Abstract

A hypodermic needle has a retractable tubular sheath slidably mounted on its forward end and movable relative thereto between a rearward retracted position exposing the front end of the needle and a forward protective position enclosing the front end of the needle. In one embodiment, a spring within the sheath urges the sheath to the forward protective position enclosing the front end of the needle. The rear of the sheath cooperates with pins on the needle to engage them upon relative rotation in one direction to allow rotation as a single unit to connect the needle to fluid ejection or withdrawal members. Relative rotation in the opposite direction disengages the pins allowing the sheath to be moved rearward causing the front end of the needle to protrude beyond the front end of the sheath and to lock the needle and sheath together upon further relative rotation in the opposite direction to disconnect and dispose of the needle without inadvertent injury by contact with the needle. Another embodiment has protrusions on the needle and a retractable sheath slidably mounted on the needle and movable between a rearward retracted position exposing the needle front end and a forward protective position engaging the protrusions and covering the front end of the needle. A further modification has a tubular catheter slidably received on the needle for hypodermic penetration therewith which is removably connected to the sheath whereby when the sheath and needle are removed from the catheter only the catheter remains in place.