Ankle-Brachial Index Test

When might an ABI test be recommended?

A doctor or other qualified health professional may recommend an ABI test if you have symptoms or signs that could suggest PAD, such as leg pain during walking or exercise. Screening with a resting ABI may also be considered for people at increased risk of PAD, including:

• People aged 65 years or older
• People aged 50 to 64 years with risk factors for atherosclerosis, such as diabetes, a history of smoking, dyslipidaemia, hypertension, chronic kidney disease, or a family history of pad
• People aged under 50 years with diabetes and at least one additional risk factor for atherosclerosis
• People with known atherosclerotic disease in another vascular bed.

How do I prepare for an ABI test?

Preparation instructions may vary between clinics, so follow the advice given by your health professional or testing centre. In general:

• Don’t eat or drink anything that contains caffeine on the day of your test.
• Don’t exercise during the hour before your test, rest well before the test if advised.
• Just before the test, go to the restroom and pee until your bladder is empty.
• Wear loose, comfortable clothing so your provider can easily access your upper arms and ankles.

Tell your health professional if you have open wounds, leg ulcers, recent vascular surgery, or previous procedures to improve blood flow in your legs.

Some services may also ask you to avoid caffeine, smoking, alcohol or exercise for a period before the test.

What happens during the test?

You will usually lie flat on your back and rest briefly before the test. A blood pressure cuff is placed on each arm and ankle, and a handheld Doppler ultrasound device is used to detect blood flow in the artery. Blood pressure is measured in both arms and both ankles.

To perform an ABI test, your provider will:

1. Check the blood pressure in one of your arms
2. Check the blood pressure in the ankle that’s on the same side as the arm they just measured
3. Check the blood pressure in your other ankle
4. Check the blood pressure in your other arm

These measurements are then used to calculate the ABI. The test is usually quick and does not involve needles or sedation. Some people notice temporary pressure or mild discomfort while the cuffs inflate.

What happens after the test?

You can usually return to your normal activities straight after the test. A doctor or other qualified health professional will interpret the results and explain whether further assessment is needed. If the ABI result is abnormal, borderline, or non-compressible, additional vascular testing may be recommended.