Catheter comprising an inner tubular member defining a fluid lumen and inflation lumen therein. An exterior surface of the inner tubular member defines a fluid flow port in fluid communication with the fluid lumen and located along a region of the inner tubular member. Catheter further includes an outer member having a distal section movable relative to the inner tubular member and having an interior surface. A piston balloon is coupled to the inner tubular member distal to the fluid flow port and is in fluid communication with the inflation lumen. A pressure chamber is in fluid communication with the fluid flow port. Fluid introduced through the inflation lumen inflates the piston balloon to seal against the interior surface and fluid introduced through the fluid flow port and into the pressure chamber applies a force to urge at least the distal section of the outer member in a proximal direction.
