A test system and method for evaluating the efficiency of the venous pump in leg muscles and for identifying incompetent venous valves. The test system comprises a legging having inflatable bladders, a manifold and a system controller. A pressurized inflation source is provided which is in fluid communication with the manifold and the legging. The controller sequences valves within the manifold to inflate and deflate the bladders of the legging. The test system further includes a Doppler blood flow sensor interfaced to the controller. The sensor is configured with a housing which contains a rotatable disk, upon which two pairs of crystals are disposed. The sensor housing is secured a leg of a patient proximate a blood vessel in which blood flow is to be measured. The patient is positioned on a reclinable test station, upon which the controller and manifold may be mounted. The maximum volume of venous blood output from the leg is measured and the venous output flow is subsequently measured after the bladders are sequentially inflated above a first location on the leg of the patient. Reduced venous output flow from the maximum volume output indicates reflux and identifies the location of an incompetent valve.