Dissection of giant bulky colorectal lesions with muscle retracting sign (MRS+). Strategic management of gravitational traction during ESD might be the solution.

BACKGROUND

Large polyps have a higher risk of muscle retracting sign (MRS) positivity and display higher incomplete resection rates by endoscopic submucosal dissection (ESD). Techniques used are pocket creation methods and circumferential excision with traction application. This is a pilot study aiming to explore the efficacy and safety of a new ESD technique for MRS+ lesions.

METHODS

First, a 5-cm-long tunnel is created distally from the lesion, stabilizing the scope and enabling a deeper, flatter dissection plane. As the resection nears the lesion's center with suspected MRS, a local pocket is made for circular access to the muscle retraction tip. Effective gravity management is key for procedure success. Initially working against gravity (or opposite to the direction of gravity) allows better submucosal exposure. Subsequently, patient position is adjusted to allow the specimen to be pulled by gravity towards the dissection line. As a result, the altered position loosens the muscle layer, thereby reducing the tension at the MRS site and ultimately the perforation risk. Finally, a circumferential "360° dissection" is performed, with prophylactic coagulation applied at the muscle retraction tip to minimize bleeding from large feeding vessels.

RESULTS

Our cases series consists of 18 patients who underwent ESD for MRS+ colonic (3/18) and rectal (15/18) giant (> 4 cm) lesions, with en bloc and R0 resection documented in 16/18(89%) cases. Two patients were referred to surgery because of massive MRS+ and high risk of severe intraprocedural bleeding.

CONCLUSIONS

This case series demonstrates the efficacy of the aforementioned technique, yielding satisfactory results in the majority of cases-even those without curative resection. The application of this technique not only in giant rectal polyps but also in colonic protruding lesions amplifies the significance of the proposal.