Colonoscopy

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• Having a barium enema within a week before the test. Barium can block your doctor's view of the colon.
• Having stool (feces) in the colon, a colon that has many turns, past surgery on the colon, or a lot of pain during the test.
• Taking iron supplements. This may make your stool turn black and make it hard to clean out the colon. Do not take iron supplements for several days before a colonoscopy.
• Drinking red or purple fluids, such as grape juice or fruit punch.
• Eating red or purple foods, such as grape Popsicles or cherry Jell-O.

Go to previous section	Go to top of page	Go to next section
Author:	Monica Rhodes	Last Updated: August 11, 2008
Medical Review:	Kathleen Romito, MD - Family Medicine Peter J. Kahrilas, MD - Gastroenterology
© 1995-2009 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.