What is colonoscopy? Colonoscopy is a procedure which enables a gastroenterologist to examine the entire colon. It helps for evaluation of various GI disorders (e.g. hemorrhoids, colon polyps, colon cancer, diverticulosis, inflammatory bowel disease, bleeding, change in bowel habits, abdominal pain) as well as in provides therapy (for example, removal of polyps or control of bleeding). It is also used for screening for colon cancer. Is colonoscopy painful? Will I be sedated? No, colonoscopy is usually not painful! Almost all colonoscopies can be performed using “intravenous sedation” in which you are very drowsy, but comfortable. Understanding preparation before colonoscopy It is extremely important that your colon be thoroughly cleaned before your colonoscopy. This will let the doctor see any abnormalities. Cleansing the colon before a colonoscopy is called bowel preparation. It involves taking medication that causes diarrhea, emptying the colon.