COLORECTAL ESD USING A COMBINATION OF THE POCKET-CREATION METHOD AND THE UNDERWATER TECHNIQUE

Abstract

ESD of colorectal tumors has been established as a minimally invasive technique that can reliably achieve en bloc resection. However, colorectal ESD has several unique technical difficulties. Endoscopists have attempted to overcome these difficulties in colorectal ESD. The pocket-creation method (PCM) is one such procedure and has four advantages: 1) prevention of leakage of locally injected solution, 2) both strong traction and countertraction by the tip of the hood, 3) easy tangential approach to the submucosal layer by enabling optimal angle adjustment even when the muscle layer is oriented vertically, and 4) stabilization of the tip of the endoscope. The first report stated that PCM enabled ESD in cases of giant subpedunculated colorectal tumors with severe fibrosis. Recently, PCM has been shown to have advantages not only for colorectal tumors, but also for gastric and duodenal tumors. A technical review by the European Society for Gastrointestinal Endoscopy (ESGE) reported that the advantages of PCM are easier to understand when it is recognized as a type of traction method. Meanwhile, the underwater technique, in which the lumen is filled with saline, is useful for treating gastrointestinal neoplasms. Underwater endoscopic mucosal resection without injection has already been established as a standard treatment for duodenal and colorectal tumors. The advantages of underwater treatment include mucosal contraction, natural traction owing to buoyancy, and improved visibility. PCM and underwater treatment appear to be complementary in maintaining visibility in a narrow space. In general, traction gradually disappears during pocket opening; however, natural traction, such as buoyancy, can be maintained continuously underwater, leading to a synergistic effect. This article outlines the background and actual techniques of PCM and discusses their integration with those of the underwater technique, as well as the application of new equipment with reference to the latest information.