Medical Content Created by the Faculty of the
Harvard Medical School
Tell your doctor if there is any chance that you might be pregnant. If you have diabetes and take insulin, discuss this with your doctor before the test.
You will be given very specific instructions to ensure that your colon is completely empty before the test. You may be told to eat only a light breakfast and a liquid lunch and dinner (such as broth and fruit juice) on the day before the test. You may also be instructed to drink a large amount of clear liquid between meals and to avoid dairy products. You will need to take a laxative, a medicine that stimulates your intestine to move things through more quickly, so that you have a bowel movement to empty the colon. It is a good idea to stay at home or at least near a bathroom for a few hours after taking the laxative. On the day of the test, do not eat any breakfast.