A catheter flush, and fill unit having a connector (2) for connection to a catheter; a non-return valve (8) connected fluidically to the connector (2); a suction branch (3) connected to the non- return valve (8); and a filter (15) downstream from the suction branch (3). More specifically, a delivery branch (5) is located downstream from the suction branch (3), and a further non-return valve (9) connects the delivery branch (5) to the connector (2).