A ureteral access sheath adapted for insertion into a urethra includes an elongate tube extending between a proximal end and a distal end. A handle assembly is disposed at the proximal end and includes enlarged portions which inhibit migration of the sheath into the urethra. The enlarged portions are shaped like the bell of a horn with a concave, distally-facing outer surface and a convex, proximally-facing inner surface. The inner surface functions as a funnel while the outer surface is sized and configured to receive adjacent fingers of a user's hand held in its natural position. In an associated method, this shape of the handle assembly facilitates maintaining the sheath in a stationary position during insertion and removal of instrumentation. The handle assembly can be movable on the tube to facilitate variation of the sheath link in situ.