Colonoscopy for unexplained rectal bleeding.

Two hundred and thirty-nine patients underwent colonoscopy for unexplained rectal bleeding. Local anorectal conditions were excluded by digital and proctosigmoidoscopic examinations and results of barium studies were negative for all patients. A cause for bleeding was found in 95 patients. Thirty-nine had adenomatous polyps, 24 had unrecognised inflammatory bowel disease, and most importantly 23 (10% of series) had carcinomas. Forty patients had diverticular disease, but nine of them were found to have an adenomatous polyp and four a carcinoma. Colonoscopy can contribute positively to the investigation and treatment of unexplained rectal bleeding and may prevent unnecessary laparotomy.