A Doppler ultrasound test uses reflected sound waves to evaluate blood as it flows through a blood vessel. It helps doctors evaluate blood flow through the major arteries and veins of the arms, legs, and neck. A Carotid Doppler can show blocked or reduced blood flow through narrowing in the major arteries of the neck that could cause a stroke.
WebMD. (2009, January 05). Retrieved from http://www.webmd.com/a-to-z-guides/doppler-ultrasound