ObjectiveLarge (≥20 mm) sessile serrated lesions (L-SSL) are premalignant lesions that require endoscopic removal. Endoscopic mucosal resection (EMR) is the existing standard of care but carries some risk of adverse events including clinically significant post-EMR bleeding and deep mural injury (DMI). The respective risk-effectiveness ratio of piecemeal cold snare polypectomy (p-CSP) in L-SSL management is not fully known.DesignConsecutive patients referred for L-SSL management were treated by p-CSP from April 2016 to January 2020 or by conventional EMR in the preceding period between July 2008 and March 2016 at four Australian tertiary centres. Surveillance colonoscopies were conducted at 6 months (SC1) and 18 months (SC2). Outcomes on technical success, adverse events and recurrence were documented prospectively and then compared retrospectively between the subsequent time periods.ResultsA total of 562 L-SSL in 474 patients were evaluated of which 156 L-SSL in 121 patients were treated by p-CSP and 406 L-SSL in 353 patients by EMR. Technical success was equal in both periods (100.0% (n=156) vs 99.0% (n=402)). No adverse events occurred in p-CSP, whereas delayed bleeding and DMI were encountered in 5.1% (n=18) and 3.4% (n=12) of L-SSL treated by EMR, respectively. Recurrence rates following p-CSP were similar to EMR at 4.3% (n=4) versus 4.6% (n=14) and 2.0% (n=1) versus 1.2% (n=3) for surveillance colonoscopy (SC)1 and SC2, respectively.ConclusionsIn a historical comparison on the endoscopic management of L-SSL, p-CSP is technically equally efficacious to EMR but virtually eliminates the risk of delayed bleeding and perforation. p-CSP should therefore be considered as the new standard of care for L-SSL treatment.

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Background and Aims: CSP is standard of care for resecting small (<10mm) colonic polyps. Limited data exist for its efficacy for medium-sized (10-19mm) non-pedunculated polyps, especially conventional adenomas. This study evaluated the effectiveness and safety of CSP/C-EMR for medium-sized non-pedunculated colonic polyps. Methods: A prospective multicentre observational study was conducted between May-2018 and June-2021 of all morphologically suitable 10-19mm non-pedunculated colonic polyps removed by CSP/C-EMR. Once resection was complete, multiple biopsies were taken of the margins circumferentially and centrally. Primary outcome: Incomplete resection rate (IRR) based on residual polyp in these biopsy specimens. Secondary outcomes: Recurrence rate at first surveillance colonoscopy and rates of adverse events. Results: CSP/C-EMR was performed for 350 polyps in 295 patients. Median polyp size: 15mm. 266 (76.0%) Paris 0-IIa classification. Submucosal injection used for 87.1%(n=305) of polyps. Histology:68.5% adenomas, 26.2% SSL without dysplasia, 3.8% SSL with dysplasia and 1.4% hyperplastic. Primary outcome: IRR based on margin or central biopsies being positive was 1.7%(n=6) and 0.3%(n=1) respectively. Secondary outcomes: Polyp recurrence rate was 1.7%(n=4) at first surveillance colonoscopy that was completed for 65.4%(n=229) of polyps at median interval of 9.7 months. Adverse events occurred in 3.4%(n=10) of patients: 1 intraprocedural bleed treated with clips, 3 self-limiting post-polypectomy bleeds, 4 post-polypectomy pain; 2 post-polypectomy-syndrome-like presentations. There were no perforations. Conclusion: CSP/C-EMR for morphologically suitable 10-19mm non-pedunculated colonic polyps is effective and safe, including for conventional adenomas. Rates of incomplete resection and recurrence were low, with few adverse events. Studies directly comparing to hot snare resection are required.