Abstract: A system for aseptically removing urine from a primary drainage bag attached to a patient by conventional catheter means which includes a separate sterile disposable transfer bag. Rigid laterally extending spout interconnects the two bags when drainage is desired. The primary drainage bag is formed in the preferred embodiment with an outlet provided with self-closing flaps and slip valves which may be penetrated by the spout mounted on the transfer bag. Locking rib and groove means secure the spout in the outlet and a removable cap covers the outlet when the transfer bag is not attached. In a second form, the spout and valve means are on the primary drainage bag and transfer bag respectively.