Left-sided polyps detected at screening CT colonography: do we need complete optical colonoscopy for further evaluation?

PURPOSE

To estimate the relative yield of therapeutic flexible sigmoidoscopy compared with complete optical colonoscopy for isolated left-sided polyps (≥6 mm in diameter) identified at screening computed tomographic (CT) colonography.

MATERIALS AND METHODS

This retrospective institutional review board-approved and HIPAA-compliant study included a review of CT colonographic screening results in 6570 consecutive asymptomatic adults (3551 women, 3019 men; mean age, 56.8 years ± 7.3 [standard deviation]). Of 887 (13.5%) patients with cases positive for nondiminutive polyps (≥6 mm), a subset of 171 patients met the inclusion criteria (a) of having left-sided-only lesions of 6 mm or larger identified at CT colonography (rectum-to-splenic flexure) and (b) of undergoing subsequent evaluation with complete optical colonoscopy. CT colonography-optical colonoscopy concordance and proximal-versus-distal diagnostic yield at optical colonoscopy were assessed. The 95% confidence intervals (CIs) were calculated for relevant results.

RESULTS

From the study group of 171 patients, a total of 234 left-sided lesions of 6 mm or larger were prospectively reported at CT colonography, of which 222 (94.9%; 95% CI: 91.3%, 97.0%) were confirmed as true-positive findings at optical colonoscopy. With optical colonoscopy, an additional 17 benign left-sided polyps of 6 mm or larger (13 small, four large) were found in 11 patients, resulting in a total left-sided yield of 239 nondiminutive lesions, including 137 small polyps (6-9 mm) and 102 large lesions (≥10 mm), 160 neoplasms, 82 advanced adenomas, and seven cancers. Evaluation of the colon proximal to the splenic flexure in this cohort yielded eight small and two large benign polyps in nine patients but no proximal cancers or histologically advanced lesions.

CONCLUSION

For patients with left-sided-only polyps detected at CT colonography, the additional yield of complete optical colonoscopy beyond the expected reach of flexible sigmoidoscopy is very low and may not justify the added costs, potential risks, and procedural time.