A blood collection needle assembly includes a holder body having a tube receiving
chamber and a needle receiving chamber. A proximal needle is mounted to the holder
body and projects into the tube receiving chamber. A distal needle is slidably
mounted in alignment with the needle receiving chamber. A spring is provided to
urge distal needle into the needle receiving chamber, and a trigger is provided
for selectively permitting or preventing proximal movement of the distal needle.
A transverse passage between the two needles is formed from a transparent material
and provides indication of venus axis. The blood collection needle assembly is
used to collect a sample of blood in a conventional manner. After collection of
the blood, the trigger is actuated to release the distal needle and the spring
propels the distal needle in a proximal direction for safe shielding within the
needle receiving chamber of the holder body.