Virtual Colonoscopy: How to Counsel Your Patients

Abstract & Commentary

Synopsis: Although safer than traditional colonoscopy, virtual colonoscopy’s lower sensitivity and efficacy coupled with the increased cost would rule against recommending this procedure at the current time.

Source: Cotton PB, et al. JAMA. 2004;291:1713-1719.

Nine major hospital centers participated in this non-randomized, evaluator-blinded study of 615 patients, all of whom were 50 years of age or older, and who were referred for routine colonoscopy. Three hundred and eight patients underwent virtual colonoscopy just prior to the standard colonoscopy. Among the 827 lesions identified, sensitivities for the 2 procedures were as follows: for lesions 6 mm or less, virtual colonoscopy 39% (95% confidence interval [CI], 29.6-48.4%) vs conventional colonoscopy 99% (95% CI, 97.1-99.9% or greater); for lesions 10 mm or more, virtual colonoscopy 55% (95% CI, 39.9-70%) vs 100% for conventional colonoscopy. The specificity for virtual colonoscopy to detect subjects without any lesions at least 6 mm was 90.5% (95% CI, 87.9-91.3%), and for 10 mm lesions 96% (95% CI, 94.3-97.6%). The specificity for conventional colonoscopy was 100% for both. Of the 8 cancers detected, virtual colonoscopy missed 2.

Comment by Frank W. Ling, MD

Here’s another chapter in the evolving book of primary that so many of us obstetrician/gynecologists help our patients thumb through. Clearly this new and sexy approach to screening for colon cancer has caught on in the lay public and lay press. It is fairly routine now that when I recommend that a patient undergoes colon cancer screening that she asks about virtual colonoscopy. These data help us to counsel patients in that tried and true mold: if it sounds too good to be true, it probably is, ie, don’t believe everything you hear. The results of this study would certainly suggest that this technique is not quite ready for our routine recommendation.

Since any lesion on virtual colonoscopy must be biopsied or removed via the conventional route, the patient would not avoid the more invasive procedure in those cases. In addition, many patients would say that it’s not conventional procedure that is so bad, but the bowel prep that precedes it. That is still required for virtual colonoscopy. What about the price? More importantly, will the patient’s insurance company pay for it? Yes, it’s non-invasive and, therefore, safer, but it’s a lot pricier (particularly if the patient has to pay for it herself), and would appear to not be as good a test as conventional colonoscopy.

I was on an airplane a few months ago and a passenger next to me noted that I was working on some medical paperwork. That led us to discussing why he had been to New York for the past 3 days. You guessed it—this resident of Memphis, Tennessee, had been to the Big Apple for his annual physical and a virtual colonoscopy. As I queried further, I found it fascinating that he was in his early 40s, had no cancer risk in his family, and did not have a physician who had recommended the procedure. He had scheduled himself and paid for it because he felt that it was the right thing to do. I guess if you’ve got the time and money, you can decide how to use both.

As always, then, what is our bottom line? Recommend colonoscopy for your patients based on their individual risk factors when it is appropriate and, at least for now, recommend the technique which is best supported by the data—conventional colonoscopy.

Frank W. Ling, MD, Women’s Health Specialists, PLLC, Memphis, Tennessee is Associate Editor of OB/GYN Clinical Alert.