A diagnostic ultrasound system for measuring regurgitant flow comprising: an ultrasound probe having a transducer array configured for transmitting ultrasonic energy to and receiving ultrasonic echoes from a location of regurgitant flow in a body; an image processor, responsive to received echoes, configured for producing an ultrasound image of the location of regurgitant flow; a wall filter, responsive to received echoes, having a response characteristic extending between upper and lower sampling rates, wherein the response characteristic of the wall filter peaks in the range of 1⁄2 to 2/3 of a Nyquist limit a Doppler processor responsive to echo signals passed by the wall filter configured for producing Doppler ultrasound measurements of blood flow velocity in the vicinity of the location of regurgitant flow; a flow quantification processor configured to produce a measurement of a flow velocity field in the vicinity of the location of regurgitant flow; and a display device, coupled to the image processor and the flow quantification processor, configured for displaying the ultrasound image of the location of regurgitant flow and a flow measurement derived from the flow quantification processor measurement; wherein the flow quantification processor is further configured to refine a location of a regurgitant orifice by - initializing, based on assumptions about the regurgitant flow, including the location of the regurgitant orifice, the value of one or more parameters of a flow velocity field model, - adjusting the flow velocity field model based on physical and operating factors of the ultrasound system, - determining, using the adjusted flow velocity field model, expected blood flow velocity values, - comparing the expected blood flow velocity values with the Doppler ultrasound measurements of blood flow velocity to determine an error term, and - iteratively adjusting the parameters of the flow velocity field model so as to cause a reduction of the error term. an ultrasound probe having a transducer array configured for transmitting ultrasonic energy to and receiving ultrasonic echoes from a location of regurgitant flow in a body; an image processor, responsive to received echoes, configured for producing an ultrasound image of the location of regurgitant flow; a wall filter, responsive to received echoes, having a response characteristic extending between upper and lower sampling rates, wherein the response characteristic of the wall filter peaks in the range of 1⁄2 to 2/3 of a Nyquist limit a Doppler processor responsive to echo signals passed by the wall filter configured for producing Doppler ultrasound measurements of blood flow velocity in the vicinity of the location of regurgitant flow; a flow quantification processor configured to produce a measurement of a flow velocity field in the vicinity of the location of regurgitant flow; and a display device, coupled to the image processor and the flow quantification processor, configured for displaying the ultrasound image of the location of regurgitant flow and a flow measurement derived from the flow quantification processor measurement; wherein the flow quantification processor is further configured to refine a location of a regurgitant orifice by - initializing, based on assumptions about the regurgitant flow, including the location of the regurgitant orifice, the value of one or more parameters of a flow velocity field model, - adjusting the flow velocity field model based on physical and operating factors of the ultrasound system, - determining, using the adjusted flow velocity field model, expected blood flow velocity values, - comparing the expected blood flow velocity values with the Doppler ultrasound measurements of blood flow velocity to determine an error term, and - iteratively adjusting the parameters of the flow velocity field model so as to cause a reduction of the error term. - initializing, based on assumptions about the regurgitant flow, including the location of the regurgitant orifice, the value of one or more parameters of a flow velocity field model, - adjusting the flow velocity field model based on physical and operating factors of the ultrasound system, - determining, using the adjusted flow velocity field model, expected blood flow velocity values, - comparing the expected blood flow velocity values with the Doppler ultrasound measurements of blood flow velocity to determine an error term, and - iteratively adjusting the parameters of the flow velocity field model so as to cause a reduction of the error term.