Introduction
According to updated guidelines, non-pedunculated polyps of small size are resected with a cold snare in air dilated intestinal lumen(Conventional Cold Snare Polypectomy-CCSP) [1]. R0 resection rate(R0-RR) using CCSP ranges from 32.9% to 96.6%[2-5] while meta-analyses showed that the incomplete resection rate (IRR) after CCSP was 17.3% [6], highlighting the need for further research regarding the most suitable polypectomy method for small polyps. Recently, several studies have described the benefits of water-aided colonoscopy, as well as safety and efficacy of underwater polypectomy in large colon polyps. However, data on small polyps which are the most commonly diagnosed, are insufficient. In response to this gap in the literature, we conducted the first randomized, double-blind, controlled trial to compare underwater cold snare polypectomy(UCSP) to CCSP for non-pedunculated colon polyps of size 5-10mm.
Aims & Methods
The CCSP procedure involved: opening of the intestinal lumen using air/CO2, snaring of the lesion and surrounding healthy tissue, and excision. On the other, UCSP involved three more steps before snaring of the polyp: complete suction of air, partial opening of the intestinal lumen using sterile water, complete immersion of the lesion in water. In order to determine the IRR, additional biopsies were taken from the horizontal margins of the resection site. All polypectomy–related complications were recorded. The objective of the study was to compare the safety and efficacy between UCSP and CCSP regarding resection of non-pedunculated colon polyps with size 5-10mm. Primary outcome was the investigation of the difference in the rate of area containing muscularis mucosa between the two polypectomy techniques. The secondary outcomes focused on differences in R0-RR, IRR, en-bloc resection, and complications. Patients were allocated with a 1:1 ration to UCSP or CCSP group.If more than one polyp was diagnosed in a patient, then all were resected by the same method. The randomization process was done by using the random numbers method of Microsoft Excel 2016. Both pathologists and patients were blinded.
Results
Between March 2021 and December 2022, a total of 229 patients were enrolled in the study, with 397 polyps(UCSP:198, CCSP:199) included in the per protocol analysis. Results demonstrated that UCSP was superior to CCSP in terms of both muscularis mucosa resection rate (81.72% vs. 72.33%, p=0.003) and IRR (8.5% vs. 3.5%, p=0.05). However, the R0-RR did not differ significantly between the two groups (UCSP: 93.9%, CCSP: 90%, p=0.29). UCSP also achieved a higher rate of en bloc resections than CCSP(98% vs 93.5%, p=0.04). The only complication observed was non-severe intraprocedural bleeding, which was successfully managed during endoscopy(UCSP 0.5%, CCSP 2%, p=0.37). Expert endoscopists in CCSP achieved a higher R0-RR than non-experts (93% vs. 84%, p=0.05), whereas no significant difference in R0 resection rate was observed among different levels of expertise in UCSP. Polyp histology and size were found to affect R0 resection rates in both groups, with serrated histology and sizes of 8-10mm linked to lower R0 resection rates.
Conclusion
UCSP is a safe technique that achieves better results in the resection of muscularis mucosa and is associated with a lower IRR than CCSP, thus reducing the risk of residual or recurrent lesions. Furthermore, the efficacy of UCSP does not depend on the endoscopist's expertise and thus could be the optimal approach for young or inexperienced gastroenterologists.
References
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