Patent ID: 7896876

Claim:
A high-frequency incision instrument for an endoscope including an electrically insulative flexible sheath constituted of a distal tube disposed at a tip portion thereof and a proximal tube disposed on a proximal side such that one is loosely inserted into the other so as to rotate around an axial line thereof, a high-frequency electrode exposed along a lateral surface of the distal tube and connected to a conductive operating wire extending throughout inside the distal tube and the proximal tube, so that a high-frequency current is supplied to the high-frequency electrode through the operating wire, and so that rotating the operating wire at a proximal end portion of the proximal tube around an axial line causes the distal tube to rotate around the axial line with respect to the proximal tube thus to change an orientation of the high-frequency electrode, comprising: a water inlet located at a proximal end portion of the proximal tube for supplying water into the proximal tube; a water injection outlet located on the lateral surface of the distal tube for injecting the water supplied into the proximal tube out of the distal tube; and a seal ring that prevents the water from leaking through a joint portion between the distal tube and the proximal tube, attached to an outer surface of one of the distal tube and the proximal tube that is smaller in outer diameter, wherein pulling the operating wire toward a proximal side by manipulation by hand causes the seal ring to intrude into the joint portion between the distal tube and the proximal tube, to thereby prevent the water leakage, and pushing forward the operating wire by manipulation by hand releases the seal ring from the joint portion between the distal tube and the proximal tube, thereby allowing the distal tube to rotate following a rotating motion of the operating wire around the axial line, thus to change an orientation of the high-frequency electrode.