South Bay Cardiovascular Center
You have two common carotid arteries—one on each side of your neck—that divide into internal and external carotid arteries. Figure A shows the location of the right carotid artery in the head and neck. Figure B is a cross-section of a normal carotid artery that has normal blood flow. Figure C shows a carotid artery that has plaque buildup and reduced blood flow.
Too much plaque in a carotid artery can cause a stroke. The plaque can slow down or block the flow of blood through the artery, allowing a blood clot to form. A piece of the blood clot can break off and get stuck in the artery, blocking blood flow to the brain. This is what causes a stroke.
Carotid ultrasound checks for plaque buildup in the carotid arteries. Plaque can narrow or block your carotid arteries, preventing oxygen-rich blood from reaching your brain.
Your doctor may recommend a carotid ultrasound if you:
Your doctor also may recommend a carotid ultrasound if he or she suspects you may have:
A carotid ultrasound also may be done to see whether carotid artery surgery, also called carotid endarterectomy, has restored normal blood flow through your carotid artery.
If you had a procedure called carotid stenting, you may have carotid ultrasound afterward to check the position of the stent put in your carotid artery. (The stent, a small mesh tube, helps prevent the artery from becoming narrowed or blocked again.)
Sometimes carotid ultrasound is used as a preventive screening test in people who have medical conditions that increase their risk of stroke, including high blood pressure and diabetes.
People who have these conditions may benefit from having their carotid arteries checked regularly, even if they show no signs of plaque buildup.
Carotid ultrasound is a painless test, and typically there is little to do in advance. Your doctor will tell you how to prepare for your carotid ultrasound.
Carotid ultrasound usually is done in a doctor's office or hospital. The test is painless and often doesn't take more than 30 minutes.
The ultrasound machine includes a computer, a video screen, and a transducer. A transducer is a hand-held device that sends and receives ultrasound waves into and from the body.
You will lie on your back on an exam table for the test. Your technician or doctor will put a gel on your neck where your carotid arteries are located. This gel helps the ultrasound waves reach the arteries better.
Your technician or doctor will put the transducer against different spots on your neck and move it back and forth. The transducer gives off ultrasound waves and detects their echoes after they bounce off the artery walls and blood cells. Ultrasound waves can't be heard by the human ear.
A computer uses the echoes to create and record pictures of the insides of the arteries (usually in black and white) and your blood flowing through them (usually in color; this is the Doppler ultrasound). A video screen displays these live images for your doctor to review.
Figure A shows how the ultrasound probe (transducer) is placed over the carotid artery. Figure B is a color ultrasound image showing blood flow (the red color in the image) in the carotid artery. Figure C is a waveform image showing the sound of flowing blood in the carotid artery.
You usually don't have to take any special steps after a carotid ultrasound. You should be able to return to normal activities right away.
Often, your doctor will be able to tell you the results of the carotid ultrasound when it occurs or soon afterward.
A carotid ultrasound can show whether plaque buildup has narrowed one or both of your carotid arteries and reduced blood flow to your brain.
If plaque has narrowed your carotid arteries, you may be at risk of having a stroke. That risk depends on how much of your artery is blocked and how much blood flow is restricted.
To reduce your risk for stroke, your doctor may recommend medical or surgical treatments to reduce or remove the plaque buildup in your carotid arteries.
There are no risks linked to having a carotid ultrasound, because the test uses harmless sound waves. These are the same type of sound waves that doctors use to record pictures of fetuses in pregnant women.
Reference: The National Heart, Lung and Blood Institute
Last Updated May 1, 2017