What is an ankle-brachial index?
The ankle-brachial index (ABI) is a measurement that is useful to your physician in evaluating the adequacy of the circulation in your legs. It can also be used to follow the improvement or worsening of leg circulation over time. To obtain the ABI, your physician measures your blood pressure in your ankle and in your arm. Your physician will compare the two numbers by forming a ratio to determine your ABI.
Normally, the blood pressures in your ankle and arm should be about equal. But if your ankle pressures are lower than your arm pressures, your leg arteries are probably narrowed.
To perform the ABI, your physician may use an ordinary blood pressure cuff and an ultrasound device. The ABI helps your physician diagnose arterial disease in the legs, but it is a general test and it does not specifically identify which arteries are blocked.
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Revised September 4, 2009