What Is an Ankle-Brachial Index (ABI)?
An Ankle-Brachial Index (ABI) is a simple, noninvasive vascular examination used to evaluate blood flow to the legs and screen for Peripheral Arterial Disease (PAD). The examination compares the blood pressure measured at the ankles with the blood pressure measured in the arms to determine how well blood is circulating to the lower extremities.
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During the examination, blood pressure cuffs are placed on both arms and ankles, and a handheld Doppler device is used to measure arterial blood flow. The ankle pressure is then compared to the highest arm pressure to calculate the Ankle-Brachial Index (ABI), which helps identify narrowing or blockage in the arteries supplying the legs.
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The examination is painless, does not involve radiation, and typically takes 15–30 minutes to complete. An ABI is often the first test performed when evaluating leg pain with walking (claudication), poor circulation, nonhealing wounds, or other symptoms that may indicate peripheral arterial disease.
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By detecting circulation problems early, an ABI can help guide further vascular evaluation and treatment, often before more serious complications develop.
How It Works
Calculation Formula
ABI = Ankle BP ÷ Highest Arm BP
The ABI is a standard indicator of vascular health, helping to identify circulation efficienty from heart to extremities.
Why Is an Ankle-Brachial Index (ABI) Performed?
An Ankle-Brachial Index (ABI) is performed to evaluate circulation in the legs and identify reduced blood flow caused by narrowing or blockage of the arteries. It is one of the most effective noninvasive screening tests for Peripheral Arterial Disease (PAD) and can help detect vascular disease before symptoms become severe.
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An ABI is commonly recommended for individuals experiencing leg pain while walking (claudication), cramping, numbness, or nonhealing wounds of the feet or legs. It is also valuable for people with risk factors such as diabetes, smoking, high blood pressure, high cholesterol, or a family history of vascular disease.
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In addition to diagnosing peripheral arterial disease, an ABI helps assess the severity of arterial disease, monitor changes in circulation over time, and evaluate the success of vascular procedures such as angioplasty, stent placement, or bypass surgery.
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Because the examination is quick, painless, and does not use radiation, it serves as an excellent first-line test for evaluating lower extremity circulation and determining whether additional vascular testing or treatment may be beneficial.
Common Reasons to Schedule an Ankle-Brachial Index (ABI)
An Ankle-Brachial Index (ABI) measures the blood pressure in your ankles and compares it to the blood pressure in your arms to evaluate blood flow to your legs. This simple, noninvasive physiologic vascular test is one of the most effective ways to detect peripheral arterial disease (PAD) and assess the severity of reduced circulation. You may benefit from this examination if you have symptoms or medical conditions that suggest decreased blood flow to your legs.
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Leg pain while walking (claudication)
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Calf, thigh, or buttock pain that improves with rest
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Leg pain at rest
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Cold feet or toes
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Numbness or tingling related to poor circulation
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Weakness or fatigue in the legs during activity
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Slow-healing wounds or ulcers on the feet or legs
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Non-healing sores or gangrene of the toes or feet
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Suspected peripheral arterial disease (PAD)
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Diabetes with concern for reduced circulation
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High blood pressure, high cholesterol, or a history of smoking with symptoms of vascular disease
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Weak or absent pulses in the feet or ankles
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Evaluation before or after vascular surgery, angioplasty, or stent placement
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Monitoring previously diagnosed peripheral arterial disease
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Assessment of abnormal findings from a physical examination or another vascular study
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An Ankle-Brachial Index (ABI) is a safe, painless, noninvasive, and radiation-free examination that provides a quick and reliable assessment of blood flow to your legs. It helps detect peripheral arterial disease, determine the severity of reduced circulation, and guide appropriate diagnosis, treatment, and follow-up care.
What to Expect During Your Examination
An Ankle-Brachial Index (ABI) examination is a quick, comfortable, and noninvasive test that typically takes 15–30 minutes to complete. No needles, injections, or radiation are involved.
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During the examination, you will lie comfortably on an examination table while blood pressure cuffs are placed around both upper arms and both ankles. A handheld Doppler device is then used to detect blood flow within the arteries of your arms and ankles as each cuff is gently inflated and deflated to measure your blood pressure.
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The blood pressure measured at each ankle is compared with the highest blood pressure measured in your arms to calculate your Ankle-Brachial Index (ABI). This information helps evaluate circulation to your legs and determine whether there is evidence of peripheral arterial disease (PAD).
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The examination is painless, although you may briefly feel pressure as the cuffs inflate. Once the measurements are complete, the cuffs are removed, and you can immediately return to your normal daily activities without any restrictions.
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If additional physiologic testing, such as Toe-Brachial Index (TBI), Segmental Pressure Studies, Pulse Volume Recordings (PVR), or Exercise ABI Testing, is needed, these examinations may be recommended based on your symptoms or the results of your ABI evaluation.
