The ankle-brachial index test is a quick, noninvasive way to check your risk of peripheral artery disease (PAD). Peripheral artery disease is a condition in which the arteries in your legs or arms are narrowed or blocked. People with peripheral artery disease are at a high risk of heart attack, stroke, poor circulation and leg pain.
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. The ankle-brachial index test is sometimes recommended as part of a series of three tests, including the carotid ultrasound and abdominal ultrasound, to check for blocked or narrowed arteries.
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:
- Being a current or former smoker
- Overweight (a body mass index of 25 or greater)
- High blood pressure
- High cholesterol
If you’ve already been diagnosed with peripheral artery disease, your doctor may recommend having an ankle-brachial index test to see if your treatment is working or if your condition has worsened.
For most people, there are no physical risks involved in an ankle-brachial index test. You may feel some discomfort when the blood pressure cuffs inflate on your arm and ankle, but this discomfort is temporary and should stop when the air is released from the cuff.
If you have severe leg or arm pain, your doctor may not recommend an ankle-brachial index test. Instead of an ankle-brachial index test, your doctor may recommend a different imaging test of the arteries in your legs.
Generally, you won’t need to follow any special instructions before your appointment to have an ankle-brachial index test performed. You may want to wear loose, comfortable clothing that allows the technician performing your ankle-brachial index test to easily place a blood pressure cuff on your ankle and upper arm.
What to Expect
We will have you change into a gown or comfortable clothing. Your shoes and socks will need to be removed. Blood pressure cuffs will be placed on both arms, upper thigh, calves, ankles and big toes and you will lie flat on a table while blood pressures are checked in each cuff individually. This part of the test takes about 25 minutes. If you are able, you will be asked to walk on a treadmill for about 5 minutes. Then blood pressures are rechecked in one of the arm cuffs as well as both ankles. This may be repeated several times and can take up to 35 minutes.
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 when the cuff inflates to read your blood pressure.
After the test
The ankle-brachial index test will take approximately an hour, and there are no special precautions you’ll need to take following the test. Your doctor will discuss your test results with you at a future appointment.