Health Watch - Virtual Colonoscopy?

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Is a less-invasive version of an unpleasant exam as effective?

The best way to detect colon cancer and pre-cancerous polyps in the colon is with an exam called colonoscopy. In this exam, a long, flexible viewing tube is inserted in the rectum and threaded through the colon. The viewing tube allows doctors to see any suspicious polyps on a monitor, and a device on the end of the tube lets doctors remove any suspicious growths. These growths are later tested for cancer.

Needless to say, this isn't a pleasant procedure to undergo. Because of that, some doctors are using "virtual" colonoscopy, in which the colon is given a computed tomography - or CT - scan. In this test, only a narrow rectal catheter is inserted. There are two different techniques for virtual colonoscopy. One gives two-dimensional images in multiple planes. The other gives a three-dimensional image similar to the view doctors see when they do conventional colonoscopy. These exams are more comfortable for patients, but are they as effective?

Doctors at UT Southwestern Medical Center at Dallas say no. In a recent study, they found that the virtual method missed almost half of the larger suspicious polyps found by conventional colonoscopy, and only found a little more than a third of the smaller tumors. But at the same time, virtual colonoscopy may be a benefit because it gets reluctant patients, many of whom avoid the prospect of undergoing an uncomfortable procedure, to have the screening - even though it's not perfect.

Dr. J. Steven Burdick, head of endoscopy for UT Southwestern, added that these results may vary depending on the training of the doctor doing the exam.


June 2004