Retractable fluid collection device

A permanently automatically retractable fluid collecting device has an elongated outer protective tube member having a front end with a port and a coaxial telescoping plunger having a forward end for frictionally engaging a needle holder for a canula needle. The plunger is slidingly mounted in the elongated tube member for selective movement in an axial direction toward and away from the front. The front end of the plunger has an opening having inwardly facing surfaces for frictionally engaging outwardly facing surfaces of the periphery of a needle holder along a slidable axially oriented interface. When the plunger is moved forward to extend the needle from the port, a catch holds it in a first position. Biasing force is applied to the needle holder being frictionally held in the front of the plunger. A sample tube is installable in the opening at the rear of the plunger. After taking a sample and removing the collection tube, a plunger cap is repositioned to allow the plunger to be moved from the first position toward a second position causing sliding separation of the plunger from the needle holder along the slidable interface. The biasing force overcomes remaining frictional holding force at the sliding interface to cause immediate and permanent retraction of the needle holder into a cavity comprising a retraction space within the plunger.