A flush syringe assembly (100, 200) comprising: a barrel (110, 210) (110, 210) including a side wall (111, 211) having an inside surface (112, 163, 212) defining a chamber (114, 214) for retaining fluid, and outside surface (113, 213), an open proximal end (115, 215), a distal end (116, 216) including a distal wall (117, 217) having an aperture (118, 218) therethrough in fluid communication with the chamber (114, 214); an elongate plunger rod disposed within the barrel (110, 210), the plunger rod comprising a distal end including a stopper slidably positioned in fluid-tight contact with the inside surface (112, 163, 212) of the barrel (110, 210) so that distal movement of the stopper relative to the barrel (110, 210) pushes fluid out of the barrel (110, 210); and a cap comprising a passageway therethrough in fluid communication with the chamber (114, 214), the cap including a Luer connector on a distal end and being releasably connectable to a vascular access device and a proximal end releasably attachable to the barrel (110, 210); characterized by the flush syringe assembly (100, 200) further comprising a plug positioned adjacent to the distal end (116, 216) of the barrel (110, 210) and in contact with the proximal end of the cap, the plug having a proximal face (141, 241) and a sidewall (144, 244) extending distally therefrom, the sidewall (144, 244) including a plurality of openings (143, 243) that allow fluid communication between the chamber (114, 214) and the VAD, the entire plug being movable by distally directed force applied by the stopper from a proximal open position that permits fluid flow between the chamber (114, 214) and the VAD through the plurality of openings (143, 243) and a distal closed position that prevents fluid communication between a blood vessel and the chamber (114, 214), wherein when the valve has been moved into the distal closed position, the cap and valve can be released from the distal end of the barrel and left attached to the VAD. a barrel (110, 210) (110, 210) including a side wall (111, 211) having an inside surface (112, 163, 212) defining a chamber (114, 214) for retaining fluid, and outside surface (113, 213), an open proximal end (115, 215), a distal end (116, 216) including a distal wall (117, 217) having an aperture (118, 218) therethrough in fluid communication with the chamber (114, 214); an elongate plunger rod disposed within the barrel (110, 210), the plunger rod comprising a distal end including a stopper slidably positioned in fluid-tight contact with the inside surface (112, 163, 212) of the barrel (110, 210) so that distal movement of the stopper relative to the barrel (110, 210) pushes fluid out of the barrel (110, 210); and a cap comprising a passageway therethrough in fluid communication with the chamber (114, 214), the cap including a Luer connector on a distal end and being releasably connectable to a vascular access device and a proximal end releasably attachable to the barrel (110, 210); characterized by the flush syringe assembly (100, 200) further comprising a plug positioned adjacent to the distal end (116, 216) of the barrel (110, 210) and in contact with the proximal end of the cap, the plug having a proximal face (141, 241) and a sidewall (144, 244) extending distally therefrom, the sidewall (144, 244) including a plurality of openings (143, 243) that allow fluid communication between the chamber (114, 214) and the VAD, the entire plug being movable by distally directed force applied by the stopper from a proximal open position that permits fluid flow between the chamber (114, 214) and the VAD through the plurality of openings (143, 243) and a distal closed position that prevents fluid communication between a blood vessel and the chamber (114, 214), wherein when the valve has been moved into the distal closed position, the cap and valve can be released from the distal end of the barrel and left attached to the VAD.