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Alternative Names Return to topVascular ultrasound; Peripheral vascular ultrasound
Definition Return to top
A duplex ultrasound is a test to see how blood moves through your arteries and veins.
How the Test is Performed Return to top
The test combines traditional ultrasound with Doppler ultrasonography. Regular ultrasound uses sound waves that bounce off blood vessels to create pictures. Doppler ultrasound records sound waves reflecting off moving objects, such as blood, to measure their speed and other aspects of how they flow.
There are different types of duplex ultrasound exams. Some include:
The test is done in the ultrasound or radiology department.
You may need to wear a medical gown. You will lie down on a table, and the ultrasound technician will spread a gel over the area being tested. The gel helps the sound waves get into your tissues.
A wand, called a transducer, is moved over the area being tested. This wand sends out the sound waves.
You need to stay still during the exam. You may be asked to lie in different body positions, or to take a deep breath and hold it.
A computer measures how the sound waves reflect back, and changes the sound waves into pictures. The Doppler creates a "swishing" sound, which is the sound of your blood moving through the arteries and veins.
Sometimes during a duplex ultrasound, the health care provider may calculate an ankle-brachial (ABI) index. You will need to wear blood pressure cuffs on your arms and legs for this test.
The ABI number is obtained by dividing the blood pressure in the ankle by the blood pressure in the arm. A value of 0.9 or greater is normal. An ABI of less than 0.5 is linked to peripheral vascular (arterial) disease.
How to Prepare for the Test Return to top
Usually, there is no preparation for a duplex ultrasound.
If you are having an ultrasound of your stomach area, you may be asked not to eat or drink after midnight. Tell the person doing the ultrasound exam if you are taking any medicines, such as blood thinners, that might affect the results of the test.
How the Test Will Feel Return to top
You may feel some pressure as the wand is moved over the body, but there is usually no discomfort.
Why the Test is Performed Return to top
Duplex ultrasound is a less-invasive option to arteriography and venography. A duplex ultrasound can show how blood flows to many parts of the body. It can also tell the width of a blood vessel and reveal any blockages.
A duplex ultrasound can help diagnose the following conditions:
A renal duplex ultrasound can also be used after transplant surgery to see how well a new kidney is working.
Normal Results Return to top
A normal result is normal blood flow through the veins and arteries. There is normal blood pressure and no sign of a narrowing or blockage of a blood vessel.
What Abnormal Results Mean Return to top
An abnormal result depends on the specific area being examined. An abnormal result may be due to a blood clot or plaque build-up in a blood vessel.
Risks Return to top
There are no risks.
Considerations Return to top
Cigarette smoking may change the results of an ultrasound of the arms and legs because nicotine can cause the arteries to shrink (constrict).
References Return to top
Marx J. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 6th ed. St. Louis, Mo: Mosby; 2006. 541, 1346.
Grainger RC, Allison D, Adam, Dixon AK. Diagnostic Radiology: A Textbook of Medical Imaging. 4th ed. Orlando, Fl: Churchill Livingstone; 2001:60, 1684.Update Date: 4/22/2008 Updated by: David C. Dugdale, III., MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.