Carotid duplex

Alternative names
Scan - carotid duplex, Carotid ultrasound


Carotid duplex is a procedure that uses ultrasound to look for plaques, blood clots, or other problems with blood flow in the carotid artery walls and lumen (interior). The carotid arteries, located in the neck, supply blood to the brain.

How the test is performed

The test is done in the peripheral vascular lab or radiology department of a hospital. You are placed on your back and your head will be supported to prevent movement.

A water-soluble gel is placed on the skin where the transducer (a handheld device that directs the high-frequency sound waves to the arteries being tested) is to be placed. The gel helps transmit the sound to the skin surface. The ultrasound is turned on and images of the carotid arteries and pulse wave forms are obtained.

How to prepare for the test

No special preparation is necessary.

For infants and children:

The preparation you can provide for this test depends on your child’s age and experience. For specific information regarding how you can prepare your child, see the following topics:

  • Infant test/procedure preparation (birth to 1 year)  
  • Toddler test/procedure preparation (1 to 3 years)  
  • Preschooler test/procedure preparation (3 to 6 years)  
  • Schoolage test/procedure preparation (6 to 12 years)  
  • Adolescent test/procedure preparation (12 to 18 years)

How the test will feel
The test is noninvasive and painless.

Why the test is performed

The test assesses blood flow and is used to detect the conditions involving stenosis (narrowing and hardening), thrombosis (clotting), and other causes of obstruction in the carotid arteries.

Normal Values
The artery is free of any obstructions, stenosis, or thrombosis, and there is no flow abnormality. There is no turbulence or disruption in the arterial blood flow.

What abnormal results mean
There is a disturbance of the blood flow in the artery related to stenotic, obstructive, or thrombotic diseases (for example, atherosclerosis).

What the risks are
There are no specific risks related to this procedure.

Johns Hopkins patient information

Last revised: December 6, 2012
by Simon D. Mitin, M.D.

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