Incomplete resection of 4‒20 mm colorectal polyps when using cold snare and associated factors

Background: Cold snare polypectomy (CSP) is increasingly used for polypectomy and is recommended as first-line modality for small (<10mm) polyps. This study aimed to evaluate incomplete resection rates (IRRs) when using CSP for 4-20mm colorectal polyps. Methods: Adults (45-80y) undergoing screening, surveillance, or diagnostic colonoscopy were included to undergo CSP by nine endoscopists. Primary outcome was IRR for 4-20mm colorectal polyps, defined as presence of polyp tissue in marginal biopsies after resection serrated polyps or adenomas. Secondary outcomes included IRR for serrated polyps, ease of resection and complications. Results: Overall, 413 patients were included (mean age 63; female 48.2%) and 182 polyps 4-20mm were detected and removed by CSP. CSP required conversion to hot snare resection in <1% of polyps <10mm and 44.4% of polyps 10-20mm. IRR for polyps <10mm and ≥10mm was 18.4% and 21.4%. IRR was higher for serrated polyps (25.6%) compared to adenomas (15.7%). IRR was higher for flat (IIa) polyps (OR=2.9, 95% Confidence Interval [CI]=1.13-7.41), when resection was judged as difficult (OR=4.2, 95%CI=1.47-12.13), when piecemeal resection was performed (OR=6.6, 95%CI=1.97-22.01), or when visible residual polyp was present after initial resection (OR=5.4, 95%CI=1.97-14.88). Polyp location, using a dedicated cold snare, or submucosal injection was not associated with incomplete resection. Intraprocedural bleeding requiring endoscopic intervention occurred in 4.7%. Conclusions: CSP for 4-9mm polyps is safe and feasible. However, for lesions ≥10mm, CSP failure occurs frequently, and IRR remains high even after technical success. Incomplete resection was associated with flat polyps, visual residual polyp, piecemeal resection, and difficult polypectomies.