Incidental findings raise costs of CT colonography

Virtual colonoscopy finds anomalies outside the colon that require additional tests though they often present no risk to patients. These tests unnecessarily raise the overall cost of healthcare, making CT colonography more expensive than the traditional procedure, according to a study conducted by Dr. Richard S. Bloomfeld, an assistant professor of medicine at Wake Forest University Baptist Medical Center.

Bloomfeld presented the study results at the American College of Gastroenterology meeting in Las Vegas on Oct. 25. While acknowledging that CTC will play a future role in colon cancer screening, Bloomfeld, a gastroenterologist, argues that its time has not yet come.

"It is important to understand the implications of findings outside the colon before we advocate widespread use of this technology," he said.

CTC is intended to detect small growths or polyps so that, if found, they can be removed through a conventional optical endoscope. Research scheduled to be published in the November issue of Radiology supports the conclusion that virtual colonoscopy is as effective as optical endoscopy, when screening for colorectal cancer (DI SCAN, 10/19/06, Virtual colonoscopy offers alternative to endoscopy). The University of Wisconsin-Madison researchers conclude that, because of its increased ease and relative patient comfort, CTC holds the potential to improve compliance for colorectal cancer prevention and screening.

The Wake Forest physicians acknowledge that CTC is better able to see polyps than barium enemas and is nearly as accurate as conventional colonoscopy, noting that most patients report CTC is more comfortable than either procedure. The problem comes when the CT exam results in findings beyond its intended area of application.

Wake Forest study findings outside the colon, such as lung nodules and indeterminate kidney lesions, led to additional testing. This added about $231 to each CTC exam performed during colorectal cancer screening of average risk patients. Bloomfeld and colleagues reported that the suspicious findings discovered outside the colon were often benign.

"Finding things outside the colon on a virtual colonoscopy can be a good thing or a bad thing," he said. "It's a good thing if we find unknown conditions that are treated, but a bad thing if we put people through more invasive tests with risks and additional costs for no reason."