All adults should undergo colon cancer screening beginning at age 50 or earlier, depending upon the risk of developing colorectal cancer. Several tests are currently available, each of which has advantages and disadvantages. The optimal screening test is a screening colonoscopy. A screening colonoscopy is a commonly ordered health screening examination of the colon. The patient is given a mild sedative drug before the procedure. During a colonoscopy, a thin lighted tube is inserted through the rectum allowing the gastroenterologist a full view of the lining of the rectum and the entire colon. If polyps are discovered, they may be removed as part of the procedure.