How to Prepare for Your Ankle-Brachial Index (ABI) Examination
An Ankle-Brachial Index (ABI) Examination requires very little preparation. Following these simple instructions will help ensure your examination is completed comfortably and accurately.
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Before Your Appointment
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✓ No fasting is required. You may eat and drink normally before your examination.
✓ Continue taking your prescribed medications unless instructed otherwise by your healthcare provider.
✓ Avoid smoking, chewing tobacco, vaping, or using nicotine products for at least 2 hours before your appointment, as nicotine can temporarily reduce blood flow and affect the accuracy of the examination.
✓ Avoid caffeine for at least 2 hours before your examination, including coffee, tea, energy drinks, and caffeinated sodas, as caffeine may temporarily affect blood vessel function.
✓ Wear comfortable, loose-fitting clothing that allows easy access to your arms and legs. You will be asked to remove your shoes and socks before the examination.
✓ Keep your feet warm before your appointment whenever possible, especially during colder weather, as cold temperatures can temporarily reduce blood flow and influence the test results.
✓ Bring any previous vascular ultrasound, physiologic testing, CT angiography (CTA), MR angiography (MRA), or angiogram reports related to your leg circulation if they were performed at another facility.
✓ Arrive 10–15 minutes early to complete any necessary paperwork before your examination.
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An Ankle-Brachial Index (ABI) Examination is a safe, painless, noninvasive, and radiation-free test that does not require contrast dye or injections. During the examination, blood pressure cuffs are placed on your arms and ankles, and a handheld Doppler device is used to measure blood flow. These measurements are compared to assess circulation to your legs and help detect peripheral arterial disease (PAD). Following these instructions will help ensure the most accurate and reliable results.
Frequently Asked Questions
Q: What is an Ankle-Brachial Index (ABI)?
A: An ABI is a noninvasive vascular examination that compares the blood pressure in your ankles to the blood pressure in your arms. It is commonly used to screen for and evaluate Peripheral Arterial Disease (PAD).
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Q: Why might I need an ABI?
A: You may benefit from an ABI if you experience leg pain while walking, cold feet, numbness, slow-healing foot wounds, or have risk factors such as diabetes, smoking, high blood pressure, or high cholesterol.
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Q: Is the examination painful?
A: No. The examination is painless. You will feel temporary pressure as the blood pressure cuffs inflate, similar to having your blood pressure taken during a routine medical visit.
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Q: How long does the examination take?
A: Most ABI examinations take approximately 15–30 minutes to complete.
Q: Do I need to fast before my appointment?
A: No. Fasting is not required. However, you should avoid smoking, nicotine products, and strenuous exercise for at least two hours before your examination whenever possible.
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Q: Does the examination involve radiation?
A: No. An ABI uses blood pressure cuffs and a handheld Doppler device to measure blood flow. There is no radiation exposure.
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Q: What happens if my ABI is abnormal?
A: An abnormal ABI may indicate reduced blood flow to your legs. Depending on your results, additional examinations such as a Toe-Brachial Index (TBI), Segmental Pressure Study, Pulse Volume Recordings (PVR), Exercise ABI Testing, or a vascular ultrasound may be recommended.
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Q: Can I return to my normal activities afterward?
A: Yes. There are no restrictions following an ABI examination, and you may resume your normal daily activities immediately.
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Q: Can I schedule an ABI without a referral?
A: Yes. We welcome both healthcare provider referrals and self-pay patients seeking a vascular screening or circulation evaluation.
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Q: Will I receive my results the same day?
A: Your examination will be interpreted by an experienced vascular specialist. Results are typically provided promptly and shared with you and, if applicable, your referring healthcare provider.
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Q: Do I need a referral for an Ankle-Brachial Index (ABI) examination?
A: No. A referral is not required if you choose to schedule the examination as a self-pay patient. However, if you plan to use health insurance, a referral or physician's order may be required depending on your insurance plan. If you're unsure, our office will be happy to help determine your coverage and scheduling options.
Schedule Your Ankle-Brachial Index (ABI) Examination
Whether your examination has been recommended by your healthcare provider or you are scheduling a self-pay vascular screening, we're committed to providing a professional, comfortable, and convenient experience.
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Choose the option below to schedule your examination:
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Ankle-Brachial Index (ABI) Examination
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If you're unsure whether an Ankle-Brachial Index (ABI) is the most appropriate examination for your symptoms, or if you have a history of peripheral arterial disease, previous vascular surgery, stent placement, or bypass surgery, please contact our office before scheduling. We'll be happy to help determine whether this is the right examination for you.
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If you are experiencing sudden severe leg pain, a cold or pale foot, loss of sensation, inability to move your foot or toes, or rapidly worsening symptoms, seek immediate medical attention. An Ankle-Brachial Index (ABI) examination is intended for diagnostic evaluation and screening and is not a substitute for emergency medical care.
Why Choose Alpha Vascular?
Experienced Sonographer
Board-Certified Interpretation
Advanced Ultrasound Technology
