Effect of a retrograde-viewing device on adenoma detection rate during colonoscopy: the TERRACE study

Gastrointest Endosc. 2011 Mar;73(3):480-9. doi: 10.1016/j.gie.2010.09.004. Epub 2010 Nov 10.


Background: Although colonoscopy is currently the optimal method for detecting colorectal polyps, some are missed. The Third Eye Retroscope provides an additional retrograde view that may detect polyps behind folds.

Objective: To determine whether the addition of the Third Eye Retroscope to colonoscopy improves the adenoma detection rate.

Design: Prospective, multicenter, randomized, controlled trial.

Setting: Nine European and U.S. centers.

Patients: Of 448 enrolled subjects, 395 had data for 2 procedures.

Interventions: Subjects underwent same-day tandem examinations with standard colonoscopy (SC) and Third Eye colonoscopy (TEC). Subjects were randomized to SC followed by TEC or TEC followed by SC.

Main outcome measurements: Detection rates for all polyps and adenomas with each method.

Results: In the per-protocol population, 173 subjects underwent SC and then TEC, and TEC yielded 78 additional polyps (48.8%), including 49 adenomas (45.8%). In 176 subjects undergoing TEC and then SC, SC yielded 31 additional polyps (19.0%), including 26 adenomas (22.6%). Net additional detection rates with TEC were 29.8% for polyps and 23.2% for adenomas. The relative risk of missing with SC compared with TEC was 2.56 for polyps (P < .001) and 1.92 for adenomas (P = .029). Mean withdrawal times for SC and TEC were 7.58 and 9.52 minutes, respectively (P < .001). The median difference in withdrawal times was 1 minute (P < .001). The mean total procedure times for SC and TEC were 16.97 and 20.87 minutes, respectively (P < .001).

Limitations: Despite randomization and a large cohort, there was disparity in polyp prevalence between the 2 groups of subjects.

Conclusion: The Third Eye Retroscope increases adenoma detection rate by visualizing areas behind folds. (

Clinical trial registration number: NCT01044732.).

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / diagnosis*
  • Adenoma / diagnosis*
  • Adult
  • Aged
  • Aged, 80 and over
  • Colonic Polyps / diagnosis*
  • Colonoscopes
  • Colonoscopy / instrumentation*
  • Colorectal Neoplasms / diagnosis*
  • Female
  • Humans
  • Intention to Treat Analysis
  • Male
  • Middle Aged
  • Prospective Studies
  • Young Adult

Associated data

  • ClinicalTrials.gov/NCT01044732