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

Summary

This study details a standardized PCM-ESD protocol for resecting large rectal LSTs, aiming to enhance dissection speed and prevent transmural perforation via submucosal tunneling.

Abstract

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.

Introduction

Colorectal cancer (CRC) remains a leading cause of cancer-related morbidity and mortality worldwide^1,2,3. Early detection and minimally invasive removal of precancerous lesions are pivotal for CRC prevention. Among these, laterally spreading tumors (LSTs) - characterized by their horizontal growth pattern along the mucosal surface rather than vertical protrusion - constitute a clinically significant subset. Histological studies confirm that LSTs exceeding 20-30 mm exhibit substantially higher rates of submucosal invasion compared to conventional polyps⁴

Protocol

The protocol was approved by the Institutional Review Board of the First Affiliated Hospital of Jinan University. The study included three patients who underwent PCM-ESD between August 2024 and July 2025. All procedures were performed in accordance with institutionally approved protocols after obtaining written informed consent from the patients. The materials and equipment used are listed in the Table of Materials.

1. Preoperative preparation

1. Obtain written informed consent from all patients after explaining the risks of perforation, bleeding, and possible conversion to surgery.
2. Perfo....

Results

This study successfully applied the Pocket Creation Method (PCM-ESD) in three consecutive patients with large rectal LSTs (4.2-7 cm), two of whom involved the anal line. All procedures were performed by dedicated therapeutic endoscopists, each with more than 3 years of independent ESD experience following formal training. Key demographic and clinical characteristics are detailed in Table 1. The cohort comprised one male and two females aged 57-87 years, including an 87-year-old male with an infrarenal ab.......

Discussion

The successful implementation of the Pocket-Creation Method for ESD (PCM-ESD) in resecting large rectal LSTs hinges on several critical steps within the protocol. First, the precise creation of the tunnel entry point via an arc-shaped incision at the anal side is paramount. This initial step must cleanly incise the mucosa and a portion of the submucosa to allow smooth scope insertion without damaging the underlying muscularis propria²³. Second, maintaining a durable fluid cushion and a cl.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Electrocoagulation	VIO 300D	erbe	An electrosurgical generator for tissue cutting and hemostasis
Endoscope	Olympus	GIF-H260J	A high-definition gastroscope for endoscopic procedure
Indigo carmine mucosal dye	MICRO-TECH	MTN-DYZ-15	Mucosal contrast enhancement submucosal injection
Single-use high-frequency knife	Olympus or MICRO-TECH	KD0655Q or MK-T-1-195	A disposable electrosurgical device enabling precise mucosal incision and submucosal dissection
Transparent cap	Olympus	D-201-11804	A distal attachment mounted on the endoscope tip