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Blood flow studies
Alternative namesDuplex/Doppler ultrasound
DefinitionBlood flow studies measure blood flow and pressure. A duplex study uses Doppler ultrasound to estimate blood flow through arteries or veins. Plethysmography measures changes in blood volume in a blood vessel.
How the test is performed
For the Duplex/Doppler ultrasound:
How to prepare for the testClothing over the extremity being tested will be removed just before the test. Medications being used that can alter blood flow will be recorded before the test. In general, there is no other special preparation necessary for these tests.
For infants and children:
The preparation you can provide for this test depends on your child's age and experience. For specific information regarding how you can prepare your child, see the following topics:
How the test will feelFor the 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 performedThese are noninvasive (external) tests used to determine if there is significant disease in either arteries or veins, if adequate blood is reaching an extremity, to evaluate trauma to a blood vessel, or to monitor patients with arterial reconstruction or grafts. These tests can also detect blood clots .
Normal ValuesAs part of a duplex ultrasound, the doctor may calculate an ABI or ankle-brachial index. This number is obtained by dividing the Doppler or systolic pressure of the ankle by the pressure in the arm. A value of 0.9 or greater is normal. Your doctor will also evaluate the flow of blood in the vessels with the ultrasound.
What abnormal results mean
An ABI of less than 0.5 is associated with peripheral vascular (arterial) disease .
Other abnormal blood flow patterns can be seen with:
What the risks areThere are no special risks associated with these tests.
Special considerationsMost Doppler ultrasounds use a duplex/Doppler probe to enable the technician to both view the vessels (regular ultrasound) as well as assess the blood flow through them (Doppler imaging).
Update Date: 10/29/2003Jeffrey Everett, M.D., Department of Surgery, University of Iowa, Iowa City, IA. Review provided by VeriMed Healthcare Network.
Last updated: Tue, 06 Jan 2009 00:20:03 GMT