Background and study aims: Endoscopic screening with polypectomy reduces colorectal cancer (CRC) incidence. Incomplete polyp removal may attenuate the effect of screening. This randomized trial compared cold snare polypectomy (CSP) with hot snare polypectomy (HSP) regarding complete polyp resection. Patients and methods: We included patients ≥ 40 years at 8 hospitals in 4 countries who had at least one 4-9 mm non-pedunculated polyp detected at colonoscopy. Patients were randomized 1:1 to CSP or HSP. Biopsies from the resection margins were obtained systematically after polypectomy in both groups. We hypothesized that CSP would be non-inferior to HSP with a non-inferiority margin of 5%. Logistic regression models were fitted to identify factors explaining incomplete resection. Results: In total, 425 patients, with 608 polyps were randomized to either CSP or HSP. Of 318 polyps removed by CSP and 283 polyps removed by HSP, 34 (10.7%) and 21 (7.4%) were incompletely resected, respectively, with an adjusted risk difference of 3.2% (95% CI -1.4 – 7.8). There was no difference between the groups in terms of post-polypectomy bleeding, perforation, or abdominal pain. Independent risk factors for incomplete removal were serrated, odds ratio (OR) 3.96, (95% CI 1.63-9.66) and hyperplastic histology, OR 2.52 (95% CI 1.30-4.86)) in adjusted analyses. Conclusion: In this randomized trial, non-inferiority for cold snare polypectomy could not be demonstrated. Polyps with serrated histology are more prone to incomplete resection compared to adenomas. Cold snare polypectomy for small polyps can be used safely in routine colonoscopy practise.

Background Endoscopic screening with polypectomy has been shown to reduce colorectal cancer incidence in randomized trials. Incomplete polyp removal and subsequent development of post-colonoscopy cancers may attenuate the effect of screening. This study aimed to quantify the extent of incomplete polyp removal. Methods We included patients aged 50–75 years with nonpedunculated polyps ≥ 5 mm removed during colonoscopy at four hospitals in Norway. To evaluate completeness of polyp removal, biopsies from the resection margins were obtained after polypectomy. Logistic regression models were fitted to identify factors explaining incomplete resection. Results 246 patients with 339 polyps underwent polypectomy between January 2015 and June 2017. A total of 12 polyps were excluded due to biopsy electrocautery damage, and 327 polyps in 246 patients (mean age 67 years [range 42–83]; 52 % male) were included in the analysis. Overall, 54 polyps (15.9 %) in 54 patients were incompletely resected. Histological diagnosis of the polyp (sessile serrated lesions vs. adenoma, odds ratio [OR] 10.9, 95 % confidence interval [CI] 3.9–30.1) and polyp location (proximal vs. distal colon, OR 2.8, 95 %CI 1.0–7.7) were independent risk factors for incomplete removal of polyps 5–19 mm. Board-certified endoscopists were not associated with lower rates of incomplete resection compared with trainees (14.0 % vs. 14.2 %), OR 1.0 (95 %CI 0.5–2.1). Conclusion Incomplete polyp resection was frequent after polypectomy in routine clinical practice. Serrated histology and proximal location were independent risk factors for incomplete resection. The performance of board-certified gastroenterologists was not superior to that of trainees.

In this exploratory study, there was little variation on important colonoscopy quality indicators between endoscopy assistants. However, there were differences among assistants that may be clinically important. Endoscopy assistants should be subject to quality surveillance similarly to endoscopists.