San Diego—A novel balloon-assisted colonoscope appears to substantially improve polyp and adenoma detection rates (ADRs) by flattening out colonic folds and making it easier for the endoscopist to detect previously hidden polyps and adenomas.

“As we all know, we miss up to 28% of polyps and anywhere from 12% to 24% of adenomas, and there are many reasons for this,” said investigator Seth Gross, MD, citing location behind proximal folds, lesions in the right colon, poor colonoscopic technique and subpar bowel preparations among the reasons.

In recent years, industry has been hard at work to improve the detection of polyps and adenomas, especially on the back sides of colonic folds. Advances in endoscopic techniques have included the Third Eye Retroscope, FUSE Full Spectrum Endoscopy, OmniVision, the Endocuff, cap-assisted colonoscopy and the subject of the study by Dr. Gross and his colleagues, the balloon-assisted G-Eye colonoscope.

Key features of the G-Eye colonoscope, which is approved for use in the European Union and is awaiting FDA approval in the United States, include “straightening of colonic folds, smoothing of colonic topography, preventing endoscopic slippage and centralizing optics. This allows you to visualize polyps right in front of you,” Dr. Gross explained.

The platform consists of a regular video processor and colonoscope, which is fitted with a permanently integrated and reusable balloon, Dr. Gross said. The balloon is inflated after the endoscopist reaches the cecum, and remains inflated throughout the withdrawal portion of the procedure.

Dr. Gross and his colleagues conducted a multicenter, tandem trial designed to compare G-Eye colonoscopy with standard colonoscopy. They randomized 106 patients to one of two groups: 54 patients in group A underwent standard colonoscopy followed by G-eye colonoscopy, and 52 patients in group B underwent the procedures in the opposite order.

“Our study end points were polyp and adenoma detection, G-Eye additional polyp and adenoma detection rate, G-Eye polyp and adenoma miss rate, and other things such as insertion, withdrawal and total procedure times,” Dr. Gross said.

Total procedure time with standard colonoscopy was 11 minutes, with insertion averaging 5.2 minutes and withdrawal averaging 4.8 minutes. With G-Eye colonoscopy, total procedure time was 13 minutes, with insertion taking 5.1 minutes and withdrawal 5.6 minutes. No adverse events occurred in either study group.

In group A, when G-Eye colonoscopy followed standard colonoscopy, users of the balloon-assisted device detected twice the number of polyps.

“Of note, eight new patients were found to have polyps,” Dr. Gross said.

In group B, the initial colonoscopy conducted with G-Eye colonoscopy revealed 51 polyps in 28 patients, whereas the standard procedure found three polyps in two patients, suggesting a polyp miss rate of 5.6% for G-Eye colonoscopy.

For adenoma detection, standard colonoscopy in group A identified 21 adenomas in 14 patients; the subsequent G-Eye procedure detected 17 additional adenomas in three new patients, for an additional ADR of 81%. In group B, G-Eye colonoscopy identified 37 adenomas in 21 patients, whereas standard colonoscopy found three adenomas in two patients, giving the G-Eye an adenoma miss rate of 7.5%.

In the ascending colon, detection rates for polyps and adenomas with G-Eye colonoscopy were 35% and 41%, respectively, compared with 10% and 14%, respectively, for standard colonoscopy. G-Eye’s miss rate in the ascending colon was 5.6% for polyps and 7.5% for adenomas, compared with a miss rate of 50% and 44.7%, respectively, with standard colonoscopy.

The finding of additional adenomas resulted in shorter surveillance intervals in patients whose adenomas were not detected by initial standard colonoscopy.

“In terms of [polyp] size, when standard colonoscopy went first, the G-Eye picked up larger polyps and standard colonoscopy missed polyps between 5 mm and 10 mm,” Dr. Gross said. “When G-Eye went first, it did miss some polyps, but only smaller ones, less than 5 mm. There were no larger lesions missed.”

The researchers concluded that the use of G-Eye colonoscopy identified significantly more polyps and adenomas, and is associated with a much lower miss rate, compared with standard colonoscopy. A large randomized trial is being conducted.

Amit Rastogi, MD, one of the moderators of the plenary session where Dr. Gross presented his study, noted that missed adenomas continues to be a major limitation of colonoscopy, and, aside from poor withdrawal technique, is largely due to the topography of the human colon.

“Polyps can hide on the proximal aspect of the colonic folds and evade detection by even the most skilled colonoscopist,” said Dr. Rastogi, director of endoscopy at Kansas City Veterans Affairs Medical Center, in Missouri, and associate professor of medicine at the University of Kansas, Kansas City.

“This study by Gross et al is encouraging and has shown that the balloon colonoscope misses fewer polyps and adenomas compared with standard colonoscopy by its ability to flatten the colonic folds. It appears to be a simple technique that will not require much training or experience to implement in practice,” he said.

“However,” he added, “we need larger studies with multiple investigators to make definitive conclusions of its superiority, and before it can stake a claim to replace standard colonoscopy. Other issues, such as financial implications, also will need to be addressed.”


Drs. Gross and Rastogi reported no relevant conflicts of interest.