A blood sequestration device configured to isolate an initial, potentially contaminated portion of blood from a flow of blood from vasculature of a patient during collection of a blood sample, the blood sequestration device including: a needle assembly (402, 414), a sequestration body, a needle housing, and a biasing mechanism; the needle assembly including: a needle having a sharpened distal tip, and a needle hub, a proximal end of the needle being operably coupled to the needle hub; the sequestration body being configured to coaxially ride over at least a portion of the needle, the sequestration body including: a vented sequestration chamber, an outlet port, and a catheter portion, the catheter portion including a catheter hub and a catheter tube; the sequestration chamber being configured to isolate an initial portion of blood from a flow of blood; a proximal end of the sequestration chamber defining a vent path configured to enable the escape of gas initially trapped within the sequestration chamber, the vent path being sealed at one end by a septum; the septum being configured to enable at least a portion of the needle to pass through the septum during insertion of the catheter tube into a vein of the patient; the needle hub being slidably coupled to the needle housing for movement between an initial, blood collection position, in which at least a portion of the needle extends beyond the needle housing, and a safe position, in which the sharpened distal tip of the needle is housed within the needle housing; the biasing mechanism being operably coupled between the needle hub and a distal end of the needle housing and configured to bias the needle to the safe position. a needle assembly (402, 414), a sequestration body, a needle housing, and a biasing mechanism; the needle assembly including: a needle having a sharpened distal tip, and a needle hub, a proximal end of the needle being operably coupled to the needle hub; a needle having a sharpened distal tip, and a needle hub, a proximal end of the needle being operably coupled to the needle hub; the sequestration body being configured to coaxially ride over at least a portion of the needle, the sequestration body including: a vented sequestration chamber, an outlet port, and a catheter portion, the catheter portion including a catheter hub and a catheter tube; a vented sequestration chamber, an outlet port, and a catheter portion, the catheter portion including a catheter hub and a catheter tube; the sequestration chamber being configured to isolate an initial portion of blood from a flow of blood; a proximal end of the sequestration chamber defining a vent path configured to enable the escape of gas initially trapped within the sequestration chamber, the vent path being sealed at one end by a septum; the septum being configured to enable at least a portion of the needle to pass through the septum during insertion of the catheter tube into a vein of the patient; the needle hub being slidably coupled to the needle housing for movement between an initial, blood collection position, in which at least a portion of the needle extends beyond the needle housing, and a safe position, in which the sharpened distal tip of the needle is housed within the needle housing; the biasing mechanism being operably coupled between the needle hub and a distal end of the needle housing and configured to bias the needle to the safe position.