A catheter includes a proximal end, a distal end, a tubular member, and an inner member extending through the tubular member. The inner member is movable axially relative to the tubular member. The catheter also includes a seal member including a first portion and a second portion. The seal member extends between the tubular member and the inner member. The first portion of the seal member remains stationary relative to the tubular member, and the second portion of the seal member remains stationary relative to the inner member during relative axial movement between the tubular member and the inner member.