In most cases, the patient lies on his back during a carotid artery ultrasound, explains Mayo Clinic. The ultrasound technician applies a warm gel to the skin overlying each carotid artery, then gently presses the transducer against the patient's neck. This produces an image on the monitor that shows the flow of blood through the arteries. The procedure is not painful or uncomfortable and usually lasts about 30 minutes.
A carotid ultrasound allows a doctor to see if the patient's carotid arteries are narrowed, states Mayo Clinic. This type of narrowing is usually the result of plaque buildup from fat, cholesterol, calcium and other substances circulating in the bloodstream. Patients with narrowing of the carotid arteries are at increased risk of a stroke. Early diagnosis of the condition allows medical treatment that reduces the patient's risk. Doctors typically recommend an ultrasound for patients with a history of strokes, transient ischemic attacks, known as TIAs, or of medical conditions that increase the risk of stroke, such as high blood pressure, high cholesterol and coronary artery disease.
Other reasons a doctor may order a carotid ultrasound are to evaluate blood flow through the arteries after surgery to remove plaque buildup, to evaluate stent placement in the artery, to locate blood clots that may block the artery, or to detect other abnormalities that affect the flow of blood, according to Mayo Clinic.