A syringe assembly comprising: a barrel including a cylindrical sidewall having an interior surface defining a chamber for retaining fluid, an open proximal end and a distal end including a distal wall having an opening therethrough in fluid communication with said chamber , the chamber further having a first inner diameter, a locking rib adjacent to the open proximal end having a second inner diameter, wherein the second inner diameter is less than the first inner diameter, an increased diameter region located proximally from the locking rib having a third inner diameter greater than the first and second inner diameters, and a diameter transition region extending between the locking rib and the increased diameter region; an elongate plunger rod having a proximal end , a distal end , a stopper-engaging portion located at the distal end of the plunger rod , a thumb press at the proximal end of the plunger rod , a main body portion extending between the distal and proximal ends of the plunger rod , an annular protrusion extending radially from the plunger rod having an outer diameter greater than the second inner diameter and the plunger rod further including at least one frangible portion ; a stopper having a proximal end and a distal end , the stopper attached to the stopper-engaging portion of the plunger rod , the stopper being distally and proximally movable a pre-selected axial distance relative to the stopper-engaging portion , such that when the distal end of the stopper is in contact with the distal wall of the barrel , the annular protrusion is permitted to advance distally past the locking rib in the barrel and lock the plunger rod in the barrel to prevent reuse of the syringe assembly, characterized by a use detection system including a visual display disposed on the stopper-engaging portion of the plunger rod , the visual display being fully visible before an initial distally directed force is applied to the plunger rod . a barrel including a cylindrical sidewall having an interior surface defining a chamber for retaining fluid, an open proximal end and a distal end including a distal wall having an opening therethrough in fluid communication with said chamber , the chamber further having a first inner diameter, a locking rib adjacent to the open proximal end having a second inner diameter, wherein the second inner diameter is less than the first inner diameter, an increased diameter region located proximally from the locking rib having a third inner diameter greater than the first and second inner diameters, and a diameter transition region extending between the locking rib and the increased diameter region; an elongate plunger rod having a proximal end , a distal end , a stopper-engaging portion located at the distal end of the plunger rod , a thumb press at the proximal end of the plunger rod , a main body portion extending between the distal and proximal ends of the plunger rod , an annular protrusion extending radially from the plunger rod having an outer diameter greater than the second inner diameter and the plunger rod further including at least one frangible portion ; a stopper having a proximal end and a distal end , the stopper attached to the stopper-engaging portion of the plunger rod , the stopper being distally and proximally movable a pre-selected axial distance relative to the stopper-engaging portion , such that when the distal end of the stopper is in contact with the distal wall of the barrel , the annular protrusion is permitted to advance distally past the locking rib in the barrel and lock the plunger rod in the barrel to prevent reuse of the syringe assembly, <EOS>