Carotid duplex is a procedure that uses ultrasound to look for blood clots, plaque buildup, and other blood flow problems in the carotid arteries. The carotid arteries are located in the neck. They supply blood to the brain.

The test checks blood flow in the carotid arteries. It can detect:

• Blood clotting (thrombosis)
• Narrowing in the arteries (stenosis)
• Other causes of blockage in the carotid arteries

Your doctor may order this test if you have had a:

• Stroke
• Transient ischemic attack (TIA)

You may also have this test:

• If your doctor hears an abnormal sound called a bruit over the carotid neck arteries
• As a follow-up test after a previous carotid duplex test

The test is done in a vascular lab or radiology department of a hospital. You will be asked to lay on your back. Your head will be supported to prevent it from moving.

The health care provider applies a water-soluble gel on your skin and gently runs a handheld device called a transducer over the area of the carotid arteries in your neck. The devices sends high-frequency sound waves to the arteries in your neck. The gel helps transmit the sound waves. The sound waves bounce off the blood vessels and form images of their structure.

No preparation is necessary.

The test is noninvasive and painless.