What Is the Bowel Prep for a Colonoscopy?

For a physician to get a clear picture of a patient's intestinal tract during a colonoscopy, the tract cannot contain any food or stool. A procedure called a bowel prep is used to allow the patient to empty out all or nearly all of the contents of his or her intestines, making a colonoscopy possible.

Liquid Diet

• For a period of from one to three days prior to the colonoscopy, a doctor will instruct a patient to stay on a liquid diet. However, patients cannot consume any liquid that contains red or purple dye, as this can interfere with the clarity of the procedure.

Allowable Liquids

• A patient can drink liquids such as water, plain coffee or tea, fat-free broth and certain flavors of Gatorade the day before their colonoscopy.

Function

• The typical bowel prep involves the patient taking a laxative mixture during the late afternoon or evening before the colonoscopy. This will precipitate diarrhea that will "clean out" the digestive tract.

Frequent Trips

• The bowel preparation phase of a colonoscopy is often more unpleasant than the colonoscopy is, as the patient needs to makes frequent trips to the bathroom as the laxatives induce constant bowel movements.

Laxatives

• Laxatives that contain such compounds as polyethylene glycol and magnesium citrate are available for patients to take to cause the bowel movements necessary to empty the digestive tract.