A flush syringe assembly comprising: a barrel including a side wall having an inside surface defining a chamber for retaining fluid, an open proximal end, a distal end including a distal wall with a tip extending distally therefrom having a passageway therethrough in fluid communication with said chamber; a plunger rod disposed within the barrel, the plunger rod comprising a distal portion and a proximal portion, the plunger rod further comprising a distal end including a stopper slidably positioned in fluid-tight engagement with the inside surface of the barrel for drawing fluid into and driving fluid out of the chamber by movement of the stopper relative to the barrel, the plunger rod extending outwardly from the open proximal end of the barrel, the stopper having a distal surface; the flush syringe assembly characterized in that it further comprises: a reservoir collar integrally formed on the distal wall of the barrel and surrounding the tip, the reservoir collar including at least one side wall having an inside surface defining a compartment containing a disinfectant or antimicrobial agent, threads on the inside surface for connection to the hub of a vascular access device, a sealed distal end, a proximal end adjacent the distal wall of the barrel, with disinfection of the hub of the vascular access device by the disinfectant or antimicrobial agent; wherein the tip is located proximal of the distal edge of the reservoir collar such that a fully flat seal can be attached to the reservoir collar, thereby completely enclosing the tip and the disinfectant or antimicrobial agent, whereby the distal end of the reservoir collar is sealed by a removable seal, completely enclosing the tip and the disinfectant, the removable seal comprises an aluminum or multi-layer polymer film peel back top, and an aluminum lining adhered to the inside surface of the at least one side wall of the reservoir collar. a barrel including a side wall having an inside surface defining a chamber for retaining fluid, an open proximal end, a distal end including a distal wall with a tip extending distally therefrom having a passageway therethrough in fluid communication with said chamber; a plunger rod disposed within the barrel, the plunger rod comprising a distal portion and a proximal portion, the plunger rod further comprising a distal end including a stopper slidably positioned in fluid-tight engagement with the inside surface of the barrel for drawing fluid into and driving fluid out of the chamber by movement of the stopper relative to the barrel, the plunger rod extending outwardly from the open proximal end of the barrel, the stopper having a distal surface; the flush syringe assembly characterized in that it further comprises: a reservoir collar integrally formed on the distal wall of the barrel and surrounding the tip, the reservoir collar including at least one side wall having an inside surface defining a compartment containing a disinfectant or antimicrobial agent, threads on the inside surface for connection to the hub of a vascular access device, a sealed distal end, a proximal end adjacent the distal wall of the barrel, with disinfection of the hub of the vascular access device by the disinfectant or antimicrobial agent; wherein the tip is located proximal of the distal edge of the reservoir collar such that a fully flat seal can be attached to the reservoir collar, thereby completely enclosing the tip and the disinfectant or antimicrobial agent, whereby the distal end of the reservoir collar is sealed by a removable seal, completely enclosing the tip and the disinfectant, the removable seal comprises an aluminum or multi-layer polymer film peel back top, and an aluminum lining adhered to the inside surface of the at least one side wall of the reservoir collar.