Teaching Case

50-year-old man with a four day left lower quadrant pain. Laboratory parameters revealed mild inflammation.

A 50-year-old man was admitted to the surgical department due to left lower quadrant pain of 4 days duration and mild diarrhea. White blood cell count was within the normal range. The erythrocyte sedimentation rate was slightly elevated. Physical examination revealed tenderness in the left lower quadrant. A transabdominal sonogram was performed.

Acute colonic diverticulitis is a predominantly extramucosal inflammatory process. Diverticulitis primarily results from obstruction of the orifice of a diverticulum, leading to localized inflammation and to a microperforation in almost all cases. Subsequently, peridiverticular inflammation, a pericolic abscess, and less commonly a fistula to a nearby organ or generalized peritonitis may occur. Barium enema and colonoscopy have an inherent limitation in the evaluation of the full extent of diverticulitis which is primarily an extraluminal disease. Therefore, cross sectional imaging modalities like sonography or CT are the imaging methods of choice for the diagnosis of diverticulitis, as well as for the determination of alternative diagnoses. Various studies have shown that sonography can adequately diagnose diverticulitis [1-5]. The following 3 sonographic findings are indicative of diverticulitis: segmental bowel wall thickening (5 mm or more); pericolic inflammation (increased echogenicity of pericolic fat and loss of compressibility); inflamed diverticula (outpouchings from the colonic wall centred in the pericolic inflammation) or evidence of complicated disease (perforations, abscesses, fistulas). Inflamed diverticula are centred in the pericolic inflammation and can display variable echogenicity from hypoechoic to hyperechoic. Limitations leading to false-negative transabdominal sonographic results arise primarily in obese patients and when the lower sigmoid colon is affected. Transrectal or endovaginal sonography are other imaging modalities available for assessment of the lower sigmoid colon [5]. The major reason for false-positive sonograms is the nonspecificity of colonic mural thickening which may also occur in Crohn’s disease, ulcerative colitis, ischemic colitis, infectious ileocolitis, carcinoma, and lymphoma [3]. Other false-positive sonograms can result from pericolonic abscesses from perforated appendicitis or perforated colonic carcinoma. If all three above mentioned criteria are applied, sonography can diagnose uncomplicated diverticulitis with high sensitivity and specificity. In complicated cases CT should be performed in addition to sonography for an exact staging of the inflammatory process.