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Blood flow studies


Blood flow studies measure blood flow and pressure.

Alternative Names

Duplex/Doppler ultrasound

How the Test is Performed

There are different methods for performing blood flow studies.

A duplex study uses Doppler ultrasound tomeasure blood flow through arteries or veins. Clothing is removed from the area being tested.A probe with a conductive gel (like vasoline) on the tip is placed on various points along the blood vessel in question. The information is relayed to the ultrasound monitor to be viewed and recorded.

Plethysmography measures changes in blood volume in a blood vessel.Blood pressure is first taken in both arms. Clothing is removed from the arm or leg being tested. You lie on your back. A blood pressure cuff is applied to the limb being tested. It is inflated until the beat of the pulseis no longer heard. Then the pressure is released from the cuff. The blood pressure is then recorded and the information isput into a computerto interpret the information.

The blood pressure cuff may be moved to other positions on the same or other extremities during the test. After the readings are taken, you may be re-tested while in another position such as sitting or standing.

How to Prepare for the Test

Clothing over the extremity will be removed just before the test. Tell the health care provider about medications you use, as they may alter blood flow.

How the Test Will Feel

Duringthe plethysmography, the blood pressure cuff will constrict the arm or leg, but there is no pain. The gel used for the duplex ultrasound may feel cold when it is placed on your skin.

Why the Test is Performed

These are noninvasive (external) tests that will tell your doctor if there is disease in the arteries or veins, or ifenough blood is reaching an arm or leg. The tests will look at injuries to blood vessels, orcheck patients with arterial reconstruction or grafts. These tests can alsofind blood clots.

Normal Results

As part of a duplex ultrasound, the doctor may calculate an ABI or ankle-brachial index. This number is obtained by dividing the pressurein the ankle by the pressure in the arm. A value of 0.9 or greater is normal. Your doctor will alsocheck the flow of blood in the vessels with the ultrasound.

What Abnormal Results Mean

An ABI of less than 0.5 is linked to peripheral vascular (arterial) disease.

Other abnormal blood flow patterns can be seen with:

These tests, or tests like them, may also be performed for additional conditions:


There are no special risks associated with these tests.


Duplex/Doppler probe lets the technician view the vessels as well asmeasure the blood flow through them.

Review Date: 8/11/2005
Reviewed By: Joseph P. Hart, M.D., Marco Polo Traveling Fellow c/o Department of Vascular Surgery, A. Z. St. Blasius Hospital (Belgium). Review provided by VeriMed Healthcare Network.
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