Positive flow valve

A closed system, spikeless, positive-flow valve device includes a body defining an internal cavity. At the proximal end of the body is an opening which is preferably sufficiently large to receive an ANSI standard tip of a medical implement. The valve includes a plastic, resilient silicon seal which fills the upper cavity and opening with an oval seal cap having a slit. The opening presses the oval seal cap to keep the slit closed in the decompressed state. The slit opens as the nose of the medical implement compresses the seal into the cavity and the seal cap is free from the opening. The housing also includes a fluid space which facilitates fluid flow between the medical implement and a catheter tip. The fluid space within the valve automatically and reversibly increases upon insertion of the medical implement into the cavity and decreases upon withdrawal of the medical implement, such that a positive flow from the valve toward the catheter tip is effected upon withdrawal of the medical implement, thereby preventing a flow of blood from a patient into the catheter when the medical implement is removed from the valve.