本研究比较了传统和水下内镜粘膜下剥离术 (ESD) 治疗浅表结直肠肿瘤 (SCN) 的手术相关结果。在这项单中心、随机对照试验中，符合日本 ESD 指南指征的 SCN 患者被随机分配接受由专家执行的传统 ESD (CESD) 或水下 ESD (UESD)。主要终点是解剖速度，定义为每次 ESD 时间的标本面积。我们分别分析了 69 例和 70 例 CESD 和 UESD 病例的数据；然而，中位解剖速度没有发现显着差异（分别为 17.4 和 19.9 mm2/min；P = 0.19）。多元回归分析显示，病变与重力方向之间合适的位置关系（合适的PLG；CESD为非重力侧，UESD为重力侧）与解剖速度独立正相关（P < 0.001）。所有病例均实现整块切除，无穿孔。两组之间 ESD 后凝血综合征的发生率没有显着差异（分别为 4.3% 和 2.9%；P = 0.68）。结论：UESD 并没有加快整个患者群体的解剖速度。 CESD 和 UESD 在结直肠中可能是互补的，具体取决于 PLG。作者。这是 Thieme 根据知识共享署名-非衍生-非商业许可条款发表的开放获取文章，只要对原始作品给予适当的署名，就允许复制和复制。内容不得用于商业目的，也不得改编、重新混合、转换或构建。 （https://creativecommons.org/licenses/by-nc-nd/4.0/）。

This study compared procedure-related outcomes of conventional and underwater endoscopic submucosal dissection (ESD) for superficial colorectal neoplasms (SCNs).In this single-center, randomized controlled trial, patients with SCNs meeting the indications of the Japanese guidelines for ESD were randomly assigned to undergo conventional ESD (CESD) or underwater ESD (UESD) performed by an expert. The primary endpoint was dissection speed, defined as the specimen area per ESD time.We analyzed the data of 69 and 70 CESD and UESD cases, respectively; however, no significant differences were found in median dissection speed (17.4 and 19.9 mm2/min, respectively; P = 0.19). Multiple regression analysis revealed that the suitable positional relationship between the lesion and gravity direction (suitable PLG; non-gravity side for CESD and gravity side for UESD) was independently and positively associated with dissection speed (P < 0.001). En bloc resection was achieved without perforation in all cases. The incidence of post-ESD coagulation syndrome was not significantly different between the two groups (4.3% vs. 2.9%, respectively; P = 0.68). Conclusions: UESD did not expedite dissection speed in the overall patient population. CESD and UESD may be complementary in the colorectum depending on the PLG.The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).