A catheter system for positioning of an instrument within a body. The catheter system includes a hub defining a lumen therethrough for passage of the instrument and an elongate tubular member defining a lumen therethrough. The lumen of the tubular member is in communication with the lumen of the hub. The system also includes a slitter member that is coupled to the hub. The slitter member is disposed to slit the tubular member. The slitter further includes a moveable member that is moveably coupled to the hub and that is coupled to the tubular member, the moveable member is operable to advance the elongate tubular member toward the slitter member as the moveable member is moved relative to the hub. The slitter member thereby slits the elongate tubular member.
