Medical valve with positive flow characteristics

A medical valve for selectively permitting fluid to flow between a first medical device and a second medical device, the valve comprising:

• a housing having an interface suitable for receiving a connector portion of the first medical device;
• and
• a seal made of a flexible material, the seal having a downstream end in fluid communication with the interface, an upstream end suitable for receiving the second medical device, and a normally substantially closed passage in fluid communication with the downstream end and the upstream end,
• the seal including a body made of flexible material and having a downstream end and an upstream end opposite the downstream end;
• a lead lumen formed in the downstream end of the body and in fluid communication with the passage;
• a neck formed at the upstream end of the body;
• and
• a transverse flange at an end of the neck opposite the body, the transverse flange having at least one opening in fluid communication with the passage;
• and
• the passage having a relatively small interior volume when in an undisturbed state and a larger interior volume upon the introduction of the second medical device into the upstream end of the passage, the passage retracting to define a restricted flow path and a relatively small interior volume upon the withdrawal of the second medical device from the seal, the upstream end initially being sealed as the second medical device is withdrawn, so that a fluid occupying the interior volume is forced toward the downstream end as the passage walls collapse.