title: Location of adenomas missed by optical colonoscopy.
abstract: BACKGROUND
  Previous estimates of the adenoma miss rate with optical colonoscopy (OC) are hindered by the use of OC as its own reference standard.
  
  
  OBJECTIVE
  To evaluate the frequency and characteristics of colorectal neoplasms that are missed prospectively on OC by using virtual colonoscopy (VC) as a separate reference standard.
  
  
  METHODS
  Prospective, multicenter screening trial.
  
  
  METHODS
  3 medical centers.
  
  
  METHODS
  1233 asymptomatic adults who underwent same-day VC and OC.
  
  
  METHODS
  Colorectal neoplasms (adenomatous polyps) missed at OC before VC results were unblinded.
  
  
  RESULTS
  Fourteen (93.3%) of 15 nonrectal neoplasms were located on a fold; 10 (71.4%) of these were located on the backside of a fold. Five (83.3%) of 6 rectal lesions were located within 10 cm of the anal verge.
  
  
  CONCLUSIONS
  Estimation of the OC miss rate depended on polyp detection on both VC and second-look OC and therefore underestimates the true OC miss rate, particularly for smaller polyps.
  
  
  CONCLUSIONS
  Most clinically significant adenomas missed prospectively on OC are located behind a fold or near the anal verge. The 12% OC miss rate for large adenomas (>or=10 mm) when state-of-the-art 3-dimensional VC is used as a separate reference standard is increased from the previous 0% to 6% estimates derived by using OC as its own reference standard.
authors.affiliation: Department of Radiology, University of Wisconsin Medical School, E3/311 Clinical Science Center, 600 Highland Avenue, Madison, WI 53792-3252, USA. ppickhardt@mail.radiology.wisc.edu
authors.forename: Perry J
authors.initials: PJ
authors.lastname: Pickhardt
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Nugent
authors.forename: Pauline A
authors.initials: PA
authors.lastname: Mysliwiec
authors.forename: J Richard
authors.initials: JR
authors.lastname: Choi
authors.forename: William R
authors.initials: WR
authors.lastname: Schindler
mesh_terms: D000236:Adenoma / Q000473:pathology*; D000328:Adult; D023881:Colonography, Computed Tomographic; D003113:Colonoscopy / Q000379:methods*; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D007417:Intestinal Polyps / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies