Abstract: A hypodermic syringe assembly is provided with a syringe barrel and a safety shield telescoped over the syringe barrel and movable from a proximal position to a distal position. The safety shield is irreversibly lockable in the distal position on the syringe barrel to protectively shield a used needle cannula. The safety shield is releasably retained in a proximal position by engagement of a protrusion on the barrel and a groove on the shield. Engagement between the protrusion and the stop block can be overcome by rotating the safety shield. The safety shield may then be moved into an irreversible shielding position surrounding the needle cannula. The releasable retention of the safety shield in its proximal position prevents inadvertent distal movement of the safety shield.

Abstract: A safety syringe assembly includes a hypodermic syringe having a syringe barrel with opposed proximal and distal ends. A needle cannula is mounted to the distal end of the barrel. A collar mounted around the syringe barrel includes at least one radially inwardly directed recess. A safety shield is positioned over the syringe barrel for telescoping movement from a proximal position where the needle cannula is exposed to a distal position where the syringe safety shield protectively surrounds the needle cannula. The safety shield is rotatable with respect to the barrel when the safety shield is in its proximal position. The safety shield includes an inside surface having at least one inwardly directed projection sized and positioned to pass through the recess in the collar when the safety shield is rotated with respect to the barrel to align the projection and the recess. When alignment is achieved the safety shield can be moved form the proximal position to the distal position.