Colonoscopy is a test that allows the doctor to look at the inner lining of the large intestine (rectum and colon).A thin, flexible tube called a colonoscope is used to look at the colon. A colonoscopy helps find ulcers, colon polyps, tumors, and areas of inflammation or bleeding. During a colonoscopy, tissue samples can be collected (biopsy) and abnormal growths can be taken out. Colonoscopy can also be used as a screening test to check for cancer or precancerous growths in the colon or rectum (polyps).The colonoscope is a thin, flexible tube that ranges from 48 in. (122 cm) to 72 in. (183 cm) long. A small video camera is attached to the colonoscope so that the doctor can take pictures or video of the large intestine (colon). The colonoscope can be used to look at the whole colon and the lower part of the small intestine.Before this test, the colon needs to be cleaned using a liquid (colon prep). Colon preps may be taken the evening before the test. The colon prep causes loose, frequent stools and diarrhea so that the colon will be empty and absolutely clean for the test. This solution needs to be taken in large volumes upto 2 liters. Usually Pepsi or Sprite is added to this drink to conceal its bitter taste.Colonoscopy is one of many tests that may be used to screen for colon cancer. Which screening test you choose depends on your risk, your preference, and your doctor. Talk to your doctor about what puts you at risk and what test is best for you. Why It Is Done? Colonoscopy is done to:Check for colorectal cancer or polyps. Tests are recommended by the American Cancer Society (ACS), the American College of Gastroenterologists (ACG), the American Gastroenterological Association (AGA), and the U.S. Preventive Services Task Force (USPSTF). These groups recommend routine testing for people age 50 and older who have a normal risk for colorectal cancer.Your doctor may recommend earlier or more frequent testing if you have a higher risk for colorectal cancer. Talk to your doctor about when you should be tested.Check for the cause of blood in the stool or rectal bleeding.Check for the cause of dark or black stools.Check for the cause of chronic diarrhea.Check for the cause of iron deficiency anemia.Check for the cause of sudden, unexplained weight loss.Check the colon after abnormal results from a stool test or a barium enema test.Watch or treat inflammatory bowel disease (IBD).Check for the cause of long-term, unexplained belly pain. How is done? This procedure is performed under short anaesthesia and it takes about 20 30 minutes to complete the procedure. Double balloon enteroscopy Double balloon enteroscopy (DBE), also known as "push-pull enteroscopy" or the "double-bubble", is a new endoscopic technique that allows pan-enteric (complete) examination of the small bowel. This procedure is performed under anaesthesia and takes abot an hour to hour and a half to complete. A very long endoscope is used for this procedure and is passed through the mouth. DBE and capsule endoscopy in combination are two of the most powerful, non-invasive and easy ways to investigate the small bowel. Both tests are associated with minimal discomfort and a very low complication rate. Depending on the indication, DBE may offer patients an alternative to surgery. With DBE it is possible to: Examine parts of the small bowel that are usually difficult to reach Diagnose and assess small bowel diseases and disorders Investigate the small bowel when X-rays, barium follow through, enteroclysis, CT or MRI scans show abnormalitiesns for surgery when these need to be removed