Friday, May 13, 2011

Virtual Colonoscopy

It’s the word that any 50+ year old cringes at when said: colonoscopy. This invasive exam is usually performed by inserting a long, flexible tube (colonoscope) into the rectum in order to check for polyps that may be cancerous. Colon cancer is the second leading cause of cancer death in the U.S. Yet, only half the people who should be screened actually are due mostly to the discomfort of the procedure.

Recently, a new procedure has started to gain popularity. A virtual colonoscopy (or CT colonography) uses CT scanning equipment to produce high quality pictures of the colon. It uses a much smaller tube which is only inserted 2 to 3 inches into the rectum for half a minute. The tube is much shorter than other colonoscopy procedures and doesn’t require sedation. And, research has provided substantial evidence that virtual colonoscopy is equally able to detect normal sized polyps as fecal occult blood testing, barium enema, and sigmoidoscopy which are the three major colonoscopy procedures.
Though the procedure may be easier, quicker, and as effective compared to the leading procedures, with more research I have found problems.

The CT scanner, which is used during the procedure, exposes the individual to radiation. Radiation from a single CT scan is equivalent to about 100 to 250 plain chest films. Is it effective for a cancer prevention procedure to perhaps cause cancer? Also, CT colonography is not as sensitive as standard colonoscopy for polyps less than 7 mm and some of these polyps may be precancerous. Therefore, a patient may not be able to even detect the polyps until they are large and very cancerous perhaps allowing metastasis. Because of this, doctors recommend a patient has a CT colonography every 3 years.

But with patients already failing to get a normal colonoscopy every 10 years, is it really realistic they would go every 3? Yes getting a virtual colonoscopy over a normal kind seems easier, but it does require that patients take laxatives and not eat for a full day. To some, that is the worst part of getting a colonoscopy. It seems to me that getting a virtual colonoscopy may in fact “bite you in the butt” (literally) in the future.