To cuff or not to cuff: that is the question!

Colonoscopy is the gold standard test for detection and removal of early colorectal neoplasia. Despite modern advances in endoscope resolution, bowel preparation, and a focus on endoscopist technique, colonoscopy can miss precancerous polyps. Miss rates for small adenomas exceed one in four, and adenoma detection rates (ADRs) vary widely between providers, directly impacting our patients’ risk of interval colon cancer and death [1] [2].

At the crux of the problem is the fact that examining every square inch of the colon, even under ideal circumstances, is challenging. Much of the mucosa lies behind haustral folds, evading easy inspection. Furthermore, colonoscopy does not proceed at a uniform pace, as redundancy, loops, and angulations affect the rate of passage of mucosa across the field of view.

A variety of colonoscopy enhancements have been devised in an attempt to address these anatomical constraints and improve adenoma detection. These include wide-angle and retrograde viewing platforms, image enhancement systems, and add-on devices fitted to the shaft or tip of the colonoscope to stabilize and retract the mucosa during withdrawal. Despite intense interest from physicians and industry, few enhancements have entered the mainstream of routine clinical practice.

The current issue of Endoscopy reports the results of three independent prospective trials evaluating the effectiveness of one approach – cuff-assisted colonoscopy – for adenoma detection compared with standard colonoscopy. These studies assess the endocuff device (Endocuff; Arc Medical Design Ltd., Leeds, UK) under varied settings. Together, these studies add to the growing body of evidence suggesting that endocuff-assisted colonoscopy can improve adenoma detection, but that the maximal benefit is seen in settings where the ADR is lower to begin with, that is, where there is the most ground to gain.

The endocuff consists of a disposable polymer sleeve, which is placed over the tip of the colonoscope and carries finger-like radial projections that are designed to impinge upon and flatten the mucosa upon withdrawal. The device has undergone two iterations: a first-generation sleeve with two rows of fingers, and a second-generation device (Endocuff Vision) with a single row of longer projections. The first-generation device has been evaluated in several prospective randomized trials, with mixed results. One study of over 1000 symptomatic individuals with positive fecal immunochemical tests found no difference in the ADR between endocuff and standard colonoscopy (52 % in each case) [3]. Another study, in a lower-risk group of screening, surveillance, and diagnostic procedures, found a significantly higher ADR when using the endocuff (35 % vs. 21 %; P < 0.01) [4]. These divergent results reflect the fact that the impact of the device appears to depend on the baseline ADR.

“It appears that the endocuff facilitates a more thorough examination, positively impacting both the insertion and withdrawal phases of colonoscopy. However, there may be modest gains from the addition of an adjunctive device for endoscopists with a high ADR (as might be the case with higher pretest probability populations) and conduct thorough and lengthy inspections.”

Gonzalez-Fernandez et al. [5] evaluated the first-generation endocuff in a population at low baseline risk of adenoma: Latin American adults undergoing screening colonoscopy, with a significant female predominance. All cases involved trainee endoscopists under expert supervision, and none had received prior training with the device. Use of the endocuff was associated with a significantly higher ADR than conventional colonoscopy, although ADR in both arms was low by Western standards (22.4 % vs. 13.5 %; P = 0.02). The authors note that the low adenoma prevalence is similar to other reports from Latin America and likely reflects the source population.

In contrast, Bhattacharyya et al. [6] studied a population in the United Kingdom that had a much higher prevalence of adenomas, randomizing 534 predominantly male patients with positive fecal occult blood tests to colonoscopy using either the second-generation endocuff device or conventional colonoscopy. Endoscopists involved in the study were highly experienced and were selected for inclusion based on their high ADRs. All had some experience with the device (at least 15 procedures). ADR was uniformly high and did not differ between the endocuff and standard groups (63.0 % vs. 60.9 %). Notably, withdrawal times were almost twice as long in this study than in the former study, averaging 19.5 minutes in the standard arm. The authors do note that there was a small decrease in withdrawal time with use of the endocuff (16.9 vs. 19.5 minutes) without a detrimental effect on ADR, but it is doubtful whether such a difference is meaningful enough to justify its use in this setting.

Finally, Triantafyllou et al. [7] took a different approach and conducted a tandem colonoscopy study, focussing on missed rather than found adenomas. In this well-designed, multicenter, crossover trial, patients were randomized to undergo same-day back-to-back colonoscopy, with either conventional colonoscopy followed by endocuff-assisted colonoscopy or vice versa. The primary outcome was the adenoma miss rate. Endoscopists were selected to have baseline ADRs of over 35 %, and had performed at least 10 endocuff procedures. The adenoma miss rate was significantly lower in those who underwent endocuff-assisted colonoscopy (14.7 % vs. 38.4 %; P < 0.01). The difference in miss rates was particularly pronounced in the proximal colon (10.4 % vs. 38.9 %), but did not extend to those with advanced adenomas and sessile serrated adenomas, suggesting that the benefit of the endocuff is largely limited to small adenomas.

What lessons can we learn from these three trials? Use of the endocuff appears to be safe and does not significantly prolong insertion or withdrawal times, but potentially shortens the examination. There is no discernible learning curve for its use. A small proportion of patients in each study (ranging from 1 % to 6 %) required removal of the endocuff in order to complete the colonoscopy, largely owing to difficulty navigating tortuous segments of the sigmoid with the cap in situ. The device does improve adenoma detection, but its impact wanes as baseline endoscopists’ ADR increases. It appears that the endocuff facilitates a more thorough examination, positively impacting both the insertion and withdrawal phases of colonoscopy. However, there may be modest gains from the addition of an adjunctive device for endoscopists with a high ADR (as might be the case with higher pretest probability populations) and conduct thorough and lengthy inspections.

Given the emergence of several less-invasive alternatives to colonoscopy as a screening modality for colorectal cancer, endoscopists are under greater pressure to improve quality and limit variability to remain competitive. The endocuff may represent a reasonable strategy for low ADR populations and providers who are seeking to raise the bar.

• References

• 1 Corley DA, Jensen CD, Marks AR. et al. Adenoma detection rate and risk of colorectal cancer and death. N Engl J Med 2014; 370: 1298-1306
• 2 Van Rijn JC, Reitsma JB, Stoker J. et al. Polyp miss rate determined by tandem colonoscopy: a systematic review. Am J Gastroenterol 2006; 101: 343-350
• 3 Van Doorn SC, van der Vlugt M, Depla A. et al. Adenoma detection with Endocuff colonoscopy versus conventional colonoscopy: a multicentre randomised controlled trial. Gut 2017; 66: 438-445
• 4 Floer M, Biecker E, Fitzlaff R. et al. Higher adenoma detection rates with endocuff-assisted colonoscopy – a randomized controlled multicenter trial. PLoS One 2014; 9: e114267
• 5 Gonzalez-Fernandez C, García-Rangel D, Aguilar-Olivos NE. et al. Higher adenoma detection rate with the endocuff: a randomized trial. Endoscopy 2017; 49: 1061-1068
• 6 Bhattacharyya R, Chedgy F, Kandiah K. et al. Endocuff-assisted vs. standard colonoscopy in the fecal occult blood test-based UK Bowel Cancer Screening Programme (E-cap study): a randomized trial. Endoscopy 2017; 49: 1043-1050
• 7 Triantafyllou K, Polymeros D, Apostolopoulos P. et al. Endocuff-assisted colonoscopy is associated with a lower adenoma miss rate: a multicenter randomized tandem study. Endoscopy 2017; 49: 1051-1060