Authors Maria Zachou, Martha Nifora, Theodoros Androutsakos, Georgios Katsaras, Konstantinos Varytimiadis, Christina Zoumpouli, Panayiotis Karantanos, Efthimia Lalla, Georgios Mpetsios, Maria Panoutsakou, Roxana Stoica, Dionisia Thermou, Georgios Mavrogenis, Evangelia Dikoudi, Nikolaos Nikiteas, Stavros Sougioultzis, Evangelos Kalaitzakis, Stilianos Kykalos.

Background The wide range of R0 resection rates (R0RR) and incomplete resection rates (IRR) observed with conventional cold snare polypectomy (CCSP) emphasizes the necessity for technique enhancement. The COLDWATER study aimed to compare underwater cold snare polypectomy (UCSP) to CCSP for 5-10-mm colorectal polyps, focusing on comprehensive histopathological evaluation, efficacy, and safety.

Methods This was a randomized, single-blind, controlled trial comparing UCSP to CCSP for nonpedunculated colorectal polyps of size 5-10 mm. The primary outcome was to report differences in the muscularis mucosa resection ratio. The secondary outcomes focused on differences in depth of excision, R0-RR, IRR, en bloc resection rate, adverse events, and recurrence rate.

Results The COLDWATER study found higher muscularis mucosa resection in UCSP (81.72±62.81% vs. CCSP: 72.33±22.33%, P=0.003) with comparable submucosa presence (UCSP: 16.6%, CCSP: 12.5%, P=0.25). UCSP showed better outcomes regarding IRR (3.5% vs. 8.5%, P=0.05) and en bloc resection (98% vs. 93.5%, P=0.04). In CCSP, expert endoscopists achieved higher R0RR than nonexperts, while UCSP showed no significant difference in R0RR across endoscopist’s experience levels.

Conclusions UCSP achieves a more extensive excision of the muscularis mucosa compared to CCSP, even though it does not attain a deeper excision. Additionally, UCSP shows a higher en bloc resection rate, with lower rates of IRR, and emerges as a promising technique for training inexperienced endoscopists in polypectomy, given its experience-independent success in achieving R0 resection.

Keywords Underwater cold snare polypectomy, underwater polypectomy, conventional cold snare polypectomy, muscularis mucosa resection ratio

Ann Gastroenterol 2024; 37 (4): 466-475