What is a Doppler ultrasound? — A Doppler ultrasound is a test that uses sound waves to create pictures of the inside of the body. Doctors use this imaging test to check for problems in the heart or blood vessels. A Doppler ultrasound can also show how blood flows through the blood vessels.

There are different ways doctors can do a Doppler ultrasound. One type of Doppler ultrasound is used specifically to check blood flow through blood vessels. It uses color images to show blood flow. Doctors sometimes call this test a “duplex” ultrasound.

Why might my doctor order a Doppler ultrasound? — Your doctor might order a Doppler ultrasound to check for:

  • Atherosclerosis – In this condition, fatty clumps called “plaques” build up in the arteries and make them narrow or blocked (figure 1). Atherosclerosis can happen in different parts of the body, including the carotid arteries (figure 2) or arteries in the legs (figure 3).
  • A deep vein thrombosis (also called a “DVT”) – This is when a blood clot forms in a deep vein in the leg (figure 4).
  • Problems with how the leg veins are working – If the veins in the legs don’t work well, blood can collect in the legs.
  • An injury to an artery
  • Problems with the heart valves – To check how well the heart valves are working, doctors can do a Doppler ultrasound as part of another test called an echocardiogram. An echocardiogram (also called an “echo”) uses sound waves to create a picture of the heart as it beats (figure 5).

How do I prepare for a Doppler ultrasound? — You do not need to do anything special to prepare for this test.

What happens during a Doppler ultrasound? — The doctor, nurse, or technician will put a small amount of gel on the part of your body being checked. Then he or she will press a thick wand, called a “transducer,” against your skin. He or she will move the transducer around on your skin. Images will appear on a computer screen.

This test does not usually hurt, but people can feel pressure when the transducer presses against their skin.