Duplex/doppler ultrasound exam of extremity, vascular ultrasound

Definition
This test examines the blood flow in the major arteries and veins in the arms and legs with the use of ultrasound (high-frequency sound waves). The test combines Doppler ultrasonography, which uses audio measurements to “hear” and measure the blood flow and duplex ultrasonography, which provides a visual image.

How the test is performed

The test is done in the ultrasound or radiology department.

To examine the veins: A water-soluble gel is placed on the transducer (a hand-held device that directs the high-frequency sound waves to the artery or vein being tested) and on the skin over the veins of the limb being tested. Blood flow on a Doppler examination creates a “swishing” sound. Both the superficial (close to the skin) and deep veins are evaluated. Visual images are also obtained.

To examine the arteries: Blood pressure cuffs are placed around the thigh, calf, and ankle to examine the legs. To test the arms, the blood pressure cuffs are placed at different points along the arm. A conductive paste is applied to the skin over the arteries being examined. The cuff will be inflated above the normal systolic blood pressure for the extremity.

The transducer is placed near the cuff and the pressure in the cuff is released slowly. When the “swishing” sound is detected, the measurement is recorded as the blood pressure. This is repeated for each cuff. Visual images may also be obtained.

How to prepare for the test
Remove clothing from the extremity. Inform the heath care provider of any medications that you are taking, especially blood pressure and vascular medications which may interfere with the results.

For infants and children:
The preparation you can provide for this procedure depends on your child’s age and experience. For specific information regarding how you can prepare your child, see the following topics:

     
  • Infant test or procedure preparation (birth to 1 year)  
  • Toddler test or procedure preparation (1 to 3 years)  
  • Preschooler test or procedure preparation (3 to 6 years)  
  • Schoolage test or procedure preparation (6 to 12 years)  
  • Adolescent test or procedure preparation (12 to 18 years)

How the test will feel
There is no discomfort from the ultrasound device. You will feel tightening in your arm or leg if the pressure cuff is used. This pressure will last only a few moments.

Why the test is performed
This test is done as an alternative to arteriography and venography, both invasive procedures with risks. It may help diagnose a blood clot or venous insufficiency, arterial occlusion (closing), abnormalities in the arterial blood flow caused by a narrowing, and to evaluate trauma to the arteries. The test may also be used to monitor arterial reconstruction and bypass grafts.

Normal Values

The veins show normal flow, and the deep veins show flow that varies with breathing. The veins should be fully compressible and have no internal clots.

The arteries have normal systolic and diastolic components on the ultrasound, which correspond to the beating and resting of the heart. There is normal blood pressure and no sign of a narrowing or closure. The normal ankle-to-brachial arterial blood pressure index (ratio of systolic blood pressures) is 0.85 or greater.

What abnormal results mean

     
  • In the veins:       o Venous occlusion (closing of vein)       o Blood clots  
  • In the arteries:       o Arterial occlusive disease       o Spastic arterial disease (arterial contractions brought on by cold or emotion)       o Embolic arterial occlusion (obstruction in the artery by a body such as a blood clot, fat globules, or air bubbles.)

What the risks are
There are no risks from using ultrasound waves on the extremities.

Special considerations
Cigarette smoking may alter the results of the test because nicotine can cause the arteries in the extremities to constrict.

Johns Hopkins patient information

Last revised: December 6, 2012
by Simon D. Mitin, M.D.

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