (Figure 1)[14,15,42-44]. A colonoscopy is indicated when there isdoubt about cancer, persisting or recurrent complaints intheleftlowerquadrant, andsuspicion ofa stenosisorrecurrent blood loss. Follow-up colonoscopy for ruling outmalignancy is usually performed 6 weeks after an episodeof acute diverticulitis. Moreover the computedTable 3 Khler and Hansen/Stock classification.Khler Classification Hansen/Stock classificationSymptomatic uncomplicated disease 0 DiverticulosisRecurrent symptomatic disease I Acute uncomplicated diverticulitisComplicated disease: II Acute complicated diverticulitisHemorrhage,Abscess,Phlegmon a.Phlegmon,peridiverticulitisFistula,Perforation,Stricture b.Abscess,sealed perforationPurulent and fecal peritonitis,Small bowel c.Free perforationobstruction due to post-inflammatory adhesions III Chronic recurrent diverticulitisMazzei et al. Critical Ultrasound Journal 2013, 5(Suppl 1):S5http://www.criticalultrasoundjournal.com/content/5/S1/S5Page 3 of 7tomography colonography (CTC) seems to be a reasonablealternativeinfollow-upofpatientswithsymptomaticdiverticular disease [45]. In recent years, magnetic reso-nance imaging (MRI) has gained popularity, because itlacks the ionizing radiation and even if CT remains themodality of choice; however MRI can similarly demon-strate findings of diverticulitis and could be useful in diag-nosis of ischemic colitis [46,47]. Although, colonicdiverticulitis is easily diagnosed and classified (graded) byCT than by ultrasound (US), it is important to be aware ofthe US signs of diverticulitis considering that US is oftenused as a first modality in the diagnostic approach to theacute abdomen.US: techinique and findingsUS is an imaging modality widely available in the Emer-gency Department. The lower cost and in particular thelack of radiation exposure are the most important advan-tages of US compared to CT. Furthermore US is a real-time dynamic examination and this characteristic conveysdynamic information about bowel motility and changes inposition, and to depictblood flow. Another importantadvantage of US examination is the possibility to correlatetheUS findings with the point of maximaltenderness.Besides, in not too obese patients, US may be superior toCT, and it is most useful in early, uncomplicated diverticu-litis. From a technical point of view , both curved (3.55.0-MHz) and linear (5.0 12.0-MHz) transducers are mostcommonly used, in particular the higher frequency probesare useful for detailed investigation of the large bowel wall,identifying its typical haustral pattern. Focal bowel masses,segments of wall thickening, and dilated loops may be evi-dent even at lower frequencies, but high-frequency probesare essential to identify and chracterize changes in thelayers of the bowel wall. At higher frequencies, US imagesthe bowel wall as five alternating bands (gut signature) ofhighandlowechogenicitytoproduceacharacteristicsonographic signature approximating to the concentriclayered histologic structure [48]. Visualization of the fineinner and outer bright layers (interface echoes) is highlydependent on the echogenicity of adjacent structures andis most easily seen where there is fluid in the bowel lumenor ascites between bowel loops. Even at lower diagnosticfrequencies in loops further from the probe, at least thetwo most prominent layers are evident due to their relativethickness and high contrast: the bright submucosa (thirdlayer) and the dark muscularis propria (fourth layer) [34].Doppler scanning demonstrates no signal in normal bowelwall [49,50].Athinneddiverticularwallmaybedemonstratedathigher probe frequencies with a reduced gut signature dueto the absence of muscularis propria. Diverticula appear asbright ears out of the bowel wall with acoustic shadow-ing due to the presence of gas or inspissated feces; further-more the neck of diverticulum may be identified as anechogenic band traversing hypoechoic muscularis propriathat is often thickened. The diagnostic criteria for diverti-culitis that has been used in US and CT are the same: 