What is an ankle-brachial index?
An ankle-brachial index (ABI) is a noninvasive screening test designed to detect arterial insufficiency, which is reduced blood flow through the arteries in your arms and legs. An ABI test helps your doctor determine whether narrowing (or another restriction) in an artery or blood vessel is reducing blood flow to your extremities and helps identify the location and how serious it is.
Why it’s done
The ABI test helps detect cardiovascular conditions, primarily peripheral artery disease (PAD). Your doctor may recommend an ABI test if you have risk factors for PAD. Risk factors may include:
- Age 65 or older
- Type 2 diabetes
- A family history of PAD, heart disease or stroke
- High blood pressure or high cholesterol
- A history of smoking, or using other tobacco products
Your doctor may also recommend an ABI test if you have claudication, which is pain in your calf, hips or thighs that occurs when you walk or move but goes away after you rest. Claudication is often related to PAD.
How to prepare for an ankle-brachial index test
Wear loose, comfortable clothing to your test. Shorts can make it easier for your healthcare provider to put on and remove the blood pressure cuff from your lower calf. Continue to take any medication as prescribed unless your doctor says otherwise. You won’t be able to have an ABI test if you have a fracture or wound on your arms or legs, so talk to your doctor if you’ve experienced a recent injury.
What to expect during an ankle-brachial index
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Before the test
Before the test
On the day of the test, the healthcare provider performing the test will review your medical history. You will lie on your back 10 to 30 minutes before the test. -
During the test
During the test
An ABI test measures your systolic blood pressure, a measurement of how much pressure blood places on your artery walls as your heart contracts.
During the test, your systolic blood pressure will be measured in both of your arms and your ankles.
Each time your blood pressure is taken, your provider will place a cuff around your arm or ankle. After inflating the cuff, they will place a small ultrasound device against your skin to measure your pulse and blood pressure.
This progression enables your doctor to compare the blood pressure readings from each area.
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After the test
After the test
The ankle-brachial index test is quick and usually takes just a few minutes. It’s a simple, non-invasive procedure that doesn’t require any drugs or sedatives. You will be able to drive yourself after the procedure and continue with your normal daily plans and routine.
Before the test
On the day of the test, the healthcare provider performing the test will review your medical history. You will lie on your back 10 to 30 minutes before the test.During the test
An ABI test measures your systolic blood pressure, a measurement of how much pressure blood places on your artery walls as your heart contracts.
During the test, your systolic blood pressure will be measured in both of your arms and your ankles.
Each time your blood pressure is taken, your provider will place a cuff around your arm or ankle. After inflating the cuff, they will place a small ultrasound device against your skin to measure your pulse and blood pressure.
This progression enables your doctor to compare the blood pressure readings from each area.
After the test
The ankle-brachial index test is quick and usually takes just a few minutes. It’s a simple, non-invasive procedure that doesn’t require any drugs or sedatives. You will be able to drive yourself after the procedure and continue with your normal daily plans and routine.Ankle-brachial index results
To determine your ABI value, your provider divides the pressure measurements in your ankles by the pressure measurements in your arms. The values will be sent to your referring provider, who will review the test results and recommend the appropriate next steps.
Based on the number from your ankle-brachial index (ABI) test, your results may show:
- No artery blockage (1.0 to 1.4): If your ABI is in this range, you probably don’t have peripheral artery disease (PAD). But if you still have symptoms, you might need another ABI test after exercising.
- Borderline blockage (0.90 to 1.0): You may have early signs of PAD. Your arteries might be starting to narrow, but blood flow isn’t blocked yet. Although the ABI is very accurate, you may get a normal reading even if you have symptoms of PAD. If that’s the case, your doctor may recommend other tests to confirm or rule out a diagnosis.
- PAD (less than 0.90): Results lower than 0.9 suggest PAD. The lower the number, the more severe the PAD. You might need more tests, like an ultrasound or angiography, to check the arteries in your legs.
- Calcification/vessel hardening (higher than 1.4): ABI values above 1.4 indicate a calcified vessel. This means you have plaque buildup in your arteries, causing them to harden.
What does a high ankle-brachial index mean?
An ankle-brachial index greater than 1.4 may suggest the presence of arterial calcification. Calcification in your arteries can occur as you age, but it’s also a sign of heart disease and can increase your risk of heart attacks. Working with a vascular specialist can help you find medications, lifestyle changes or other treatments to address plaque buildup and other conditions, such as diabetes, that can contribute to its formation.
Find a location near you
You can receive an ABI test at Baylor Scott & White locations throughout Central and North Texas. Your results will be shared with your provider, and we can help you arrange for additional care at one of our many heart and vascular locations.
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