Colonoscopy is a procedure that is done to thoroughly examine the lining of the colon and rectum. What happens is that a long flexible tube is inserted via the anus and advanced along the rectum and colon until it reaches the beginning of the colon. A screening colonoscopy is a good idea for those aged 50 years and above (younger for individuals with a family history of colorectal cancer). It may also be recommended for those who display symptoms suggesting problems in the colon or rectum, such as bleeding, change in bowel habits and unexplained abdominal symptoms. The procedure is used as well for follow-up examinations of patients with a history of colon cancer or polyps.

The patient will be given potent laxatives to clear the colon of stools. In most cases, if the procedure is to be done in the morning, the patient will be asked to take the laxatives and purge the night before. For an afternoon procedure, expect to be asked to clear the bowels on the morning of the examination. To help clear the bowels, patients will be encouraged to take in as much fluid in their diet as possible. Foods high in fibre like fruit and vegetables, however, are discouraged, starting two days prior to the colonoscopy. Patients who are on aspirin or other blood thinning medications will also be advised by the doctor when to stop those medications. Multiple trips to the toilet should be expected after the laxatives have been ingested. Many patients have expressed that this is the worst part of the entire procedure.