A medical instrument for use in EMR and ESD procedures includes a proximal handle having an electrical connection plug, a slidable handle portion, and a rotatable handle portion. The medical instrument includes a sheath extending from the proximal handle, the sheath comprising a lumen and a distal end away from the proximal handle. A cutting assembly extends through the sheath and comprises a wire and a working end. The cutting assembly and sheath are moveable relative to each other to cover and reveal the working end such that the working end has a retracted position and a working position. The working end comprises a flexible knife comprising a distal end, a proximal end, and an insulated portion. An insulated spear-shaped tip is provided at the distal end of the flexible knife, the insulated spear-shaped tip preventing cutting of a layer other than a mucosal layer or a submucosal layer.
