Colonic diverticulitis: diagnostic value and appearance of inflamed diverticula-sonographic evaluation

Acute bowel inflammation frequently originates from thin-walled diverticula of the colon. Not the presence of diverticula, but the demonstration of an inflamed diverticulum, is diagnostic of diverticulitis in cases of bowel wall thickening and pericolic inflammation. The aim of this study was to investigate the sonographic appearance and detectability of inflamed diverticula. One hundred seventy-five consecutive patients with clinically suspected diverticulitis under-went sonographic examination. Outpouchings from the colonic wall centred in the pericolic inflammation were considered inflamed diverticula. Depending on the sonographic appearance they were divided into four groups: hypoechoic; predominantly hyperechoic; hyperechoic with surrounding hypoechoic rim; and hyperechoic with acoustic shadowing. Sonography showed inflamed diverticula in 79 (77%) of 102 patients with diverticulitis. Inflamed diverticula were hypoechoic in 37%, predominantly hyperechoic in 4%, hyperechoic with surrounding hypoechoic rim in 41% and hyperechoic with acoustic shadowing in 18% of patients. In 23 (23%) of 102 patients no inflamed diverticulum was demonstrable. This group included 17 patients with complicated diverticulitis and 6 false-negative cases. An inflamed diverticulum as a sign of diverticulitis yielded an overall sensitivity of 77% and a specificity of 99%. Sensitivity in uncomplicated disease was 96%. In patients with uncomplicated diverticulitis an inflamed diverticulum is a sign of diverticulitis with excellent sensitivity and specificity, usually with solitary and less frequently with more than one inflamed diverticulum being demonstrable. In patients with complicated diverticulitis an inflamed diverticulum is often not detectable.