Ankle Brachial Index (ABI): Test Procedure, Results and Benefits

Lab Test and Medical Investigation

What is an Ankle-Brachial Index Test?

An ankle-brachial index test (ABI) is a simple yet effective non-invasive test to check for Peripheral Artery Disease (PAD). Peripheral Artery Disease reduces the blood flow in arms and legs due to blocked arteries, which increases the risk of heart stroke and attack. An ankle-brachial test compares the blood pressure measured at both ankle and arm immediately after walking on a treadmill. A low ankle-brachial index score probably means that you have poor blood flow in your legs.

Test Procedure:

Who should get this procedure?

This test procedure is conducted to check if you have any blocked arteries in your legs or arms. It is also conducted if

You have a history of tobacco consumption.
You have diabetes and you are 50 or above.
You have high cholesterol
You have high blood pressure.
You have high levels of lipids in your blood or are above 70 years with high blood pressure.
You are prone to coronary artery disease.
You exhibit symptoms of PAD

Before the Test:

Do not take a heavy meal an hour before the test.
Do not exercise one hour before the test.
Do not eat or drink food items that contain caffeinated substances one day before the test.
Do not consume alcohol or food items that contain alcohol one day before the test.
Avoid tight-fitting clothes and wear comfortable, loose-fitting ones.

During the Test:

The test usually takes about 10 to 15 minutes and includes the following steps:

The doctor asks you to lie down on the table.
He/she checks your blood pressure level by wrapping a cuff around your arm.
He/she applies a gel just below the cuff on your arm.
The doctor attempts to hear your blood pressure flow with a Doppler Ultrasound device.
This device helps the doctor decide when to note your blood pressure readings.
Your doctor will repeat the same process for both your arms and ankles.

If you have leg pain, your doctor may probably want to check you for PAD. To make sure it’s PAD, your doctor needs two ankle-brachial index test readings for which the test is done twice, one before the treadmill exercise and one after the exercise.

It is a non-invasive procedure. Hence, you don’t feel any pain. However, you feel a little discomfort when the cuff inflates, but it stops as soon as the doctor unwraps the cuff from your arm.

After the Test:

An ankle-brachial test is a simple and quick procedure and takes only 10 to 15 minutes. You don’t have to follow any precautions after the test. Your doctor will let you know the test results within a few minutes after the test.
Make sure you follow up with your doctor to know your test results and get more information regarding your health condition.

Results:

Your doctor uses your blood pressure measurements to calculate your ankle-brachial index. Based on the index score, you may have any of the following listed below:

1.0 – 1.4: A score of 1.0 to 1.4 means you have no blockage. However, if you still show PAD symptoms, your doctor will advise you to exercise and take the ankle-brachial test.
0.91-0.99: A score of 0.91 to 0.99 suggests that you probably have borderline PAD. In this case, your doctor might suggest the exercise ankle-brachial test.
Less than 0.90: A score of less than 0.90 is indicative of an abnormal condition, and your doctor might advise additional tests, including ultrasound or angiography, to assess the condition of arteries in your legs.

If you have diabetes or significantly blocked arteries, your doctor might call for a Toe Brachial Index. Toe brachial index is the measurement of blood pressure at your toes. Your doctor might recommend this test for more accurate results if you have diabetes and have significantly blocked arteries.

Why is this Procedure Conducted?

This procedure is conducted to check if you have PAD, reduced blood flow, or blocked arteries in your legs or arms.

Risks Associated:

An ankle-brachial test is a simple test and doesn’t have any risks associated with it as it involves measuring only your blood pressure. However, you might feel slight discomfort when the doctor measures your arm’s blood pressure as your doctor inflates the cuff. But it will be only for a minute. Once your doctor removes the cuff, the discomfort reduces automatically.

If you exhibit severe PAD symptoms, your doctor will suggest other tests to get more accurate results and evaluate whether you have PAD.

When to Consult a Doctor?

If you observe any or all the following symptoms, you need to consult your doctor:

Less hair on your legs than usual.
Pale skin.
If one leg feels colder.
Toenails are growing slower than they usually grow.
Skin looking bluish.

If you notice these symptoms, it is recommended that you consult your doctor as soon as possible.

Benefits:

The ankle-brachial index is a most reliable test that provides accurate results.
It is quicker than other tests and done within 10 to 15 minutes.
This test is non-invasive. It means the medical examination doesn’t require cutting through the skin or entering any body parts.
An ankle-brachial test is a simple test as it only measures and compares blood pressure of the arm and ankle.

Conclusion:

After carefully examining your test results and going through your medical history and symptoms, your doctor will explain the next step, if any. Otherwise, he/she will advise you to make lifestyle changes or put you on medications. The doctor may advise you to consult a vascular specialist specializing in arteries and veins if your condition is severe.

Frequently Asked Questions (FAQs):

Are there any complications post the ankle-brachial test?

Besides feeling a little discomfort during the test, there will be no complications during or after the test.

At what ratio is ABI considered normal?

A 1.4 ABI score is considered normal.

Do I have to follow any specific diet before the test?

You can carry on with your regular diet. However, make sure that your diet doesn’t include alcohol, caffeinated items, or fast food, and avoid heavy meals before the test.