Preparing for Colonoscopy
Knowing what to expect can help eliminate fears and ease discomfort.
Preparation for a colonoscopy means having a clean colon. A doctor’s ability to see inside your colon depends on how thoroughly it is cleared of stool (feces). If your bowel is not completely clean, test results may not be accurate. The exact requirements for preparing for your colonoscopy may vary from the descriptions below as some hospitals or clinics performing colonoscopies have very specific requirements. Be sure to follow the precise instructions given to you by your physician.
To clean the colon, your doctor will send you to your pharmacy to purchase a purgative (a drug that causes evacuation of the bowels) to be taken the day before your colonoscopy. In addition to taking the purgative, you must restrict yourself to a clear liquid diet, and generally stay close to the bathroom. Your doctor may also advise you to modify the way you take some of your other medications in the days leading up to the procedure.
There are several types of purgatives. All are osmotic agents, which work by pulling water from the body into the bowel. They are safe and effective when used for appropriate patients according to the directions, but they vary from patient to patient in tolerability. If a patient does not tolerate a purgative very well, its effect may not be complete, and the colon may not be sufficiently clean to allow a thorough examination.
A commonly used purgative is polyethylene glycol (PEG). Although it comes in four flavoured varieties to disguise the salty taste (Colyte®, PegLyte®, Golytely®, Klean-Prep®), the main disadvantage is having to drink four litres of the solution, which often is too much for a patient to manage.
Nearly one-third of patients who could not tolerate their bowel preparation the first time do not go through with their next colonoscopy. This discouraging situation may change with the availability of a new purgative called Pico-Salax® (magnesium oxide, citric acid, sodium picosulphate), which is already receiving positive feedback from patients. Pico-Salax® is the only dual action purgative, which means it works in two ways (osmotic and stimulant) and it is easier on the body. The stimulant further helps the bowel eliminate fecal matter. Clinical studies show that patients tolerate it better than the other preparations, and experience fewer side effects. It has a pleasant taste that, according to some, is similar to Tang® or tart lemonade, and is a manageable volume to drink (one 5-oz glass, twice during the day). It is important, however, for people to drink at least 4 to 6 large glasses of water or clear liquid following each 5-oz glass dose. Pico-Salax® is also the only purgative that children over the age of one can safely use.
During bowel preparation, drink plenty of clear liquids (if you can see through it you can drink it) to avoid dehydration and to help completely clean out your colon; do not eat any solid foods. Stop drinking clear liquids three hours before the colonoscopy. And remember, stay within close access to a toilet. Your doctor will likely give you a sedative before the colonoscopy, so arrange to have someone take you home afterward.
The key to preventing colorectal cancer is to get screened at the right time and with the right test. It might be the smartest thing you’ve ever done!
Dr. Martin Fishman, Gastroenterologist
First published in The Inside Tract® Newsletter Issue 155 May/June 2006