Virtual colonoscopy (VC) is an imaging or x-ray test that looks for cancer, polyps, or other disease in the large intestine (colon).
A virtual colonoscopy is different from a regular colonoscopy, in which a long, lighted tool called a colonoscope is inserted into the rectum and large intestine.
The test is performed in the radiology department of a hospital or medical center. No sedatives are needed and no scope is used.
A computer combines all the images to form three-dimensional pictures of the colon, which are viewed on a video monitor.
Pictures are also taken while you lie on your stomach.
Everyone undergoing any type of colonoscopy must completely empty their bowels before the exam. This may be done using an enema or laxatives combined with a liquid diet the day before the test. The bowel must be completely emptied until no solid matter remains.
Unfortunately, diarrhea is common during preparation. Drink plenty of clear liquids, such as apple juice and chicken broth, to avoid dehydration.
Make sure you tell your health care provider about any medications you are taking. You will be told which you can take, and which you should temporarily stop. CT and MRI scanners are very sensitive to metals. Do not wear jewelry the day of your exam. You will be asked to wear a hospital gown for the procedure.
The x-rays are painless. Pumping air into the colon can create cramping or gas pains.
Virtual colonoscopy may be performed to:
Your doctor may want to do a conventional colonoscopy instead of a virtual colonoscopy. The reason is that virtual colonoscopy does not allow the doctor to remove tissue samples or polyps.
Other times, a virtual colonoscopy is done if your doctor was not able to move the flexible tube all the way through the colon during a conventional colonoscopy.
Normal findings are images of a healthy intestinal tract.
A regular colonoscopy may be done (on a different day) after a virtual colonoscopy if:
Risks of virtual colonoscopy include:
Differences between virtual and conventional colonoscopy include:
Colonoscopy - virtual; CT colonography
Burt RW, Barthel JS, Dunn KB, David Ds, Drelichman E, Ford JM, et al. NCCN clinical practice guidelines in oncology. Colorectal cancer screening. J Natl Compr Canc Netw. 2010;8:8-61.
Bresalier RS. Colorectal cancer. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 123.
Updated by: George F. Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program, San Diego, California. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, and Stephanie Slon. 10/08/12
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