A Doppler ultrasound test uses reflected sound waves to see how blood flows through a blood vessel. During pregnancy, Doppler ultrasound may be used to look at blood flow in an unborn baby (fetus) to check the health of the fetus.
Doppler studies can also be applied in suspected venous thrombosis, vascular diseases, as well as general vascular assessment.
Color Doppler uses standard ultrasound methods to produce a picture of a blood vessel. Also, a computer converts the Doppler sounds into colors that are overlaid on the image of the blood vessel and that represent the speed and direction of blood flow through the vessel.