Carotid Duplex Scanning

What is carotid duplex scanning?

Carotid duplex scanning is a noninvasive ultrasound method that measures blood flow through the carotid arteries, the large arteries that run from the heart through the neck to the brain.

Carotid duplex scanning is often the first test done to assess stroke risk, and often helps the medical team decide what other tests may be needed to determine a diagnosis and treatment plan.

Your physician may order carotid duplex scanning to evaluate symptoms including:

What happens during carotid duplex scanning?

During carotid duplex scanning, the patient lies flat on an examination table with their neck slightly extended.

A vascular technologist applies a warm, clear gel to the neck and places a small microphone-like device, known as a transducer, along both the sides of the neck, following the carotid arteries.

Sound waves are bounced off the blood vessels and tissues of the neck to create a two-dimensional image of the arteries. Duplex scanning is used to measure blood flow at many points in the blood vessel at one time. The measurements provide the medical team a clear view of any arterial blockage, as well as giving them information on how fast blood is flowing through the blood vessel.

How long will the procedure take?

The exam takes approximately 15 to 30 minutes. If it is being done on a patient who is not admitted to the hospital (outpatient), they should plan to be at Cedars-Sinai for at least an hour.

Does carotid duplex scanning cause any pain or discomfort?

Although the patient may hear unusual sounds during the procedure, it is painless.

As the vascular technologist moves the transducer along the skin, some mild pressure may be felt, and some patients do get a little uncomfortable from lying still for the length of the test.

What should you do prior to the test?

There is no preparation necessary for this test. Patients are encouraged to dress comfortably.

What should you expect after the test?

If it is being done on an outpatient, the patient is free to go home. The physician will follow up with results and explain what they mean.

For an appointment, a second opinion or more information, please call 1-800-CEDARS-1 (1-800-233-2771) or email us at