Disclosed is an assembly of parts for an endourological procedure including a tubular sheath and an introducer, the tubular sheath being removably mounted on the introducer. The tubular sheath includes a first and a second lumen of which the second lumen is openable to shift a guidewire from a position inside the second lumen to a position outside and next to the tubular sheath. Disclosed are also access sheaths and a method of performing an endourological procedure.
