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Carotid Duplex


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.

Alternative Names

Scan - carotid duplex; Carotid ultrasound

How the test is performed

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.

How to prepare for the test

No preparation is necessary.

How the test will feel

The test is noninvasive and painless.

Why the test is performed

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

Normal Values

A normal result means there is no problem with the blood flow in the carotid arteries. The artery is free of any blockage, narrowing, or other problem.

Note: Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

An abnormal result means there are disturbances in the blood flow in the carotid arteries. This is a sign of atherosclerosis or blood vessel conditions.

Depending on the exact results, your doctor may want you to:

  • Follow a healthy diet and lifestyle to prevent atherosclerosis
  • Repeat the test again in the future
  • Have additional tests (such as cerebral angiography, CT angiography, and MR angiography)
  • Consider surgery

See the article on atherosclerosis for further treatment information.

What the risks are

There are no specific risks related to having this procedure.


U.S. Preventive Services Task Force. Screening for carotid artery stenosis: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2007;147(12):854-859.

Meschia JF, Brott TG, Hobson RW 2nd. Diagnosis and invasive management of carotid atherosclerotic stenosis. Mayo Clin Proc. 2007;82(7):851-858.

Review Date: 5/12/2009

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Information developed by A.D.A.M., Inc. regarding tests and test results may not directly correspond with information provided by UCSF Medical Center. Please discuss with your doctor any questions or concerns you may have.