The Pocket-Creation Procedure of Endoscopic Submucosal Dissection for Large Rectal Laterally Spreading Tumors.

This study introduces in detail a standardized Pocket Creation Method (PCM) of endoscopic submucosal dissection (ESD) protocol for the resection of large laterally spreading tumors (LST) of the rectum, aiming to overcome the limitations of traditional ESD by improving safety and dissection speed. The procedure is as follows: First, after marking the boundaries, a submucosal injection of indigo carmine-saline solution is administered to achieve sufficient lesion elevation. A disposable mucosal knife is then used to create an arc-shaped incision at the anorectal edge of the lesion, establishing the entry point for the submucosal tunnel. The tunnel is advanced orally along the plane between the submucosa and the muscularis propria, while maintaining the submucosal injection to ensure clear dissection layers. As the tunnel approaches the oral margin of the lesion, the scope is reversed to observe and complete the oral submucosal incision, determining the endpoint of dissection and achieving tunnel continuity from the anal to the oral side. Finally, the mucosal edges on the gravity and anti-gravity sides are cut sequentially to completely resect the lesion. During the surgery, vessels are pre-coagulated under direct visualization to avoid injury to the muscularis propria. Meanwhile, the retention of submucosal injection fluid enhances the "fluid cushion" effect, improving dissection speed and safety, and shortening the surgical time. By optimizing the tunnel vision and effectively maintaining the fluid cushion, this protocol overcomes the limitations of traditional ESD, enabling efficient, safe, and radical resection of large rectal LSTs, while avoiding the trauma associated with surgical resection. This technique offers an effective therapeutic strategy for the treatment of complex rectal lesions.