Computerized tomography (CT) colonography, called Virtual Colonoscopy (VC), uses a CT scanner to produce hundreds of cross-sectional images of your abdominal organs. Those images are digitally manipulated to evaluate the inner surfaces of the colon and provide a detailed view for the absence or presence of abnormalities, such as colon polyps.
VC is more comfortable than conventional colonoscopy for some people because it does not use a colonoscope. As a result, no sedation is needed, and patients can return to usual activities or go home after the procedure without the aid of another person. VC provides clearer, more detailed images than a conventional x ray using a barium enema, sometimes called a lower gastrointestinal (GI) series. It also takes less time than either a conventional colonoscopy or a lower GI series.
If an abnormality is found on VC, it may be recommended that the patient have a traditional colonoscopy performed by a gastroenterologist.
Virtual colonoscopy may be of benefit to:
- Patients with prior incomplete traditional colonoscopy
- Gastroenterologists unable to advance the scope through the entire colon
- Patients who are not medically advised to undergo IV sedation
- Patients with anxiety related to the traditional endoscopic procedure or sedation
In most cases, VC is not reimbursed by medical insurance. However, there may be exceptions if a patient is not able to undergo a regular colonoscopy due to medical reasons.
Preparation and Procedure
As with conventional colonoscopy, the success of the exam depends largely on how well you clear your colon. Virtual Colonoscopy (VC) does require a bowel preparation the day prior to the scan, which is a combination of low residual foods, water, magnesium citrate, bisacodyl tablets and a suppository. The preparation kit is given directly to the patient, and contains all the necessary medications and instructions for the test.
To make the images, your colon is filled with carbon dioxide by inserting a small catheter inside the rectum. You lie on your side and your back while the images are made. You may be asked to hold your breath for several seconds to limit abdominal movement and avoid distorting the images.
VC is typically faster than traditional colonoscopy. A scan of your entire colon takes about 10 minutes.
A Virtual Colonoscopy is not advisable for patients with rectal bleeding, history of diverticulitis, Crohn's Disease or those who have a recent colonoscopy with positive findings.
