Of all the medical tests available for early disease detection, the ankle-brachial index may be the simplest, most affordable, and most underutilized. It takes 15 minutes, involves no needles or contrast dye, requires no preparation, causes zero discomfort — and it can detect peripheral artery disease years before symptoms become limb-threatening.
Yet millions of Americans who should be screened never are. The 2024 ACC/AHA PAD Guideline identifies this screening gap as a major contributor to late-stage diagnosis and preventable amputations.
This article explains exactly what the ABI test is, how it works, what the results mean, and who should get one.
How the ABI Test Works
The ankle-brachial index is a ratio — a comparison of blood pressure in your ankle to blood pressure in your arm.
The procedure is straightforward. You lie flat on an exam table. A technician places standard blood pressure cuffs on both arms and both ankles. Using a handheld Doppler ultrasound device (a small probe that detects blood flow sounds), the technician measures systolic blood pressure at each location. The highest ankle pressure is divided by the highest arm pressure to produce the ABI ratio.
A healthy cardiovascular system delivers equal blood pressure to the arms and ankles, producing a ratio close to 1.0. When PAD narrows the leg arteries, blood pressure drops at the ankle — the same way water pressure drops downstream from a kink in a garden hose — producing a ratio below 1.0.
The test takes approximately 15 minutes. It requires no fasting, no preparation, no contrast dye, and no sedation. It can be performed in any vascular office, including all SACMD locations.
Understanding Your Results
| ABI Value | Interpretation | What It Means |
|---|---|---|
| 1.00–1.40 | Normal | No evidence of significant arterial narrowing |
| 0.91–0.99 | Borderline | May indicate early disease; clinical correlation needed |
| 0.71–0.90 | Mild PAD | Some arterial narrowing present; medical therapy recommended |
| 0.41–0.70 | Moderate PAD | Significant arterial disease; may need intervention |
| ≤0.40 | Severe PAD | Critical reduction in blood flow; urgent evaluation needed |
| >1.40 | Non-compressible | Calcified arteries (common in diabetes); alternative testing needed |
What a low ABI tells you beyond your legs. A low ABI doesn’t just diagnose PAD — it identifies you as someone at elevated cardiovascular risk. Even mildly abnormal ABI values (0.91–0.99) are associated with increased risk of heart attack and stroke. This is because the atherosclerosis detected in your leg arteries is almost certainly present in your coronary and carotid arteries as well.
The ABI in Diabetic Patients: An Important Caveat
For diabetic patients, the ABI has a significant limitation. Diabetes accelerates medial arterial calcification — calcium deposits that stiffen the artery walls and make them resistant to compression by the blood pressure cuff. This produces falsely elevated ABI readings, potentially masking significant PAD.
When the ABI is above 1.40 — or when clinical suspicion for PAD is high despite a normal ABI in a diabetic patient — additional tests are needed. Toe-brachial index (TBI) measures pressure in the toe arteries, which are less susceptible to calcification. A TBI below 0.70 suggests PAD. Pulse volume recordings (PVR) measure blood volume changes in the legs at multiple levels, providing functional assessment unaffected by calcification. Duplex ultrasound directly visualizes blood flow through the arteries and can identify areas of narrowing.
Who Should Get an ABI Test?
The 2024 ACC/AHA guideline recommends ABI screening for all adults age 65 and over regardless of symptoms, adults age 50 and over with any atherosclerotic risk factor (diabetes, smoking history, hypertension, hyperlipidemia, chronic kidney disease, family history of cardiovascular disease), any adult with leg symptoms suggestive of PAD (claudication, leg fatigue with walking, non-healing foot wounds), and adults of any age with known atherosclerotic disease in another vascular bed (coronary artery disease, carotid artery disease).
Women are screened at lower rates than men despite equal PAD prevalence — a disparity the guideline explicitly calls out.
Frequently Asked Questions
ABI Testing at SACMD
At Surgical Associates, ABI and comprehensive vascular diagnostic testing are available at all five locations: Camp Springs, Waldorf, Silver Spring (Maryland), Washington DC, and Reston (Virginia). No referral is required. The test is covered by Medicare and virtually all commercial insurance plans when performed for a clinical indication.
If your ABI reveals PAD, the next step is a comprehensive treatment plan — including medical therapy optimization, structured exercise, and evaluation for potential revascularization if symptoms warrant it.
What to ask your doctor: ‘Given my age and risk factors, should I have an ABI test? If the result is borderline or abnormal, what’s the next step?’
Schedule a consultation: Call (240) 427-1630 or visit www.sacmd.com
Disclaimer: This article is for informational purposes only and does not constitute medical advice.
References: -e 1. Gornik HL, et al. 2024 ACC/AHA PAD Guideline. JACC. 2024;83(24):2497-2604. 2. Aboyans V, et al. ABI — Interpretation and Clinical Significance. Eur Heart J. 2018. 3. Mayo Clinic. Ankle-Brachial Index Test. mayoclinic.org. 4. Cleveland Clinic. ABI Test — What to Expect. 5. Das SR, et al. PAD in Diabetes ACC Scientific Statement. JACC. 2025.
