How you prepare

By Mayo Clinic Staff

Before a virtual colonoscopy, you'll need to clean out (empty) your colon. Any residue in your colon may obscure the images taken during the exam.

To empty your colon, follow your doctor's instructions carefully. You may be asked to:

  • Follow a special diet the day before the exam. Typically, you won't be able to eat the day before the exam. Drinks may be limited to clear liquids — plain water, tea and coffee without milk or cream, broth, and clear carbonated beverages. You may not be able to eat or drink anything after midnight the night before the exam.
  • Take a laxative the night before the exam. Your doctor may suggest taking a laxative, either in pill or liquid form. You may also need to use a suppository to clear any remaining residue in your colon.
  • Take medication to identify stool in your colon. Before the exam, you may need to take a prescription stool-tagging medication. The medication will help the doctor differentiate between colon abnormalities and stool residue.
  • Adjust your usual medications. Remind your doctor of your medications at least a week before the exam. You may need to temporarily stop taking certain medications days or hours before the exam.
Jun. 18, 2011