Safety syringe with releasable anti-rotation retractable needle adapter

摘要

The syringe includes an adapter threaded into the distal end of the barrel and a plunger axially movable within the barrel. A stop and catch cooperate between the adapter and barrel end to prevent rotation of the adapter. Adapter and plunger engagement structures are carried by the plunger and adapter, respectively, to enable joint rotation of the plunger and adapter relative to the barrel to unthread the adapter from the barrel end and withdraw the adapter and needle carried thereby jointly with the plunger into the interior of the barrel. The engagement structures also include an element for engaging the catch in response to axial movement of the plunger to release the adapter for rotational movement relative to the barrel end and subsequent withdrawal of the adapter and needle carried thereby into the barrel.