Carotid Duplex Sonography

Definition

Carotid duplex sonography, sometimes called carotid duplex ultrasound, is a non-invasive diagnostic procedure that allows a physician to see the structure of the carotid artery and the way blood is flowing through it.

Purpose

The common carotid arteries are a pair of arteries running along either side of the neck. Each carotid artery divides into an inner and an outer branch. The outer branch (also referred to as the external carotid artery) supplies blood to the neck and face. The inner branch (also referred to as the internal carotid artery) supplies blood to the brain. Sometimes plaque, which is a mixture of fat, cholesterol, and cellular debris, builds up in the inner lining of an artery. Carotid duplex sonography is used to determine whether the carotid artery is narrowed (a condition called stenosis) because of build-up of plaque on the inner walls of the artery. Plaque build-up and blockage of the inner branch of the carotid artery can cause stroke, brain damage, or death. Often carotid duplex sonography is performed because a physician hears abnormal noises when listening to the carotid artery with a stethoscope. These noises are made by blood pushing through a narrow spot in the carotid artery. Carotid duplex sonography allows the physician to see any blockage or structural abnormalities and to visualize blood flowing through the artery.

Precautions

Carotid duplex sonography is a very safe, risk-free procedure. The patient is not exposed to radiation. The procedure is non-invasive and painless; no dyes or contrast media are injected. No special precautions are necessary.

Description

Carotid duplex sonography uses two types of ultrasound simultaneously. Traditional ultrasound uses high frequency sound waves that bounce off stationary structures in the body, such as blood vessels, and create an image. Doppler ultrasound uses sound waves that reflect off moving objects, such as blood cells moving through the carotid artery. Doppler ultrasound creates an image showing how the blood is flowing through the artery. Duplex sonography exposes an artery to both types of sound waves simultaneously.

Carotid duplex sonography is performed in an outpatient setting, either at a freestanding diagnostic facility, hospital clinic, or physician's office. The individual is placed on a tilting bed. A gel is applied to the neck, and the ultrasound wand is pressed to the area of skin covered by the gel. A technician moves the ultrasound wand back and forth over the skin of the neck. The individual must not move during this phase of the procedure. Information from the reflected sound waves is fed into a computer that creates images of the blood vessel and blood flow. The process is then repeated on the other side of the neck. The procedure takes about 30 minutes and is completely painless.

Preparation

No special preparation is needed. Individuals will need to remove jewelry from the head and neck prior the procedure.

Aftercare

No special aftercare is needed. No disability or delayed recovery is expected from this procedure.

Complications

Complications are not expected from this procedure. The procedure is safe for people of all ages and for pregnant women.

Results

Ordinarily, the images produced during carotid duplex sonography will show whether there is a blockage or structural abnormality in the carotid artery. Sometimes calcium deposits in the wall of the artery make it difficult to evaluate the images produced. When the results are not conclusive, additional tests, such as CT scans, MRI scans, or angiography may be needed.

Health care team roles

Carotid duplex sonography is performed by a trained radiology technician and the results are evaluated by a radiologist experienced in analyzing ultrasound images.

Resources

ORGANIZATIONS

American College of Radiology. 1891 Preston White Drive, Reston, VA 20191. (703) 648-8900. http://www.act.org.

Radiological Society of North America. 820 Jorie Blvd., Oak Brook, IL 60523-2251. (630) 571-2670. http://www.rsna.org.

OTHER

Agency for Healthcare Research and Quality, U.S. Preventive Services Task Force. "Screening for Asymptomatic Carotid Stenosis." Guide to Clinical Preventive Services, 2nd ed. Electronic archive. 1996. http://www.ahrq.gov/clinic/cpsix.htm (November 8, 2005).

Nadalo, Lennard A., and Michelle C. Walters. "Carotid Artery, Stenosis." eMedicine.com. February 22, 2005. http://www.emedicine.com/radio/topic/133.htm (November 8, 2005).

Radiological Society of North America. RadiologyInfo. "Carotid Ultrasound Imaging." November 3, 2004. http://www.radiologyinfo.org/content/us-carotid.htm (November 19, 2005).

Society for Vascular Surgery. "Duplex Ultrasound." Vascular Web. February 5, 2005. http://www.vascularweb.org/_CONTRIBUTION_PAGES/Patient_Information/NorthPoint/Duplex_Ultrasound.html (November 19, 2005).