Virtual colonoscopy (VC) uses X-rays and computers (CT scan or MRI) to produce two- and three- dimensional images of the large intestine (colon), the rectum, and the small intestine. The images will display on a screen. These images are clear and more detailed than a conventional X-ray using a barium enema. The procedure is used to diagnose colon and bowel disease, including polyps, diverticulosis, and cancer.
During a VC, your doctor cannot take tissue samples or remove polyps. A conventional colonoscopy must be performed if abnormalities are found. Also, VC does not show as much detail as a conventional colonoscopy. Abnormal growths (polyps) smaller than 10 mm in diameter may not show up on the images.
BEFORE THE PROCEDURE
Preparations for VC vary. But you will usually be asked to take laxatives or other oral agents at home the day before the procedure. This is to clear stool from your colon. You may also be asked to use a suppository. This is to cleanse your rectum of any remaining fecal matter.
The exam takes about 10 minutes and does not require sedatives.
You will lie on your back on a table.
A thin tube will be inserted into your rectum. Air will be pumped through the tube to inflate the colon for better viewing.
The table moves through the scanner to produce a series of two-dimensional cross-sections along the length of the colon. A computer program puts these images together to create a three-dimensional picture that can be viewed on the video screen.
You will be asked to hold your breath during the scan. This is to avoid distortion on the images.
The scanning procedure is repeated with you lying on your stomach.
AFTER THE PROCEDURE
The information from the scanner must be processed to create the computer picture or image of your colon. The results will be evaluated to identify any abnormalities. Your caregiver may ask you to wait while the test results are analyzed.
If abnormalities are found and you need a conventional colonoscopy, it may be performed the same day.
You may resume normal activity after the procedure.
FOR MORE INFORMATION
American College of Gastroenterology (ACG): www.gi.org
International Foundation for Functional Gastrointestinal Disorders (IFFGD): www.iffgd.org
National Digestive Diseases Information Clearinghouse