Colorectal Polyps Missed with Optical Colonoscopy Despite Previous Detection and Localization with CT Colonography.
OBJECTIVE
To retrospectively evaluate and characterize nondiminutive colorectal polyps prospectively detected by using computed tomographic (CT) colonography but not confirmed with subsequent nonblinded optical colonoscopy (OC).


METHODS
This study was institutional review board approved; the need for signed informed consent was waived. Over 113 months, 9336 adults (mean age, 57.1 years) underwent CT colonography, which yielded 2606 nondiminutive (≥6 mm) polyps. Of 1731 polyps that underwent subsequent nonblinded OC (ie, endoscopists provided advanced knowledge of specific polyp size, location, and morphologic appearance at CT colonography), 181 (10%) were not confirmed with initial endoscopy (ie, discordant), of which 37 were excluded (awaiting or lost to follow-up). After discordant polyp review, 66 of the 144 lesions were categorized as likely CT colonography false-positive findings (no further action) and 78 were categorized as potential OC false-negative (FN) findings.


RESULTS
Thirty-one of 144 (21.5%) of all discordant lesions were confirmed as FN findings at OC, including 40% (31 of 78) of those with OC and/or CT colonography follow-up. OC FN lesions were an average of 8.5 mm ± 3.3 in diameter and were identified with higher confidence at prospective CT colonography (on a 3-point confidence scale: mean, 2.8 vs 2.3; P = .001). OC FN findings were more likely than concordant polyps to be located in the right colon (respectively, 71% [22 of 31] vs 47% [723 of 1535]; P = .010). Most (81% [21 of 26]) OC FN lesions that were ultimately resected were neoplastic (adenomas or serrated lesions), of which 43% (nine of 21) were characterized as advanced lesions, and 89% (eight of nine) of advanced lesions occurred in the right colon.


CONCLUSIONS
In clinical practice, polyps prospectively identified with CT colonography but not confirmed with subsequent nonblinded (ie, despite a priori knowledge of the CT colonography findings) OC require additional review because a substantial proportion may be FN findings. Most FN findings found with OC demonstrated clinically significant histopathologic results, and a majority of advanced lesions occurred in the right colon.
From the Department of Radiology (B.D.P., D.H.K., P.J.P.), Department of Medicine, Division of Gastroenterology and Hepatology (J.M.W.), and Department of Pathology (K.A.M.), University of Wisconsin School of Medicine and Public Health, 750 Highland Ave, Madison, WI 53705.
B Dustin
BD
Pooler
From the Department of Radiology (B.D.P., D.H.K., P.J.P.), Department of Medicine, Division of Gastroenterology and Hepatology (J.M.W.), and Department of Pathology (K.A.M.), University of Wisconsin School of Medicine and Public Health, 750 Highland Ave, Madison, WI 53705.
David H
DH
Kim
From the Department of Radiology (B.D.P., D.H.K., P.J.P.), Department of Medicine, Division of Gastroenterology and Hepatology (J.M.W.), and Department of Pathology (K.A.M.), University of Wisconsin School of Medicine and Public Health, 750 Highland Ave, Madison, WI 53705.
Jennifer M
JM
Weiss
From the Department of Radiology (B.D.P., D.H.K., P.J.P.), Department of Medicine, Division of Gastroenterology and Hepatology (J.M.W.), and Department of Pathology (K.A.M.), University of Wisconsin School of Medicine and Public Health, 750 Highland Ave, Madison, WI 53705.
Kristina A
KA
Matkowskyj
From the Department of Radiology (B.D.P., D.H.K., P.J.P.), Department of Medicine, Division of Gastroenterology and Hepatology (J.M.W.), and Department of Pathology (K.A.M.), University of Wisconsin School of Medicine and Public Health, 750 Highland Ave, Madison, WI 53705.
Perry J
PJ
Pickhardt
D003111:Colonic Polyps / Q000000981:diagnostic imaging* / Q000601:surgery; D023881:Colonography, Computed Tomographic; D003113:Colonoscopy; D003951:Diagnostic Errors / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies