Endoscopic submucosal dissection (ESD) for gastric subepithelial lesions, particularly those originating from the muscularis propria, is technically challenging due to limited submucosal exposure, poor maneuverability of conventional knives, and high instrument costs. These factors can prolong procedure time and increase the risk of perforation or bleeding.

We developed a cost-effective modified-snare knife (MSK) from a standard snare, reducing instrument cost to one-ninth of a conventional dual knife. Combined with clip-and-dental floss pre-traction, this innovation provides sustained traction and improves submucosal visualization, enhancing dissection precision and safety.

The technique was successfully applied to resect a 2.2 cm gastric fundus GIST originating from the muscularis propria. En bloc resection was achieved in 50 minutes without moderate or severe adverse events. Histopathology confirmed complete removal of a spindle cell GIST.

The combined use of MSK and clip-and-dental floss traction offers a safe, feasible, and highly cost-effective alternative to conventional ESD for gastric subepithelial tumors. This approach improves exposure and dissection efficiency while significantly reducing operational costs.