Toxic megacolon: role of CT in evaluation and detection of complications

The purpose of this study is to determine the role of CT in the evaluation and in detecting complications in patients with toxic megacolon. A retrospective analysis of CT findings of 18 consecutive patients with toxic megacolon was performed. Underlying etiology included 12 patients with pseudomembranous colitis (PC), four patients with ulcerative colitis and two patients with cytomegalovirus colitis. Eleven patients were HIV+. CT features, correlation with severity of disease and development of complications were analyzed. Colonic dilatation with intraluminal air and/or fluid with a distorted colonic contour or an ahaustral pattern was seen in all patients. In four patients (22%), CT depicted complications-two colonic perforations and two septic thrombosis of the portal system. Six patients died (33%), three of whom had the above complications. The presence and degree of submucosal edema (accordion sign, target sign), wall thickening, degree of dilatation, nodular contour and ascites did not correlate with clinical outcome. Two thirds of patients with toxic megacolon had PC as the underlying etiology. CT was helpful in depicting diffuse colitis, and it was instrumental in detecting life-threatening abdominal complications, contributing to the management of these patients. CT abnormalities cannot be used to predict the clinical outcome unless complications develop.