Cap, hood, cuff, and balloon – what next for colonoscopy?

We read with great interest the paper by Gralnek et al. [1] on the use of balloon colonoscopy. This is yet another invention that aims to improve the adenoma detection rate (ADR) during colonoscopy. We would like to make a few comments about the paper.

We would like to point out that the study population was enriched and does not represent the ‘all comers’ encountered in day-to-day practice. The included participants were referred for polyp surveillance and colorectal cancer screening along with others who were referred for diagnostic colonoscopy. The authors did not provide a breakdown of the numbers for each referral type and we believe the polyp burden in the chosen population would be expected to be high, accounting for the high polyp detection rate reported in the study (53.2 %). The authors reported a cecal intubation rate of 100 % (47/47); however, 3 out of 50 patients enrolled initially, were rejected for various reasons (technical problem, hernia, and poor bowel preparation) and were not included in the final analysis. Participants with diverticular disease, inflammatory bowel disease, and suspected strictures were also excluded. This highly selected nature of the study group, far removed from everyday clinical practice, might possibly explain the impressive mean cecal intubation time of 4.3 minutes (standard deviation 2.4 minutes).

Secondly, there was no control group in the study, which raises the question of whether a comparable polyp/adenoma detection rate might have been achieved with other means such as use of a conventional endoscope with slow withdrawal over a 7 – 8-minute period. The use of either tandem colonoscopies or a crossover trial to investigate the adenoma miss rate would have been the preferred design for this study.

Furthermore, it was unclear as to why terminal ileal intubation was successful in only 5 of 47 colonoscopies and rectal retroversion in only 31 of 47 colonoscopies. There was no comment on whether the integral balloon at the bending portion of the colonoscope impairs the maneuverability of the tip. If this were so, it would pose serious questions about tip control when using balloon colonoscopy.

Interim results from a randomized controlled tandem study comparing standard colonoscopy with balloon colonoscopy were presented at the UEG Week in Berlin in 2013 [2]. The results were impressive, with 100 % additional detection of polyps with second-pass balloon colonoscopy and a 5.6 % polyp miss rate on first-pass balloon colonoscopy. The final report is still awaited; however, future research into balloon colonoscopy, with regard to detection of right-sided adenomas and to tip control for difficult polypectomy, would be interesting.

• References

• 1 Gralnek IM, Suissa A, Domanov S. Safety and efficacy of a novel balloon colonoscope: a prospective cohort study. Endoscopy 2014; 46: 883-887
• 2 Shpak B, Halpern Z, Kiesslich R et al. A novel balloon-colonoscope for increased polyp detection rate – intermediate results of a randomized tandem study. United European Gastroenterology Week (UEGW); 2013 Oct 12–16; Berlin, Germany. Available at: https://www.ueg.eu/education/document-detail/?file=102056 Accessed: 2014 Nov 27