Positive displacement fluid lock ports for use in combination with an indwelling catheter and a syringe during a flushing/locking procedure are provided. The fluid lock port includes a housing having a distal and a proximal end; a resilient conduit supported within the housing, wherein the conduit defines a lumen therethrough; and at least one biasing member supported in the housing and being operatively associatable with the resilient conduit. The at least one biasing member has a first condition restrained from deforming the resilient conduit and a second condition operatively engaged with the resilient conduit to at least partially occlude the lumen of the resilient conduit.