A Retrograde-Viewing Device Improves Adenoma Detection Rate in Colonoscopies for Surveillance and Diagnostic Workup: ACG International Award: 1402

Purpose: Colonoscopy is the “gold standard” for detecting and removing colorectal polyps. However, standard colonoscopy misses up to 24% of adenomas, and two-thirds of missed adenomas are located behind haustral folds. The Third Eye® Retroscope® (TER) provides an additional, retrograde view that reveals areas behind folds. The Third Eye Retroscope Randomized Clinical Evaluation (TERRACE) found that Third Eye colonoscopy detected 23% additional adenomas compared to standard colonoscopy. We performed a subanalysis of the TERRACE results to determine whether a specific indication for colonoscopy (screening, surveillance or diagnostic workup) was associated with a higher additional adenoma detection rate (ADR) with the TER. Methods: The TERRACE study was a prospective, multicenter, randomized trial with 448 subjects being enrolled, of whom 349 were included in the perprotocol population. In these patients same-day, tandem examinations were performed using the same colonoscope with and without the TER. Subjects were randomized to standard colonoscopy (SC) followed by Third Eye colonoscopy (TEC) (Group A) or vice versa (Group B). Primary outcome measures were detection rates for all polyps and for adenomas. Tandem colonoscopy studies show a “second-pass effect” - i.e., a second look usually finds additional lesions. The ADR in Group B, as a proxy for second-pass effect, was therefore subtracted from ADR in Group A to yield the net additional detection rate attributed to TEC. Results: Overall TERRACE results showed a net additional adenoma detection rate with the TER of 23.2%. The Relative Risk (RR) of missing adenomas with SC vs. TEC was 1.92 (P=0.029). Indications were screening in 176/345 subjects (51.0%), surveillance after previous polypectomy in 87 (25.2%) and diagnostic workup in 82 (23.8%). In 4 subjects no indication was specified. Additional ADRs for TEC compared to SC were 4.4% for screening, 35.7% for surveillance and 55.4% for diagnostic patients. The RR of missing adenomas with SC vs. TEC was 1.11 (P=0.81) for screening, 3.15 (P<0.05) for surveillance and 8.64 (P<0.05) for diagnostic. In the surveillance and diagnostic groups combined, due to additional detection with TEC, 17.5% additional subjects were found to have at least 1 adenoma and 27.3% additional subjects were advised to return for 3-year followup per guidelines (at least 1 advanced adenoma or at least 3 small adenomas).Table: Additional adenoma detection rates for second proceduresConclusion: Use of the TER during colonoscopy allows detection of significantly more adenomas compared to the colonoscope alone. Patients who are being examined for surveillance or diagnostic workup appear to benefit more from the additional retrograde view compared to those undergoing routine screening. (ClinicalTrials.gov Identifier: NCT01044732). Disclosure: Dr. Siersema, Scientific Advisory Board of Avantis Medical Systems. This research was supported by an industry grant from Avantis Medical Systems.