Easing the prep for a colonoscopy

Easing the prep for a colonoscopy (Paul Taylor, Image Bank / November 12, 2012)

Prepopik, a combination of magnesium oxide and citric acid with sodium picosuflate, isn't widely available.

Moreover, the studies used for FDA approval showed that it did not cleanse the colon as well as some other methods, said Gerard, lead author of the Gatorade/MiraLAX study. Moreover, many patients do not like the taste of magnesium citrate. Side effects include headaches, nausea and vomiting.

Other drugs include oral sodium phosphate tablets, such as OsmoPrep and Visicol, which are available by prescription. OsmoPrep involves taking 32 pills along with drinking 64 ounces of clear liquids.

Over-the-counter oral sodium phosphate products were withdrawn from the market after the FDA warned in 2008 that they were associated with acute phosphate nephropathy, which can result in kidney failure and a lifetime of dialysis.

CT colonography

A CT colonography, also called a virtual colonoscopy, is a standard CT scan of the abdomen. The 2-D image is digitally reconstructed into 3-D, allowing the colon to be viewed in much the same way as it is during a colonoscopy, said Dr. David Greenwald a spokesman for the American Society for Gastrointestinal Endoscopy.

CT colonography is "very accurate when looking for large polyps in the colon," he said. "It's not as accurate as traditional colonoscopy in detecting smaller polyps, some of which can be premalignant."

Polyps are expected to be found in at least 15 to 25 percent of people, and this means the polyps need to be removed during a traditional colonoscopy, which includes a second prep. In some cases, bits of stool stuck to the wall of the colon can be seen or misinterpreted as polyps, causing false positive results, said Greenwald, a professor of clinical medicine at Montefiore Medical Center in New York.

An emerging technology that uses digital subtraction to "virtually" remove the stool and fluid residue could make the prep easier, experts say.

"You drink a fluid that coats the stool and mixes in with the fecal residue," Greenwald said. "Then the computer digitally subtracts it, leaving only polyps." But again, those with polyps would still have to undergo a second prep and a standard colonoscopy.

CT colonography is less invasive than a colonoscopy, doesn't require sedation and can pick up problems outside the colon. But the bottom line: It still requires bowel preparation, insurance rarely pays for it, and the actual procedure can be more uncomfortable because patients aren't sedated.

Still, "about 30 percent of people who went for virtual colonoscopy wouldn't have been screened for colon cancer at all, so it's a nice option to throw in there," Spiegel said.