Retrograde-viewing device influences adenoma detection during colonoscopy

The latest issue of the Gastroentestinal Endoscopy evaluates the impact of experience with a retrograde-viewing device on adenoma detection rates and withdrawal times during colonoscopy.

Colonoscopy has been adopted as the preferred method to screen for colorectal neoplasia in the United States.

However, lesions can be missed because of numerous factors, including location on the proximal aspect of folds or flexures, where they may be difficult to detect with the forward-viewing colonoscope.

The Third Eye Retroscope (TER) is a disposable device that is passed through the instrument channel of a standard colonoscope to provide a retrograde view that complements the forward view of the colonoscope during withdrawal.

Dr Daniel DeMarco and colleagues from Texas, USA evaluated whether experience with the Third Eye Retroscope affects polyp detection rates and procedure times in experienced endoscopists who had not previously used the equipment.

Additional detection rates with the Third Eye Retroscope were 25% for adenomas

Gastrointestinal Endoscopy

The team performed an open-label, prospective, multicenter study at 9 U.S. sites, involving 298 patients presenting for colonoscopy, evaluating the use of the TER in combination with a standard colonoscope.

After cecal intubation, the Third Eye Retroscope was inserted through the instrument channel of the colonoscope.

During withdrawal, the forward and retrograde video images were observed simultaneously on a wide-screen monitor.

The team's primary outcome measures were the number and size of adenomas and all polyps detected with the standard colonoscope and with the colonoscope combined with the Third Eye Retroscope.

Secondary outcome measures were withdrawal phase time and total procedure time.

Each endoscopist examined 20 subjects, divided into quartiles according to the order of their procedures, and results were compared among quartiles.

Overall, 182 polyps were detected with the colonoscope and 27 additional polyps with the Third Eye Retroscope, a 15% increase.

A total of 100 adenomas were detected with the colonoscope and 16 more with the Third Eye Retroscope, a 16% increase.

For procedures performed after each endoscopist had completed 15 procedures while using the Third Eye Retroscope, the mean additional detection rates with the Third Eye Retroscope were 17% for all polyps and 25% for adenomas.

The research team found that for lesions 6 mm or larger, the overall additional detection rates with the Third Eye Retroscope for all polyps and for adenomas were 23% and 24%, respectively.

For lesions 10 mm or larger, the overall additional detection rates with the Third Eye Retroscope for all polyps and for adenomas were 23% and 19%, respectively.

The team noted that the mean withdrawal times in the first and fourth quartiles were 11 and 9 minutes, respectively.

Dr DeMarco's team concludes, "Polyp detection rates improved significantly with the TER, especially after 15 procedures, when the mean additional detection rate for adenomas was 25%."

"Additional detection rates with the Third Eye Retroscope for medium-size and large adenomas were greater than for smaller lesions."

"These results suggest that, compared with a colonoscope alone, a retrograde-viewing device can increase detection rates for clinically significant adenomas without detriment to procedure time or procedure complications."