A mains electricity (AC-powered) device assembly consisting of a desktop unit, a graphical display unit and an attached probe or interchangeable probes, designed to noninvasively locate and assess the extent of vascular flow restriction (e.g., clots, stenosis, mechanical damage) by measuring blood flow rate using ultrasound/Doppler/transit time technology. Clinical applications include venous/arterial flow screening (e.g., assessment of air embolism, atherosclerosis, varicose veins, venous thrombosis), ankle pressure index, and/or blood flow wave form recording.