Procedure used to see inside the colon and rectum.
How the test is performed

During the colonoscopy, patients lie on their left side on an examination table. In most cases, a light sedative, and a possibly pain medication, helps keep patients relaxed. Deeper sedation may be required in some cases.
The doctor inserts a long flexible, lighted tube called a colonoscope, or scope, into the anus and slowly guides it through the rectum and into the colon. The scope inflates the large intestine with air or carbon dioxide gas to give the doctor a better view. A small camera mounted on the scope transmits a video image from inside the large intestine, allowing the doctor to carefully examine the intestinal lining. The doctor may ask the patient to move periodically so the scope can be adjusted for better viewing. Once the scope has reached the opening to the small intestine, it is slowly withdrawn and the lining of the large intestine is carefully examined again. Bleeding and puncture of the large intestine are possible but uncommon complications of a colonoscopy.

How to prepare for the test

All solids must be emptied from the gastrointestinal tract by following a clear liquid diet for 1 to 3 days prior to the procedure.

Acceptable liquids include:

  • Fat-free bouillon or broth
  • Strained fruit juice
  • Water
  • Plain coffee
  • Plain tea
  • Sports drinks such as Gatorade
  • Gelatin

A laxative or an enema may be required the night before the colonoscopy. Patients should inform the doctor of any medical conditions and any medications, vitamins or supplements taken regularly, including Aspirin, Arthritis medications, Blood thinners, Diabetes medications, vitamins that contain iron, etc.


A colonoscopy usually takes 30-60 minutes. Cramping or bloating may occur during the first hour after the procedure. The sedative takes time to completely wear off. Patients may need to remain at the clinic for 1 to 2 hours after this procedure. Full recovery is expected by the next day. Discharge instructions should be carefully read and followed.