Ankle Brachial Index (ABI)

What is an ABI?

An ankle brachia! index (ABI) is a test that can diagnose peripheral vascular disease (PVD). The ABI measures blood pressure in your ankle as well as in your arm. Your doctor compares the blood pressure readings in your arms and the readings in your legs. In this way the ABI can reveal blocked blood flow in the arteries of your legs.

The ABI is usually a good indicator of:

Sometimes your doctor orders other tests that are done at the same time as the ABI. One of these tests is a Doppler ultrasound. An ultrasound uses sound waves that bounce off the blood vessels and other tissues in your leg or foot. In this way the ultrasound can measure the amount of blood flowing through the arteries in that specific location.

Sometimes an ABI is done along with a stress test (or exercise test). This is recommended especially if the doctor gets abnormal ABI readings. In these cases, the doctor performs an ABI both before and after the stress test.

To learn more about a stress test or a Doppler ultrasound, go to those entries in the Tests section.

What can I expect?

When you have an ankle brachia! index (ABI), you undress, put on a hospital gown, and lie on an exam table. A blood pressure cuff is put on each arm, and cuffs are placed at four locations on your legs. The cuffs are inflated and deflated-first on the arms, then on the legs. When a Doppler ultrasound is also done, gel is applied to your skin-typically on your feet. After the leg cuffs are deflated, the doctor moves a pen-like instrument (called a transducer) over your skin to measure blood flow in the arteries. The ABI, like a regular blood pressure test, is generally a simple and painless test.