An apparatus for assisting the discharging of urine from a natural urinary bladder of a patient is disclosed. The apparatus comprises an implantable expandable member configured to be implanted inside of the urinary bladder, and an implantable control device for controlling the volume of the expandable member. The control device is configured to generate a pressure in the implantable expandable member exceeding 50 cm water pressure to assist the discharging of urine.
