• Can Capsule Colonoscopy Accurately Detect Polyps and Adenomas?

Can Capsule Colonoscopy Accurately Detect Polyps and Adenomas?

In an average-risk screening population, capsule colonoscopy identified individuals with polyps and adenomas with high levels of specificity, researchers report in the May issue of Gastroenterology. This procedure might be useful for patients who cannot undergo colonoscopy or who had incomplete colonoscopies.

Capsule endoscopy, which involves an ingestible pill-sized endoscope that contains a tiny wireless video camera, is a valuable technology for imaging the gastrointestinal tract, but there have been challenges in adapting it to image the colon. Recent advances have increased the number of images that can be captured per second and the angle of view.

Douglas Rex et al performed a prospective study to evaluate the ability of a recently developed capsule to identify patients with polyps 6 mm or larger, evaluating data from 695 average-risk subjects. The subjects underwent capsule colonoscopy followed by conventional colonoscopy (the reference) several weeks later, at medical centers in the United States or Israel.

Rex et al found that capsule colonoscopy accurately identified subjects with 1 or more polyps 6 mm or larger with 81% sensitivity and 93% specificity. The technique identified individuals with polyps 10 mm or larger with 80% sensitivity and 97% specificity. It also identified subjects with 1 or more conventional adenomas 6 mm or larger with 88% sensitivity and 82% specificity, and those with adenomas 10 mm or larger with 92% sensitivity and 95% specificity (see figure).

Accuracy of capsule endoscopy in detecting at least 1 polyp (blue) and at least 1 conventional adenoma (red) 6 mm or larger and 10 mm or larger in size with matching lesions by segment. Error bars indicate 95% confidence intervals.

Accuracy of capsule endoscopy in detecting at least 1 polyp (blue) and at least 1 conventional adenoma (red) 6 mm or larger and 10 mm or larger in size with matching lesions by segment. Error bars indicate 95% confidence intervals.

Sessile serrated polyps and hyperplastic polyps accounted for 26% and 37%, respectively, of false-negative findings from capsule analyses.

Sessile serrated polyps are commonly flat or sessile, pale in color, and subtle in appearance when viewed by colonoscopy. Colonoscopists have more variability in the detection of sessile serrated polyps compared with conventional adenomas. Rex et al therefore state that additional studies are needed to understand the appearance of serrated lesions by capsule colonoscopy and improve their detection.

The authors explain that computed tomography colonography (CTC) detects adenomas 6 mm or larger with 78% sensitivity—a level comparable to that observed in this study. Rex et al say that because CTC and capsule colonoscopy are each used to detect lesions 6 mm or larger, and because CTC is recommended at 5-year intervals for patients with negative results, capsule colonoscopy might also be performed at 5-year intervals in screening.

However, it is important to remember that the bowel preparation for capsule colonoscopy is more extensive than for colonoscopy; technical failures (short transit time and poor preparation) occurred in 9% of patients. It is difficult to perform a colonoscopy examination on the same day as a capsule study, if patients receive a positive result.

Rex et al conclude that colonoscopy is still the standard for the detection of colorectal polyps. Capsule colonoscopy is a good choice for detecting conventional adenomas in patients who cannot undergo colonoscopy or had an incomplete colonoscopy.

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