Duplex ultrasound of the extremities looks at the arms or legs.
Renal duplex ultrasound examines the kidneys and their blood vessels.
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. 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.
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.
Sometimes during a duplex ultrasound of the legs, 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.
How to Prepare for the Test
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. These might affect the results of the test.
How the Test will Feel
You may feel some pressure as the wand is moved over the body, but there is no discomfort most of the time.
Why the Test is Performed
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. Duplex ultrasound is a less invasive option than arteriography and venography.
A duplex ultrasound can help diagnose the following conditions:
Deepak Sudheendra, MD, Assistant Professor of Interventional Radiology & Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.