Ultrasound is a test that uses sound waves to create detailed pictures of the inside of your body. Duplex ultrasound is a type of ultrasound that makes two kinds of images. First, it creates pictures of your blood vessels. Then, it makes graphs that show the speed and the direction of blood flow through the vessels. These images are viewed on a computer screen. No radiation or contrast fluid (dye) is used during the test. Ultrasound tests are safe to use during all stages of pregnancy.

Duplex ultrasound can help your doctor find problems with blood vessels. These problems may include:

• Carotid occlusive disease. These blocked or narrowed carotid arteries can lead to stroke.
• Peripheral artery disease (PAD). These blocked or narrowed arteries in the arm or leg can cause pain.
• Aneurysm. This is a ballooning out of a blood vessel wall.
• Dissection. This is a tear in the layers of a blood vessel wall.
• Deep vein thrombosis (DVT). This blood clot is in the deep veins of the arms or legs.
• Varicose veins. These swollen, twisted veins can be seen under the skin's surface.
• Abnormal blood flow. This is an abnormal increase or decrease of blood flow to an area of your body.

Duplex ultrasound can also help your doctor:

• Decide whether further testing is needed.
• Determine the best treatment plan for you.
• Get more information about your blood vessels before surgery is done.