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Duplex ultrasoundDefinitionA duplex ultrasound is a test to see how blood moves through your arteries and veins. The test combines traditional ultrasound with Doppler ultrasonography. Regular ultrasound uses sound waves that bounce of blood vessels to create pictures. Doppler looks at how sound waves reflect off moving objects, such as blood. There are different types of duplex ultrasound exams. Some include:
Alternative NamesVascular ultrasoundHow the Test is PerformedThe 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 move better. A wand, called a transducer, is moved over the area being tested. This wand sends out the sounds 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 bounce and 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 TestUsually, 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 FeelYou may feel some pressure as the wand is moved over the body, but there is usually no discomfort. Why the Test is PerformedDuplex 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 ResultsA 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 MeanAn 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. RisksThere are no risks. ConsiderationsCigarette smoking may alter the results of an ultrasound of the arms and legs because nicotine can cause the arteries to constrict (shrink). ReferencesMarx J. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th ed. St. Louis, Mo: Mosby; 2002:377, 1192. Grainger RC, Allison D, Adam, Dixon AK. Diagnostic Radiology: A Textbook of Medical Imaging. 4th ed. Orlando, Fl: Churchill Livingstone; 2001:60, 1684.
Review Date:
9/15/2006 Reviewed By: Cameron Akbari, MD, MBA, FACS, Senior Attending, Vascular Surgery Director, Vascular Diagnostic Laboratory, Washington Hospital Center, Washington, DC. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997-
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