Cold snare polypectomy (CSP) may eliminate the risk of perforation and cannot lead to the post-polypectomy syndrome that is associated with traditional, or hot snare, polypectomy (HSP) involving electrocautery. Extensive research has documented that the risk of bleeding after CSP for subcentimeter polyps is similar or smaller than that after HSP [1]. Meta-analyses have shown that the incomplete resection rate (IRR) is comparable between the two methods, but varies markedly between the studies (0–25 %), with significant heterogeneity [1] [2]. The quality of evidence has been rated as very low. Some of the variation is probably caused by differences in study settings, with the lowest IRRs coming from academic expert centers. Complete resection of colorectal polyps is of obvious importance. It has been estimated that 20 % of post-colonoscopy cancers may be caused by incompletely removed polyps [3].

In this issue of Endoscopy, von Renteln et al. offer another piece of the puzzle regarding the usefulness of the CSP technique [4]. In their single-center prospective cross-sectional study, the authors investigated the IRR of 128 colorectal polyps sized 4–20 mm. The nine endoscopists who participated in the study were all board-certified and had extensive colonoscopy experience. After the removal of all visible polyp tissue, completeness of removal was assessed by biopsies obtained from the resection margins. The IRR was disappointingly high: 18 % of polyps of 4–9 mm and 21 % of polyps of 10–20 mm were not completely removed.

“...we need to fully acknowledge the inter-endoscopist variation in complete resection rate that probably exists in most centers, even among those who are considered experts.”

There are obvious limitations in this study: the sample size was small, the endoscopists’ experience with CSP was limited, and it is unclear how, or whether any, CSP training was performed prior to the study. The manuscript does however provide some important information and points toward quality challenges that should be acknowledged. First, incomplete resection of colorectal polyps represents a problem; even resection of subcentimeter polyps may be difficult in everyday practice. Second, the polyp removal technique may be a separate quality metric that is not captured by the list of quality indicators currently recommended by the ESGE [5]. Interestingly, the IRR was not associated with the key quality indicators adenoma detection rate, cecal intubation rate, or withdrawal time. The IRR should be validated and monitored. Third, the IRR was strikingly different for serrated polyps (26 %) compared with adenomas (16 %), even if such differences were not statistically significant. This difference has also been reported by others [6] [7]. Finally, in this study, as in numerous other studies of colonoscopy quality, the inter-endoscopist variation is large. Too large.

So, where do we go from here? First, we still need more data. The cold snare revolution is already here: cold snaring is recommended by the ESGE as the method of choice for the removal of polyps < 10 mm and is also gaining increasing interest for the removal of larger polyps. However, the data from von Renteln and others show that we have a way to go to improve our polypectomy service. It is still unknown which technique is optimal, even for the removal of small polyps [2]. Underwater endoscopic mucosal resection (EMR) and traditional EMR have shown promising results, but data comparing these methods are still limited [2]. There are also scarce data on CSP for polyps > 10 mm. Importantly, reports from routine clinical practice, like the present report from von Renteln, remind us that the extrapolation of findings from expert hands into everyday use may not be without problems.

Second, we need to know how we should teach, or assess competence in, our endoscopists. Presently, the Direct Observation of Polypectomy Skills questionnaire (DOPyS) is the only tool to assess polypectomy competence, and studies on how to achieve competence are limited [8]. One study failed to show any improvement in polypectomy skills among trainees after attending lectures given by experienced endoscopists [9]. Another study found that the DOPyS score improved after feedback and the use of educational videos, but the scores improved for small polyps only and it is unclear how the DOPyS score actually relates to incomplete polyp resection [10].

Finally, we need to fully acknowledge the inter-endoscopist variation that probably exists in most centers, even among those who are considered experts. To reduce this variation, endoscopy units first have to show its existence. This is the responsibility of the leader. In the assessment of incomplete polyp resection, obtaining margin biopsies after polypectomy from a limited number of procedures and for each endoscopist may provide a benchmark for further quality improvement. It can be painful for experienced endoscopists who may feel that their competence is questioned but, at the end of the day, quality is about the patient, not the endoscopist. And the good thing is that, if unwanted variation is indeed found, a very competent colleague has probably been identified in the endoscopy unit and can serve as teacher for others.

Article published online:
24 February 2023

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