Ankle-Brachial Index (ABI)

The illustration shows the ABI test. The ABI compares blood pressure in the ankle to blood pressure in the arm. As the cuff deflates, the blood pressure in the arteries is recorded.

A test called an ankle-brachial index or ABI is used to diagnose Peripheral Artery Disease. The ABI compares blood pressure in your ankle to blood pressure in your arm. This test shows how well blood is flowing in your limbs. ABI can show whether Peripheral Artery Disease (P.A.D.) is affecting your limbs, but it won’t show which blood vessels are narrowed or blocked..

A normal ABI result is 1.0 or greater (with a range of 0.90 to 1.30). The test takes about 10 to 15 minutes to measure both arms and both ankles. This test may be done yearly to see whether P.A.D. is getting worse.

A resting ankle-brachial index of less than 1 is abnormal. If the ABI is:

• Less than 0.95, significant narrowing of one or more blood vessels in the legs is indicated.
• Less than 0.8, pain in the foot, leg, or buttock may occur during exercise.
• Less than 0.4, symptoms may occur when at rest.
• 0.25 or below, severe limb-threatening PAD is probably present.

You may experience leg pain during the treadmill portion of the test if you have peripheral arterial disease (PAD).

Undiagnosed arterial disease in the arms can cause inaccurate test results.

A very abnormal ABI test result may require more testing to determine the location and severity of peripheral artery disease that might be present.