Health Information
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 Reference barium enema Opens New Window within a week before the test. Barium can block your doctor's view of the colon.
- Not doing a good colon prep before the test. If you still have stool (feces) in the colon, your doctor may cancel the test and you will have to reschedule and do the colon prep again.
- Having 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 ice pops or cherry gelatin.
| By: | Reference Healthwise Staff | Last Revised: Reference December 7, 2011 |
| Medical Review: | Reference Adam Husney, MD - Family Medicine
Reference Arvydas D. Vanagunas, MD - Gastroenterology |
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