Pseudomembranous colitis with rectosigmoid sparing on barium studies.

The classic description of pseudomembranous colitis on barium enema studies is that of pancolitis with thickened haustral folds, a shaggy luminal contour, and/or mucosal plaques. However, the authors describe six patients with proved pseudomembranous colitis in whom barium studies (four double-contrast barium enema studies, one single-contrast barium enema study, and one peroral pneumocolon study) demonstrated rectosigmoid sparing with proximal colitis extending from the cecum to the sigmoid colon (three cases) or to the descending colon (three cases). In all six cases, endoscopy revealed a normal rectum or mild, nonspecific proctosigmoiditis without evidence of pseudomembranes in the rectosigmoid colon. Four patients had an atypical clinical presentation with bloody diarrhea (three cases) or minimal mucous diarrhea (one case). Thus, the diagnosis of pseudomembranous colitis may initially be suggested on barium studies in patients who have relative sparing of the rectosigmoid colon with characteristic findings more proximally in the colon.