Endoscopic submucosal dissection using a hook knife

The hook knife is a robust device for marking and cutting mucosa, submucosal fibers, and vessels, as well as for hemostasis of minor bleeding. The tip of the knife is bent at a right angle. The length of the hook part is 1.3 mm and that of the arm is 4.5 mm. The knife is hosted within an outer sheath. The tip of the sheath has a hood-like shape that allows the hook of the knife to be retracted within it. The direction of the hook can be adjusted by rotating a handle located on the proximal side of the knife. The hook direction is easily adjusted when the handle is simultaneously rotated and moved slightly back and forth. The hook direction is fixed when the handle is maximally extended. Importantly, the direction of the hook knife should be controlled and kept parallel with the muscularis propria layer to prevent perforation during endoscopic submucosal dissection. When minor bleeding occurs during mucosal incision or dissection, it can be stopped using the hook knife by positioning the tip of the knife close to the bleeding site and using the spray mode to obtain hemostasis.