A system and method for draining at least one type of bodily fluid from a patient, including a chamber capable of being adjusted to hold one of at least a first volume of fluid and a second, smaller volume of fluid. The chamber has an inlet end with a barrier defining an opening and has an outlet end defining an outlet passage. The system further includes a valve with a valve seat and a valve closure member to define a usable volume within the chamber, and a movable adjustment member with a shaft passable through the opening in the barrier and terminating within the chamber at a first end. The first end of the shaft is connected to the valve seat, and the shaft has a plurality of features along its length engagable with corresponding engagement features in a fixed relationship with the barrier to enable the shaft to be advanced into the chamber to reduce the usable volume to be less than the first volume.
