Patent ID: 8585653

Claim:
A method of preventing leakage of blood from a needle assembly comprising: a) receiving blood through a patient puncture tip and into a first chamber of the needle assembly, the needle assembly comprising: i) a needle housing defining a housing interior, said housing comprising the patient puncture tip extending from a first end of the housing and a non-patient puncture tip extending from a second end of the housing, and ii) a porous vent positioned within the housing interior and separating the housing interior into a first chamber and a second chamber, with the non-patient puncture tip and the patient puncture tip being in fluid communication with each other within the first chamber such that the sole communication path between the housing interior and the external environment is via the patient puncture tip, the porous vent including pores for passage of blood therethrough from the first chamber into the second chamber; b) establishing fluid communication between the non-patient puncture tip and a negative pressure source such that blood contained within the first chamber is drawn out of the non-patient puncture tip and air is drawn out of the second chamber through the porous vent, thereby establishing a negative pressure within the second chamber relative to the external environment of the needle assembly such that blood flows through a cannula into the first chamber and contacts the porous vent; and c) drawing blood through the pores of the porous vent toward the second chamber based upon the negative pressure established within the second chamber such that blood contained within a lumen of the patient puncture tip is displaced away from the patient puncture tip and toward the second chamber.