Virtual colonoscopy (VC) is a medical imaging procedure that uses x-rays and computers to produce two- and three-dimensional images of the colon (large intestine) from the lowest part, the rectum, all the way to the lower end of the small intestine and display them on a screen. The procedure is used to diagnose colon and bowel disease, including polyps, diverticulosis and cancer. VC is performed with computed tomography (CT).
 
Procedure
Preparation for VC is similar to the one used for conventional colonoscopy. The patient is asked to take laxatives at home the day before the procedure to clear stool from the colon. A suppository is also used to cleanse the rectum of any remaining fecal matter.

The examination takes about 10-15 minutes and does not require sedatives. A very thin tube is inserted into the rectum, so that air can be pumped through the tube in order to inflate the colon for better viewing. During the procedure, the patient is first placed in a supine (on the back) and then prone (on the stomach) positions on the examination table.

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. The patient is asked to hold his/her breath during the scan to avoid distortion on the images.

After the examination, the information from the scanner must be processed to create the computer picture or image. A radiologist evaluates the results to identify any abnormalities. The patient may resume normal activity after the procedure, but if abnormalities are found the patient may need to undergo a conventional colonoscopy.

Is this is a painful procedure?
NO. When the air is introduced in the colon some patients experience minimal temporary abdominal cramping or "gas pains." This resolves very quickly as the gas is removed through the tube.

Advantages:

• VC is more comfortable than conventional colonoscopy for most people because it does not use a colonoscope. As a result, no sedation is needed, and the patient can return to his/her usual activities or go home after the procedure without the aid of another person. There is no need to pass an endoscope into the colon which can be painful and invasive and also carries risks of serious complications such as bleeding or perforation of the colon. Instead of expanding the colon with an endoscopic tube, Virtual Colonoscopy expands the colon comfortably with air.
• Preparation for the exam is somewhat easier than for Conventional Colonoscopy.
• NO risk of colonic perforation (1:1000 risk noted for Conventional Colonoscopy).
• It is capable of evaluating the entire colon including large bowel areas upstream from any obstructing lesions or anatomy that prevent passage of an endoscope. Conventional Colonoscopy can be incomplete 10 to 20% of the time.
• Virtual Colonoscopy is significantly less expensive than Conventional Colonoscopy and its related necessary services.
• 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.
• Radiologist will also have a chance to evaluate the bowel wall and other abdominal organs (Liver, Gall Bladder, Spleen, Adrenal Glands, Pancreas and Kidneys) as well as the spine and condition of the blood vessels. This option is obviously not available to the Conventional Colonoscopy operator who can see only the inner walls of the colon.

What are some of the Risk Factors for Colon Cancer?

• Age (Colorectal Cancer usually occurs in people over 50 years old).
• High Fat / Low Fiber Diet (A common diet in North America).
• Genetic / Hereditary Disorders (Familial Polyposis, Crohns and Ulcerative Colitis).

What are some of the Warning signs?

• Bleeding from your rectum or blood in the toilet after a bowel movement.
• A change in the shape or caliber of your stool.
• Continuous cramping in the lower stomach.
• A feeling of discomfort or an urge to have a bowel movement but no ability to pass stool.

Who should get scanned?
The indications for Virtual Colonoscopy include patients that require screening for colonic polyps (the most common reason), patients that have had an incomplete or failed conventional colonoscopy or patients that require preoperative assessment of the colon proximal to an occlusive cancer (defined as a tumor that cannot be traversed endoscopically).

The American Cancer Society recommends screening to begin for men and women at 50 years of age. This can be lower if the person has a family history or other concerns. Repeat scanning is appropriate at 3 to 5 year intervals if the colon is free of polyps, or sooner if a small polyp is found.