A colonoscopy is a medical test using a long tube with a light and a camera on the end of it to look at the lining of the colon and rectum. Biopsies or polyp removal can be accomplished at the same time if needed. Polyps are growths on the lining of the bowel that can turn into cancer. For most people, the most difficult part of the procedure is drinking the liquid for cleaning out the colon. We have tried to make this less difficult with newer preparations.