The ankle-brachial index (ABI) 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.
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.
In the emergency or trauma setting, an ABI is useful for the evaluation of a patient who is at increased risk for lower-extremity arterial injury as follows:
• An ABI less than 0.90 suggests a need for further vascular imaging: angiography in a stable patient, and operative exploration in an unstable patient
• An ABI greater than 0.90 decreases the likelihood of an arterial injury; thus, the patient may be observed with serial ABI assessments or may undergo a vascular study on a delayed basis