Mayo Clinic Health Manager
Get free personalized health guidance for you and your family.
Get Started
About our e-newsletters
- Free e-newsletters
- Mayo Clinic expertise
- We do not share your e-mail address
Housecall, our weekly general-interest e-newsletter, keeps you up to date on a wide variety of health topics with timely, reliable, practical information, recipes, blogs, questions and answers with Mayo Clinic experts and more. Our biweekly topic-specific e-newsletters also include blogs, questions and answers with Mayo Clinic experts, and other useful information that will help you manage your health.
Housecall Archives
Mayo Clinic Housecall
Stay up to date on the latest health information.
What you get
- Free weekly e-newsletter
- Mayo Clinic expertise
- Recipes, tools and other helpful information
- We do not share your e-mail address
How you prepare
By Mayo Clinic staffBefore 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. He or she may ask you 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.
Because emptying the colon can be uncomfortable, researchers are studying ways to minimize or eliminate the need for colon preparation before virtual colonoscopy. In one technique, preparation is simply drinking a smoothie containing barium — a metallic compound — with each meal the day before the exam. The barium attaches to the food, which allows doctors to distinguish between stool and abnormal tissue during the virtual colonoscopy. However promising, more research is needed before minimal-preparation virtual colonoscopy is widely available.
- Schilling McCann JA, ed. Diagnostic Tests. Philadelphia, Pa.: Lippincott Williams & Wilkins; 2007:106.
- Virtual colonoscopy. National Digestive Diseases Information Clearinghouse. http://digestive.niddk.nih.gov/ddiseases/pubs/virtualcolonoscopy. Accessed March 18, 2009.
- Cancer imaging. National Cancer Institute. http://imaging.cancer.gov/imaginginformation/cancerimaging/page9. Accessed March 18, 2009.
- Levin B, et al. Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: A joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. Gastroenterology. 2008;134:1570.
- Fletcher RH. Screening strategies in patients at average risk for colorectal cancer. http://www.uptodate.com/home/index.html. Accessed March 18, 2009.
- Weinberg DS. In the clinic: Colorectal cancer screening. Annals of Internal Medicine. 2008;148:ITC2-1.
- Kruskal JB. Computed tomographic colonography. http://www.uptodate.com/home/index.html. Accessed March 18, 2009.
- Yee J. Patient preparation for CT colonography. In: Lefere P, ed. Virtual Colonoscopy: A Practical Guide. New York, N.Y.: Springer; 2006:23.
- Johnson CD, et al. Accuracy of CT colonography for detection of large adenomas and cancers. New England Journal of Medicine. 2008;359:1207.
