Medical circuits for use in fluid infusion, blood infusion, parenteral nutrition administration, etc. are occasionally connected and disconnected for continuously or temporarily supplying fluids such as a plurality of medicinal solutions, blood, liquid diet, etc. It is well known in the art that connectors are incorporated into those medical circuits for connection and disconnection (see, for example, Japanese Laid-Open Patent Publication No. 9-108361 and Japanese Patent Publication No. 5-32071).
A typical one of the connectors is a three-way cock. The three-way cock comprises a single male lure connector and two female lure connectors which are fitted to each other to connect the circuit. However, the three-way cock is disadvantageous in that it is vulnerable to bacterial contamination because a fluid passage region thereof is exposed to external air when the circuit is disconnected. Particularly, the female joint is frequently brought into contact with external air because it is used many times for repeated connection and disconnection.
There is known a connector having a valve body in a female joint port for preventing a fluid passage region thereof from being exposed to external air. According to the connector, the valve body is pierced by a needle or a male connector is inserted into the valve body that has a slit, opening the fluid passage. After the needle or the male connector is removed, the valve body is closed again, preventing the fluid passage from being exposed to external air.
However, the above connectors are problematic in that since the valve body is mounted in only one female joint port, when the male connector is removed from the other female joint port, the female joint port is exposed to the atmospheric air.
The above connectors are also disadvantageous in that the female joint ports tend to trap a fluid, making it difficult for a medical solution to flow in its entirety so that an environment for easy bacterial growth tends to be created. Furthermore, though the connector needs to be filled with a fluid such as a medical solution or the like before it is used, existing air in the connector cannot easily be removed.
Further, when a needle or a male connector is attached to and removed from a female joint port, the contents of the connector are liable to change. For example, if the contents of the connector increase when the male connector is removed, the blood flows from a blood vessel catheter connected to the connector back into the blood vessel catheter, causing the blood vessel catheter to be closed off.