Limb plethysmography is a test that compares blood pressure in the legs and arms. It is usually done to check for blood flow blockages in the legs.

This test may be done in the health care provider's office or in a hospital. You will be asked to lie in a partially propped-up position.

Three blood pressure cuffs are wrapped snugly around your arm and leg. The health care provider inflates the cuffs and a machine called a plethysmograph measures the pulses from each cuff. The test records the maximum pressure produced when the heart contracts (systolic blood pressure).

Any differences between the pulses are noted. If there is there is a decrease in the pulse between the arm and leg, it may indicate a blockage.

When the test is complete, the blood pressure cuffs are removed.

Do not smoke for at least 30 minutes before the test. You will be asked to remove all clothing from the arm and leg being tested.

You should not have much discomfort with this test. You should only feel the pressure of the blood pressure cuff.

The test is done to help rule out blocked arteries in the arms or legs.

There should be less than 20 mmHg difference in the systolic blood pressure of the leg compared with that of the arm.

Abnormal results may be due to:

• Arterial occlusive disease
• Blood clots
• Blood vessel changes due to diabetes
• Injury to an artery
• Other blood vessel disease (vascular disease)

Other conditions under which the test may be performed:

• Deep venous thrombosis

There are no risks.

The test is not as accurate as an arteriography. Plethysmography may be done for very ill patients who cannot travel to the arteriography lab. This test can be used to screen for vascular disease or to follow up earlier abnormal tests.

Gerhard-Herman M. Guidelines for noninvasive vascular laboratory testing: a report from the American Society of Echocardiography and the Society of Vascular Medicine and Biology. J Am Soc Echocardiogr. 01 Aug 2006; 19(8): 955-72.