Colonoscopy is a procedure that enables an examiner (usually a gastroenterologist) to evaluate the inside of the colon (large intestine or large bowel). The colonoscope is a four-foot long, flexible tube about the thickness of a finger with a camera and a source of light at its tip. The tip of the colonoscope is inserted into the anus and then is advanced slowly, under visual control, into the rectum and through the colon usually as far as the cecum, which is the first part of the colon.

The colonoscopy is performed by a doctor experienced in the procedure and lasts approximately 30-60 minutes. Medications will be given into your vein to make you feel relaxed and drowsy. You will be asked to lie on your left side on the examining table. During a colonoscopy, the doctor uses a colonoscope, a long, flexible, tubular instrument about 1/2-inch in diameter that transmits an image of the lining of the colon so the doctor can examine it for any abnormalities. The colonoscope is inserted through the rectum and advanced to the other end of the large intestine.