Colonoscopy in the diagnosis of antibiotic-associated colitis. A prospective study.

Colonoscopic findings among 16 patients with histologically proved antibiotic-associated pseudomembranous colitis (PMC) were analyzed. The characteristic endoscopic changes of PMC with pseudomembranes were observed in only 5 (31%) out of 16 patients by sigmoidoscopy but in 11 (85%) out of 13 patients in whom colonoscopy was also performed. The findings suggest the importance of colonoscopy in the early diagnosis of PMC and indicate that the typical endoscopic changes of PMC are limited to the colon above the rectosigmoid area in most patients with antibiotic-associated colitis. It is emphasized that colonoscopy should be performed at least in clinically suspected PMC cases, in which the early diagnosis of PMC might be missed if sigmoidoscopy alone is performed.