Hypodermic needle guard and method to prevent needle stick injuries

Claim 1

A medical instrument comprising: a barrel for holding fluid; a needle hub having a needle attached thereon, said needle hub being attachable and detachable from said barrel; a needle guard for protecting a user of said medical instrument from needle sticks, said needle guard including: a fitting having an exterior portion and being adapted to be disposed on said needle hub that is attachable on and detachable from said barrel; a hollow protective sleeve having an interior surface and a guide means for slidably connecting said interior surface of said sleeve with said exterior portion of said fitting, said sleeve thereby being movable on said fitting axially in the direction of the length of said needle between a non-protective retracted position exposing said needle and a protective extended position covering said needle whereby said sleeve in said protective extended position protrudes beyond the tip of said needle such that said sleeve defines a guard which prevents further access to said needle; means for irreversibly locking said sleeve only in said protective extended position relative to said fitting, whereby axial movement of said sleeve relative to said fitting is prevented once said sleeve has been moved to said protective extended position; and said exterior portion of said fitting includes at least one tang extending radially outwardly from the fitting and axially in the direction of the needle for engaging said interior surface of said sleeve and for retaining the sleeve in the protective extended position covering the needle; wherein said needle guard, said needle, and said needle hub are removable as one unit from said barrel of said medical instrument by detachment of said needle hub from said barrel when said sleeve is in said protective extended position.