Abstract

A hypodermic injection system (7) with a retractable needle (9) wherein the needle (9) retracts within an interior cavity of a syringe plunger (59), such that the needle (9) is confinedly held within the plunger (59). A cylindrical spring housing assembly (21) has resilient fingers (23) which captures a spring (15) biasly holding a needle holder (11) against the retaining force of resilient fingers (23). The plunger (59) has a frangible end (65), which dissociates when the outwardly tapered shoulders (68) spread the resilient fingers (23), allowing the coiled spring (15) to eject the needle (9) and its holder (11) into the interior cavity (71) of the plunger (59). A body fluid sampling embodiment employs the same functional elements except the plunger (59") is shorter and contains a linking (137) that communicates with a vacuum container (147). The container allows fluid sampling and provides the structure to release the spring (15 ") retracting the needle (9"). The retractable needle embodiment is also employed with an insertion needle (9'") that guides a catheter tube (154) below the skin of a patient and into the vein, and allows retraction of the insertion needle (9'") thereby avoiding accidental pricking of the health care worker by the insertion needle (9'").