Your physician may recommend colonoscopy because of unexplained rectal bleeding, unexplained pain or to evaluate a condition, such as inflammatory bowel disease. Your doctor may also want an evaluation to rule out colon cancer because you or a close relative have a history of colon polyps. This outpatient procedure normally takes 30 to 60 minutes. Before the procedure begins, you’ll receive a sedative that will make you sleepy; most patients don’t feel or remember the procedure afterward. During a colonoscopy, tumors or early cancers can be detected and removed, thereby avoiding surgery and saving lives.