2020 Volume 62 Issue 3 Pages 364-370
Background and aim: Cold snare polypectomy (CSP) is a safe and easy procedure that has recently become widely performed for resecting small colorectal polyps. However, the polyps are sometimes unexpectedly polyps with advanced neoplasia. It is thus important to evaluate both the horizontal and vertical margins of resection. Here, we retrospectively investigated the resection depth of CSP.
Methods: We examined 503 small colorectal polyps that were resected by CSP between August 2017 and July 2018. We histologically evaluated the resected layers, and divided the samples into two groups according to the histological resection depth: the M group included samples whose resection depth reached the mucous membrane, and the S group included samples whose resection depth reached the muscularis mucosa or submucosa. We performed a comparative review of the size, location, horizontal margin, appearance of the cut surface of endoscopic resection, and inter-operator variations between the two groups.
Results: The resected layers varied among the samples: the resection depth reached the mucous membrane in 274 samples (55%), reached the muscularis mucosa in 193 samples (38%), and reached the submucosa in 36 samples (7%). The size, appearance of the cut surface of endoscopic resection, and inter-operator variations did not differ significantly between the M and S groups. In contrast, the location of the polyps differed significantly between the two groups, with the cecum more prevalent in the M group and the rectum more prevalent in the S group. Also, excluding the 106 samples that had an unclear horizontal margin, the negative horizontal margin rate was significantly higher in the S group (109/173; 63%) than in the M group (85/224; 28%).
Conclusions: The resection depth differed according to the location of the polyp, with the cecum more prevalent in the M group and the rectum more prevalent in the S group. The S group was more likely to have a negative horizontal margin. However, the resection depth achieved with CSP reached the muscularis mucosa in less than half of the cases. Given the inconsistency of resection depth, indication of CSP should be carefully decided as for larger tumor diameter.
