Carotid ultrasound is a painless imaging test that uses high-frequency sound waves to create pictures of the inside of your carotid arteries. Your carotid arteries are the major blood vessels that supply oxygen-rich blood to your brain. Carotid ultrasound can help detect plaque buildup in one or both of your carotid arteries. It can also see whether the buildup is blocking blood flow to the brain. If combined with Doppler ultrasound, this test can also show how blood is moving through your arteries. Carotid ultrasound is usually done in a doctor’s office or hospital. This test uses an ultrasound machine, which includes a computer, a screen, and a transducer. The transducer is a handheld device that sends and receives sound waves.

You will lie on your back on an exam table for your test. The ultrasound technician will put gel on your neck where your carotid arteries are located. The gel helps the sound waves reach your arteries. The technician will move the transducer against different areas on your neck. The transducer will detect the sound waves after they have bounced off your artery walls and blood cells. A computer will use the sound waves to create and record pictures of the inside of your carotid arteries and to show how blood is flowing in your carotid arteries. Test results will help your doctor plan treatment to remove or stabilize plaque and help prevent a stroke.

Carotid ultrasound has no risks because the test uses harmless sound waves. They are the same type of sound waves that doctors use to create and record pictures of a baby inside a pregnant woman.