Capsule Colonoscopy Has Low Sensitivity

A swallowed capsule equipped with a video camera didn’t find as many polyps as conventional colonoscopy and missed 5 of 19 cancers. Sensitivity improved with a well-cleaned colon.

Doctors in Europe examined 328 patients who either had colon disease or were suspected of having it with both a capsule colonoscopy and traditional optical colonoscopy.  The capsule contained  tiny video cameras at both ends that transmitted images wirelessly from the upper GI tract and the colon.

Compared to optical colonoscopy the capsule found:

• 64 percent of polyps larger than 5 millimeters (about 1/4 inch)
• 73 percent of advanced adenomas
• 14 of 19 cancers

The PillCam, manufactured by Given Imaging, is about 1 and 1/4 inches long and is swallowed with a sip of water.  Bowel preparation is more extensive for the capsule because it needs some clear liquid to travel through the bowel.  Less than ten percent of patients had mild to moderate side effects from the test, mostly related to bowel prep.  They included abdominal discomfort, nausea and vomiting, and headache.

Andre Van Gossum, MD and the study team concluded,

The use of capsule endoscopy of the colon allows visualization of the colonic mucosa in most patients, but its sensitivity for detecting colonic lesions is low as compared with the use of optical colonoscopy.

In an editorial accompanying the article in the New England Journal of Medicine, Michael Bretthauer, MD, PhD from Oslo University said that the low sensitivity of capsule colonoscopy was a concern.  Because of low sensitivity, the extensive bowel preparation required, and high cost ($1,150) he concluded, “”colon capsule endoscopy cannot be recommended at this time.”

Partial results from another study of capsule colonoscopy, not yet complete, were reported during Digestive Disease Week in early June. Patients in that study were at increased or high risk for colon cancer. Capsule colonoscopy found polyps in 22 percent of patients compared to 21 percent during the optical colonoscopy which followed. Sensitivity for polyps larger than 5 millimeters was 55 percent.

Colon cleansing was a particular issue in this study.  Patients were on a low-residue diet for 3 days before the capsule was swallowed.  They had 3 liters of PEG solution the day before the procedure with a second liter the day of the test.  Additional laxatives were taken during the time the capsule was traveling through their systems.  Despite this bowel prep, adequate bowel cleansing was present in only 55 percent of patients. However, the same bowel cleansing was judged good to excellent for optical colonoscopy in 87 percent.

There were 5 adverse events among the 105 patients, two serious ones including a colon perforation and a cardic problem that might have been related to the bowel prep.

SOURCES: Van Gossum et al., Capsule Endoscopy versus Colonoscopy for the Detection of Polyps and Cancer, New England Journal of Medicine, Volume 361, Number 3, July 16. 2009.

Sacher-Huvelin et al., Wireless Capsule Colonoscopy Compared to Conventional Colonoscopy in Patients At Moderate or Increased Risk for Colorectal Cancer, Digestive Disease Week 2009 Abstract #276.