A carotid ultrasound is a painless test that uses sound waves to the blood flow through the carotid arteries. There are two common carotid arteries, one on each side of the neck. The internal carotid arteries supply oxygen-rich blood to your brain. The external carotid arteries supply oxygen-rich blood to your face, scalp, and neck.
A carotid ultrasound tests for blocked or narrowed arteries, which can increase the risk of a stroke. The blocked or narrowed arteries are caused by a waxy substance called plaque, which can build up in the carotid arteries.
Different Types of Plaque
Plaque forms in the arteries and can eventually harden or rupture (break open).
Hardened plaque narrows the carotid arteries and reduces the flow of oxygen-rich blood to the brain. If it ruptures, a blood clot can form on its surface. A clot blocks either some or all of the blood flow through a carotid artery, which can cause a stroke.
A piece of plaque or a blood clot also can break away from the wall of the carotid artery. The plaque or clot can travel through the bloodstream and get stuck in one of the brain's smaller arteries. This can block blood flow in the artery and cause a stroke.
A carotid ultrasound views the structure of the carotid arteries. The test might include a Doppler ultrasound. Doppler ultrasound is a special test that shows the movement of blood through the blood vessels.
Why have it done?
A carotid ultrasound is performed to test for narrowed carotid arteries, which increase the risk of stroke.
Carotid arteries are usually narrowed by a buildup of plaque — made up of fat, cholesterol, calcium and other substances that circulate in the bloodstream. Early diagnosis and treatment of a narrowed carotid artery can decrease stroke risk.
Your doctor will recommend carotid ultrasound if you have transient ischemic attacks (TIAs) or certain types of stroke and may recommend a carotid ultrasound if you have medical conditions that increase the risk of stroke, including:
- High blood pressure
- High cholesterol
- Family history of stroke or heart disease
- Recent transient ischemic attack (TIA) or stroke
- Abnormal sound in carotid arteries (bruit), detected by your doctor using a stethoscope
- Coronary artery disease
How it works
A technician conducts the test with a small, hand-held device called a transducer. The transducer emits sound waves and records the echo as the waves bounce off tissues, organs and blood cells.
A computer translates the echoed sound waves into a live-action image on a monitor. The radiologist may use a Doppler ultrasound, which shows blood flowing through the arteries. In a Doppler ultrasound, the rate of blood flow is translated into a graph.
The test usually takes about 30 minutes.
During the procedure
The technician will apply a warm gel to your skin above the site of each carotid artery. The gel helps transmit the ultrasound waves back and forth. They then gently press the probe against the side of your neck. You shouldn't feel any discomfort during the procedure.
The doctor will explain to you what the carotid ultrasound revealed and what that means for you.
If the test reveals you're at risk of a stroke, your doctor may recommend the following therapies, depending on the severity of blockage in your arteries:
- Eat a healthy diet, including plenty of fruits, vegetables and whole-grain breads and cereals, and low saturated fat.
- Exercise regularly and maintain a healthy weight.
- Quit smoking if current smoker.
- Take medications to lower blood cholesterol and blood pressure or to prevent blood clots
- Have a surgical procedure to remove carotid artery plaques or to open up and support your carotid arteries.