US Patent 7905856 Introducer sheath with retainer

A surgical introducer sheath comprising a first member having a first longitudinally extending lumen dimensioned to receive a surgical instrument therethrough, a second member having a second longitudinally extending lumen dimensioned to receive the first member, and a retainer adjacent a distal portion of the second member movable from a first retracted position to a second extended position to limit proximal movement of the introducer sheath. Rotational movement of the second member in a first direction moves the retainer to the extended position and rotational movement of the second member in a second direction moves the retainer to a retracted position.