Colonoscopic evaluation of rectal bleeding: a study of 304 patients.

We studied 258 patients with rectal bleeding and 46 patients with anemia and occult blood in the stool. All 304 patients had negative proctosigmoidoscopies, single-contrast barium studies that were negative or showed diverticula only, and colonoscopic evaluation. In the 258 patients, the overall incidence of finding significant lesions by colonoscopy was 41.5%. Twenty-nine patients (11.2%) had carcinoma and 17 patients (6.6%) had cecal telangiectasia. In the 46 patients, the overall incidence of finding significant lesions was 19.6%. Three patients with carcinoma were found in this group. A significant number of both benign and malignant lesions were detected by colonoscopy proximal to the splenic flexure. Colonoscopy should be done in patients with rectal bleeding or anemia and occult blood in the stool who have had negative proctosigmoidoscopies and single-contrast barium studies interpreted as normal or showing diverticula.