Patent ID: 7972303

Claim:
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; an elongate plunger rod including a proximal end, a distal end, and a main body extending between the proximal and distal end, the plunger rod being distally and proximally movable within said chamber, the proximal end including a thumb press having proximal end, a distal end, and a diameter, the distal end of the plunger rod including a stopper-engaging portion; an annular extension protruding proximally from the proximal end of the barrel having a diameter greater than the diameter of the thumb press; and a stopper having a proximal end and a distal end, the stopper attached to the stopper-engaging portion of the plunger rod and distally and proximally movable relative to the stopper-engaging portion for a pre-selected axial distance, such that when the distal end of the stopper is in contact with the distal wall of the barrel, the thumb press is permitted to advance distally into the annular extension and the annular extension at least partially envelopes a portion of the thumb press to prevent the user from accessing the thumb press and moving the plunger rod in a proximal direction, the stopper-engaging portion comprising a visual indicator being fully visible when the stopper-engaging portion is proximally moved relative to the stopper.