A gentler, kinder prep for virtual colonoscopy?

Four pills replace liters of laxative

One of the most unpleasant aspects of colorectal cancer screening for many patients is the amount of laxative they must drink the night before. Some become so anxious about drinking so much liquid that they avoid the entire procedure, which puts them at risk of undiagnosed cancer. Under a new practice at Mayo Clinic in Arizona, Scottsdale, four pills replace the multiple liters of laxative for people having a CT colonography, also known as a virtual colonoscopy.

In virtual colonoscopy, computerized tomography (CT) is used to produce hundreds of cross-sectional images of the abdominal organs. In the new Mayo protocol that began this past summer, patients having virtual colonoscopies simply take four tablets of the cleansing agent bisacodyl.

"Our hope is that this will make people less anxious and more likely to get screened and will ultimately result in fewer deaths from colorectal cancer," says C. Daniel Johnson, MD, chair of the Department of Radiology at Mayo Clinic in Arizona.

The development of the new protocol was based on a study by Johnson and published in "Abdominal Imaging" journal last year. The study found that the new four-tablet procedure worked as well as the standard liquid laxative for virtual colonoscopies. The new protocol is not intended for standard colonoscopies because the cleansing requirements between the two procedures differ.

Virtual colonoscopy was found to be highly accurate for detection of intermediate (6-9 m) and large (greater than 1 cm) polyps. Because most patients will not have a polyp, no further workup is necessary. Only the 12% of patients identified with a polyp during a colonography then would need to have a colonoscopy. Because most colon cancer arises from preexisting polyps, detection and removal of these lesions can help eradicate it.

For a video of Johnson talking about the new protocol, go to http://bit.ly/PZfdND.