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Ankle-brachial index


The ankle-brachial index test is a quick, non-invasive way to assess your risk for peripheral artery disease, a condition in which the arteries in your legs and ankles are narrowed. People with peripheral artery disease are at a higher risk of heart attack, stroke and poor circulation.

The ankle-brachial index test compares your blood pressure measured at your ankle with your blood pressure measured at your arm. A low ankle-brachial index number can indicate narrowing or blockage of the arteries in your legs, leading to circulatory problems, heart disease or stroke.

Why it's done

Ask your doctor if you should have this test if you are age 50 or older and have any of these risk factors for peripheral artery disease:


The test may not adequately measure the ankle-brachial index if you have severe diabetes or calcified arteries with significant blockage. Instead, your doctor may need to read your blood pressure at your big toe to get an accurate index number if you have either of these conditions.

How you prepare

Generally, you won't need to follow any special instructions before your appointment to have an ankle-brachial index test performed.

What you can expect

You lie on a table on your back, and your doctor measures your blood pressure in both your arms using an inflatable cuff. Then, your doctor measures the blood pressure in two positions in your left ankle using the inflatable cuff and a hand-held Doppler device that your doctor will press on your skin. The Doppler device lets your doctor hear your pulse in your ankle arteries after the cuff is deflated.

The procedure for performing an ankle-brachial index test may vary slightly, based on your doctor's preference.

Having an ankle-brachial index test is painless and similar to getting your blood pressure taken in a routine visit to your doctor. You may feel some pressure on your arm or ankle when the cuff inflates to read your blood pressure.


When the ankle-brachial index test is complete, your doctor calculates your ankle-brachial index by dividing the higher of the two blood pressure measurements at your arms by the higher of the two blood pressure measurements at the arteries near your ankle. Based on the number your doctor calculates, your ankle-brachial index may indicate:

Some doctors recommend a series of three tests, including the ankle-brachial index test, to thoroughly check for cardiovascular disease. The two other tests include an abdominal ultrasound to screen for potential abdominal aortic aneurysm and a carotid artery ultrasound to check for blockage in the artery in your neck. Talk to your doctor to see if receiving all three of these tests is necessary for you.