Patent ID: 7507200

Claim:
A medical instrument system using a diathermic snare and an endoscope in combination with each other, the endoscope including a substantially cylindrical cap section mounted on a distal end of an elongated inserting section which is to be inserted into a body cavity, wherein the cap section has a flange-shaped projection that projects inward from the inner circumference surface of the distal end; wherein the diathermic snare comprises: a flexible sheath; an operation wire inserted into the flexible sheath to be movable forwards and backwards: and a snare wire coupled to the distal end of the operation wire; and wherein, when the endoscope and the diathermic snare is used in combination with each other, a loop section which expands to one of a substantially circular or elliptical loop when the snare wire is projected from the sheath is formed, the loop section expanding along the inner circumference of the cap section, the medical instrument system comprising a distal-end projection which projects in the direction that intersects a plane of the loop at the distal end of the loop section and is fitted on an inner wall of the cap section when the loop section expands along the inner circumference of the cap section.