Virtual Colonoscopy—Good Results Without the Bad Preparation

The list of medical procedures no one welcomes is long and varied, but pretty much everyone would opt never to have a colonoscopy if it weren’t necessary.

It’s not so much the procedure that’s a problem, it’s the preparation-a diet restricted to clear liquids for 24 hours, and the ingestion of a nasty bowel-clearing drink no one will ever confuse with refreshment.

We recently wrote about the mixed messages that surround colon cancer scans, but they’re advisable for many people. Thanks to recent research, things could be looking up for the colonoscopy crowd.

As reported on MedPage Today, virtual colonoscopy, in which the lower intestine and colon are scanned externally by CT technology instead of viewed with an invasive probe, correctly identified 9 in 10 patients with larger adenomas-masses, or polyps, that aren’t cancerous but carry that potential. Standard optical colonscopy generally detects 9½ out of 10 such polyps.

Smaller masses, however, might not be be detected as successfully with virtual colonoscopy.

The study results were published in the Annals of Internal Medicine.

The less invasive procedure eliminates the need for the laxative that precedes traditional colonoscopy, but patients still ingest a solution; it contrasts stool on the image as different from other bowel contents. The interpretive software digitally erases the stool from anything a radiologist needs to see.

Although virtual technology does not appear to depict polyps smaller than 10 mm as reliably as larger masses, the vast majority of polyps that lead to cancer and affect survival outcomes are larger than 10 mm. For people who can’t-or won’t-tolerate the laxative bowel preparation, the CT scan might be the only way they get screened.

The study involved multiple facilities and 605 adults 50 to 85 years old who were at average to moderate risk for colon cancer. All were screened by both methods. Only four of the 26 lesions detected were smaller than 10 mm. All of the confirmed cancers were larger than 10 mm.

More than 6 in 10 study subjects said they’d opt for the virtual procedure over standard colonoscopy in the future. About 5 in 100 received additional diagnostic tests because something other than suspicious polyps were detected.

In addition to the loathsome preparation, traditional colonoscopy has inherent risks, primarily perforation of the bowel. Some people also might react to the sedative.

If you’re scheduled for a colonoscopy, discuss the pros and cons of each type of screening, including sigmoidoscopy, which is invasive, but requires less preparation than colonoscopy and usually no sedation. But it views only the lower part of the colon instead of the whole thing. So a lot of specialists liken it to undergoing mammography of just one breast.

Despite the news on virtual colonoscopy, for most people, conventional colonoscopy remains what doctors call the “gold standard.”