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

This pocket creation method can be used to safely resect large rectal tumors endoscopically. The method works for large rectal laterally spreading tumors, even near the anal line. To begin, inject the indigo carmine saline solution immediately outside the planned resection margin to create a sustained fluid cushion.

Select the anal side marking point as the entry site. Make an arc-shaped incision at the anal rectal margin of the lesion using a disposable mucosal knife to create a mucosal flap and establish the tunnel entry point. Advance the endoscope into the submucosal space.

Then dissect the submucosal fibers horizontally using an ESD knife. Maintain a dissection plane immediately above the muscularis propria to avoid the more vascular superficial submucosa. Continue dissecting from the submucosal pocket toward the oral side until the tunnel extends beyond the oral tumor margin.

Inject additional indigo carmine saline solution as needed to maintain lift. Complete the submucosal incision on the oral side to clearly define the resection endpoint and achieve full communication between the anal side and oral side tunnels. Under direct vision, incise the mucosa along the pre-marked margin on the gravity-dependent side first, then proceed to the non-gravity side, advancing stepwise until the entire lesion is circumferentially freed.

Throughout the dissection, pre-coagulate any visible vessels with the ESD knife in soft coag mode. Engage the freed lesion with a snare or apply continuous endoscopic suction to extract the intact specimen en bloc. Inspect the post-resection bed and thermally coagulate it with hemostatic forceps.

The key demographic and clinical characteristics of three representative patients are summarized in this table. Preoperative evaluation revealed mild to moderate anemia in two patients. The mean dissection speed was 0.414 square centimeters per minute.

The procedures did not result in any intraoperative perforation. One patient experienced self-limiting hematochezia that was managed conservatively. The mean postoperative hospital stay was approximately five days.

Histopathological examination revealed high-grade intraepithelial neoplasia in all specimens. An important consideration to make while performing this protocol is to maintain a clear fluid cushion and avoid muscularis propria injury. Following this protocol, specimens can be used in histopathology for R0 margin assessment and cancer staging.

Future work may apply this protocol to duodenal lesions and integrate AI guidance.