A colonoscopy is an examination of the anus, rectum, and colon. A long narrow flexible tube with a light and camera on the end called a Colonoscope is used in this procedure. A colon cleansing prep and clear liquid diet is required the day prior to the procedure. A colonoscope is inserted through the anus and gently advanced through the entire large intestine. Air is used to inflate the bowel so the physician can visualize the bowel walls. Polyps, inflammation, cancer or other abnormalities may be detected.