A novel retrograde-viewing auxiliary imaging device (Third Eye Retroscope) improves the detection of simulated polyps in anatomic models of the colon.

BACKGROUND: Colonoscopy is the "gold standard" for colorectal polyp and cancer detection, but important lesions may be missed on the proximal aspect of haustral folds, rectal valves, or flexures.

OBJECTIVE: Our purpose was to evaluate a prototype auxiliary imaging device that extends beyond the colonoscope's tip, providing a continuous retrograde view to detect lesions missed by the forward-viewing colonoscope.

DESIGN: Three anatomic models of the colon were prepared with simulated polyps, 32% in obvious locations and 68% on the proximal aspect of folds. Six endoscopists examined each model with two methods. Method A used a standard video colonoscope. Method B involved an identical colonoscope with a retrograde-viewing auxiliary device positioned within its instrument channel. Order of testing was randomized and blinded.

SETTING: Laboratory bench.

MAIN OUTCOME MEASUREMENTS: Detection rates for simulated polyps.

RESULTS: Of 78 "obvious" polyps, 69 (88%) and 70 (90%) were detected by methods A and B, respectively (P > .9). In contrast, of 162 polyps on proximal aspects of folds, 20 (12%) and 131 (81%) were detected by methods A and B, respectively (P < .00001).

LIMITATIONS: Limitations resulted from (1) use of commercially available anatomic models in which haustral folds are less prominent and more rigid than in humans and (2) evaluation of a prototype device that had larger size and narrower angle of view than the planned production model and that was fixed in relation to the colonoscope.

CONCLUSIONS: In simulated testing, a retrograde-viewing auxiliary imaging device used with a standard video colonoscope significantly improves detection rates of simulated polyps and promises to enhance the diagnostic yield of colonoscopy in humans.