- Known or suspected organic disorders of the large bowel (i.e., obstruction, carcinoma, or inflammatory bowel disease). Results of a barium enema with flexible sigmoidoscopy or of a colonoscopic examination performed within the last 12 months were needed to rule out organic disorders. An examination performed within the last 3 years was acceptable, if the examination had been performed for an evaluation of constipation, if there was no history or evidence of weight loss, anemia, or rectal bleeding, and if the subject had had three consecutively negative stool occult blood tests at screening. Subjects with polyps discovered by colonoscopy that were untreated (i.e., by polypectomy) were to be excluded;