Apparatus configured to be secured to intravenous tubing to establish a needleless injection/aspiration port on the IV tubing, the apparatus comprising: an IV tubing-engaging portion having an internal surface configured to snugly engage an external surface of the IV tubing; a tubular branch portion extending from the IV tubing-engaging portion, the branch portion including a lumen; characterized in that it further comprises: a first elastomeric sealing member located at a junction of the IV tubing-engaging portion and the branch portion, the sealing member fluidly isolating the lumen of the branch portion from an interior of the IV tubing-engaging portion; a piston portion engaging the branch portion, a central shaft of the piston portion disposed at least partially within the lumen of the branch portion, the central shaft including a lumen; a puncturing member extending distally from the central shaft and including a lumen and a pointed distal tip; and a valve member engaging a proximal end of the piston portion, the valve member including a second elastomeric sealing member that provides selective sealing of a proximal end of the piston portion; wherein relative translation of the piston portion with respect to the branch portion in a first direction drives the pointed tip of the puncturing member through the first elastomeric sealing member and through a sidewall of the IV tubing to establish fluid communication between an interior of the IV tubing and the lumen in the puncturing member. an IV tubing-engaging portion having an internal surface configured to snugly engage an external surface of the IV tubing; a tubular branch portion extending from the IV tubing-engaging portion, the branch portion including a lumen; characterized in that it further comprises: a first elastomeric sealing member located at a junction of the IV tubing-engaging portion and the branch portion, the sealing member fluidly isolating the lumen of the branch portion from an interior of the IV tubing-engaging portion; a piston portion engaging the branch portion, a central shaft of the piston portion disposed at least partially within the lumen of the branch portion, the central shaft including a lumen; a puncturing member extending distally from the central shaft and including a lumen and a pointed distal tip; and a valve member engaging a proximal end of the piston portion, the valve member including a second elastomeric sealing member that provides selective sealing of a proximal end of the piston portion; a first elastomeric sealing member located at a junction of the IV tubing-engaging portion and the branch portion, the sealing member fluidly isolating the lumen of the branch portion from an interior of the IV tubing-engaging portion; a piston portion engaging the branch portion, a central shaft of the piston portion disposed at least partially within the lumen of the branch portion, the central shaft including a lumen; a puncturing member extending distally from the central shaft and including a lumen and a pointed distal tip; and a valve member engaging a proximal end of the piston portion, the valve member including a second elastomeric sealing member that provides selective sealing of a proximal end of the piston portion; wherein relative translation of the piston portion with respect to the branch portion in a first direction drives the pointed tip of the puncturing member through the first elastomeric sealing member and through a sidewall of the IV tubing to establish fluid communication between an interior of the IV tubing and the lumen in the puncturing member.