Systems and methods for assessing fluids from a patient are disclosed. The system includes a receptacle including an inlet port, an outlet port, and a third port； a valve system in fluidic communication with the receptacle； and one or more features in the receptacle to aid in optical imaging of fluids. The system has a fill mode and a flush mode. In the fill mode, the valve system directs suction from a vacuum source through the third port into the receptacle, thereby drawing fluid through the inlet port into the receptacle. In the flush mode, the valve system directs suction from the vacuum source through the outlet port, thereby drawing fluid through the outlet port out of the receptacle. Fluid-related information such as, for example, concentration of a blood component, may be estimated based on images of fluids in the receptacle.
