Cold snare polypectomy: is there a limit to polyp size?Referring to Papastergiou V et al. p. 403–411 and Tate DJ et al. DOI: 10.1055/s-0043-121219
27 March 2018 (online)
Cold snare polypectomy (CSP) is an established technique for diminutive (1 – 5 mm) colorectal polyps and is recommended in current endoscopy guidelines . Cold techniques avoid the risk of colonic mural thermal injury that can lead to post-polypectomy syndrome, perforation or delayed bleeding.
However, what about lesions > 5 mm in size? For small polyps (6 – 9 mm), evidence supporting cold snaring is limited and guideline recommendations are not definitive . Few studies have compared hot snare polypectomy (HSP) with CSP for small (6 – 9 mm) polyps, and suggest that cold snare efficacy is size dependent. Kawamura et al. assessed 687 polyps in a multicenter randomized study of HSP vs. CSP for polyps 6 – 9 mm . Injection was performed before 43 % of HSPs, but not before CSP. CSP had a shorter median procedure time, and noninferiority was confirmed from biopsy of the polypectomy defect margins. Zhang et al. studied 525 small polyps randomized to either HSP with injection or CSP without injection . The polypectomy defect margin and base biopsies showed higher rates of incomplete resection with CSP (8.5 %) vs. HSP (1.5 %).
In this issue of Endoscopy, Papastergiou et al. report a randomized trial of the noninferiority of cold snare endoscopic mucosal resection (EMR) to hot snare EMR for nonpedunculated polyps 6 – 10 mm in size . A total of 164 polyps in 155 patients were studied, with the primary end point being complete resection assessed histologically with both quadrantic margin biopsies and a single base biopsy. Complete resection rates with cold snare EMR (92.8 %) were noninferior to hot snare EMR (96.3 %).
Unlike standard cold snare polypectomy, the technique in this study employed submucosal injection of normal saline prior to polypectomy in both hot and cold arms. This permits more precise assessment of the role of electrocautery than other studies, where injection was performed for HSP but not for CSP  . The data from the Papastergiou et al. study indicate that electrocautery does not appear to be necessary for lesions 6 – 10 mm, at least when submucosal injection is performed.
“With further evolution of cold resection techniques, electrocautery may not be required, even for larger lesions.”
However, practicing endoscopists may question the role and requirement of universal submucosal injection for lesions of 6 – 10 mm, and this should be the focus of further research. Although submucosal injection was previously reserved for large lesions, it seems that endoscopists may be increasingly using submucosal injection even for HSP of small polyps given the risks of thermal therapy. The need for routine injection for cold snaring of this size requires critical evaluation, as cost and time barriers may be disincentives to its widespread adoption. Injection adds significantly to the procedure cost, directly via the need for an injector and for injectate, and indirectly via increased procedure time. Time savings have been previously demonstrated for cold snaring without injection for polyps 3 – 8 mm when compared with hot snaring with or without submucosal injection  .
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