The present invention is an improved catheter, in particular, a Foley catheter. The preferred embodiment of the invention is a catheter with three lumens. The largest lumen is the drainage lumen. The side balloon lumen has a removable one-way female Luer valve threaded onto the distal end of the side balloon lumen. The removable Luer valve allows a user to drain the balloon by passive equilibrium to atmospheric pressure by removing the valve from the lumen. Alternately, the lumen can be drained by syringe. The temperature sensor lumen contains a sensor lead with a Teflon(R) outside jacket that allows the lead to more easily slide within the lumen when the lumen is stretched or retracts. The sensor lead is also preferably fixed only to the distal end of the lumen so the lead will not stretch with the lumen, but would move freely within the lumen.