1)at least one diverticulum, 2) signs of inflammation of peri-odic fat (dirty fat/stranding) and 3) thickened bowel wall >4-5 mm [33]. An isolated inflamed diverticulum is identi-fied as an enlarged echo-poor protrusion from the colonwall, with an ill-defined margin surrounded by echogenicnoncompressiblefat, whichrepresents theinflamedmesentery and omentumsealing off the imminent per-foration. The diverticulum wall signature is lost. A centralshadowing echogenicity may indicate the presence of feca-lith(Figure2)[51]. OftentheinflammationwillhaveFigure 1 Contrast-enhanced MDCT 2D reconstruction on axial oblique (a) and coronaloblique (b) planes shows a neoplastic thickening of thecolonic wall (sigmoid tract) in presence of diverticulitisis.Mazzei et al. Critical Ultrasound Journal 2013, 5(Suppl 1):S5http://www.criticalultrasoundjournal.com/content/5/S1/S5Page 4 of 7Figure 2Sonographicfeatures ofuncomplicated diverticulitis: diverticulaappearas brightearoutof thebowel wall (a); acentral shadowingechogenicity may indicate the presence of fecalith (b).Figure3Sonographicfeaturesofcomplicateddiverticulitis: theimagesshowthepresenceof diveticula, thickeningofthebowel wall andpericolic fluid (a,b)Mazzei et al. Critical Ultrasound Journal 2013, 5(Suppl 1):S5http://www.criticalultrasoundjournal.com/content/5/S1/S5Page 5 of 7extended into the bowel producing asymmetrical or cir-cumferential hypoechoicmural thickeningthat maydemonstrate hyperemia on Doppler scanning. Diverticuli-tis may progress to an intramural or pericolic abscess indi-cated by an anechoic collection that may contain pocketsof air or debris (Figure 3) [4]. Right-sided colonic diverti-culitis in many respects differs from its left-sided cousin.Diverticula of the right colon are usually congenital, soli-tary, true diverticula containing all bowel wall layers. Thefecoliths within these diverticula are larger and the diverti-cular neck is wider. There is no hypertrophy of the muscu-laris of the right colonic wall . Puylaert JB in a study of 110patientswithrightcolonicdiverticulitisclearlyshow,throughUSandCT, thatitinvariablyhasafavorablecourse andnever leads tofree perforationor largeabscesses. Although relatively rare (left:right = 15:1), it iscrucial to make a correct diagnosis since the clinical symp-toms of acute right lower quadrant pain may lead to anunnecessary appendectomy or even right hemicolectomy.ConclusionsUS and CT are both useful in diagnosis of diverticolitis,and their sensibility and specificity are similar. However,CT may be more likely to identify alternative causes ofabdominal pain and it is essential for investigating compli-cated diverticular disease especially where there are diffusesigns and clinical suspicion of secondary peritonitis. [52]Instead in most uncomplicated cases the experienced sono-grapher may quickly confirm a diagnosis guided by theclinical signs. US is to be recommended in premenopausalwomen, and in young people to reduce dose exposure.Competing interestsThe authors declare that they have no competing interests.AcknowledgementsWe thank Ms Julia Hassall for reviewing the english and Dr.Palmino Saccofor helping in the preparation of the images.DeclarationsThis article has been published as part of CriticalUltrasound Journal Volume5 Supplement 1,2013:Topics in emergency abdominal ultrasonography.Thefull contents of the supplement are available online at http://www.criticalultrasoundjournal.com/supplements/5/S1.Publication of thissupplement has been funded by the University of Molise,University ofSiena,University of Cagliari,University of Ferrara and University of Turin.Author details1Department of Medical,Surgical and Neuro Sciences,Section ofRadiologicalSciences.Siena,Italy.2University of Bari,Diagnostic ImagingSection,Bari,Italy.3University of Perugia,Thoracic Surgery Unit,Perugia,Italy.4University of Foggia,Department of Radiology,Foggia,Italy.5University ofFerrara,Dipartimento di Scienze Chirurgiche,Ferrara,Italy.Published:15 July 2013References1. 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