title: Left-sided polyps detected at screening CT colonography: do we need complete optical colonoscopy for further evaluation?
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Radiology, University of Wisconsin School of Medicine and Public Health, E3/311 Clinical Science Center, 600 Highland Ave, Madison, WI 53792-3252, USA. ppickhardt2@uwhealth.org
authors.forename: Perry J
authors.initials: PJ
authors.lastname: Pickhardt
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Durick
authors.forename: B Dustin
authors.initials: BD
authors.lastname: Pooler
authors.forename: Cesare
authors.initials: C
authors.lastname: Hassan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003111:Colonic Polyps / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D023881:Colonography, Computed Tomographic; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012812:Sigmoidoscopy