The “Cold Revolution” – cold snare resection of sessile colorectal polyps

In recent years, the use of cold snare polypectomy (CSP) for sessile colorectal polyps less than 10 mm in size has gained widespread popularity. Dedicated cold snares that facilitate endoscopic resection are now widely available. CSP is easy and quick to perform with no need for submucosal injection. CSP avoids potential complications related to the use of electrocautery. Unlike thick-stalked pedunculated polyps and large sessile polyps, which are supplied by larger blood vessels, small non-pedunculated or flat lesions less than 10 mm in size are not supplied by such vessels, so the need to use electrocoagulation to prevent immediate severe bleeding after endoscopic resection is less of a concern. The European Society of Gastrointestinal Endoscopy (ESGE) Clinical Guideline suggests the use of CSP for sessile polyps of 6–9 mm in size because of its safety profile [1]. The time interval for surveillance colonoscopy is based on the assumption that complete endoscopic resection of the detected adenomas will have been achieved. Incomplete resection of colorectal adenomas is an important cause of post-colonoscopy colorectal cancer [2]. There is uncertainty about the relative efficacy of CSP compared with hot snare polypectomy (HSP), and also about the generalizability of the currently published outcome data to more diverse patient populations and endoscopy practice settings [3].

“Limiting the size of a target lesion to less than 10 mm allows for en bloc resection when using CSP. Larger lesions would require piecemeal resection with CSP, unlike for hot snare EMR, which can achieve en bloc resection for lesions up to 20 mm in size.”

In this issue of Endoscopy, Pedersen et al. reported the results of an international multicenter randomized trial, involving centers from Norway, Poland, Denmark, and the USA, that compared CSP with HSP for colorectal polyps of 4–9 mm in size. The primary outcome of interest was the incomplete resection rate (IRR) [4]. A total of 425 patients with 608 polyps were randomized to either CSP or HSP, and the IRRs were 10.7 % and 7.4 %, respectively, with an adjusted risk difference of 3.2 % (95 %CI −1.4 % to 7.8 %). There was no difference between the two groups in terms of procedure-related complications. Subgroup analyses revealed that the risk of incomplete resection was substantially larger for sessile serrated lesions (SSLs) and hyperplastic polyps compared with adenomas. Although non-inferiority, defined as within a limit of 5 % in favor of HSP, could not be established, ultimately the difference between CSP and HSP, whether as a group, or stratified by histology, was small. The key strengths of the study were that it was a multicenter study and well designed. These results further affirm the generalizability of the use of CSP for the resection of subcentimeter colorectal polyps to a wider population.

An important issue to consider is whether the complete resection rate with CSP can be further optimized. A systematic review with meta-analysis published in 2018 reported that both CSP and HSP had similar IRRs of 6 % and 5 %, respectively [3]. More recently, de Benito Sanz et al. conducted a Spanish multicenter study of HSP versus CSP for colorectal polyps of 5–9 mm in size and reported an IRR of 7.5 % with CSP and 6 % with HSP [5]. On the other hand, Sidhu et al., while performing a multicenter study to compare the use of thin- and thick-wire snares for CSP in small (≤ 10 mm) colorectal polyps, reported that the overall IRR of the cohort was only 1.5 %. There was no significant difference in the IRR between the thin- and thick-wire arms [6].

The learning curve for CSP is not steep, so gaining mastery of the technique is not difficult. What is important for endoscopists is to be mindful of the finer aspects of the CSP technique. These details include the following: (i) careful ascertainment of the lateral margins, especially for a flat lesion, including the use of image-enhanced endoscopy if necessary; (ii) ensuring that a 2-mm rim of normal mucosa is captured consistently prior to resection; (iii) maximization of snare pressure on the mucosal surface by applying firm downward pressure on the mucosa with the snare using the up/down wheel of the endoscope; (iv) slow closure of the snare to ensure adequate seating of the snare into the normal mucosa surrounding the polyp, in order avoid the snare slipping over the normal mucosa upon completion of snare closure; (v) careful examination of the mucosal defect and its edges post-resection to detect any residual lesions and allow repeated resection until complete endoscopic resection is achieved [6].

Another relevant question to consider is whether CSP can be extended to lesions larger than 10 mm safely and effectively. In this context, one must be aware of the shallow cutting plane of CSP, and also consider the need for en bloc resection. For instance, a randomized trial reported that submucosal tissue was obtained significantly more frequently with HSP than with CSP (81 % [95 %CI 63 %–92 %] vs. 24 % [95 %CI 11 %–43 %]; P < 0.001) [7]. Limiting the size of a target lesion to less than 10 mm allows for en bloc resection when using CSP. Larger lesions would require piecemeal resection with CSP, unlike for hot snare endoscopic mucosal resection (EMR), which can achieve en bloc resection for lesions up to 20 mm in size. Limited data suggest that large SSLs may be suitable for piecemeal CSP [8]. However, SSLs with endoscopic suspicion of dysplasia and non-pedunculated adenomas with endoscopic features suggestive of high grade dysplasia, intramucosal or superficial submucosal carcinoma should be resected with endoscopic techniques using submucosal injection and electrocautery, such as HSP, EMR, or endoscopic submucosal dissection. This is to ensure adequate lateral and vertical tissue margins are obtained, in order to allow for complete histopathological assessment to determine whether the endoscopic resection is complete and curative.

To conclude, CSP should be embraced globally as one of the first-line techniques for the resection of non-pedunculated colorectal lesions less than 10 mm in size. The efficacy and safety profile of CSP is comparable to traditional HSP. It is possible to minimize the IRR by meticulous attention to the endoscopic technique of CSP. The role of CSP for larger lesions remains undefined. CSP should be avoided when advanced histology is suspected.

Publication History

Article published online:
20 May 2022

• References

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