This is a procedure that allows a physician to visually examine the large intestine (colon and rectum), typically while the patient is sedated. Prior to the exam, patients will drink a laxative to clean out their digestive tract. A colonoscope is used, which is a long thin flexible tube with a light and camera at the end. Tools may be passed through the colonoscope to take tissue samples or remove polyps (abnormal growths on the lining of the intestine) before they turn into cancer. Colonoscopy is generally a very safe procedure, although rare complications can occur, including bleeding, infections, or tearing of the digestive tract.