PAD screening is a simple, noninvasive test that checks for peripheral artery disease, a condition where narrowed arteries reduce blood flow to the legs. The primary screening tool is the ankle-brachial index (ABI), a painless comparison of blood pressure readings taken at your arm and ankle. The test takes about 10 to 15 minutes and can detect poor circulation before serious complications develop.
How the ABI Test Works
The ankle-brachial index measures whether blood is flowing to your legs as strongly as it flows to your arms. You lie flat on an exam table while a clinician wraps a standard blood pressure cuff around your upper arm and inflates it. Instead of using a stethoscope, they place a small handheld Doppler ultrasound device over the artery at your inner elbow to listen for the pulse. When the cuff deflates and the pulse sound returns, that pressure reading is your arm’s systolic blood pressure.
The same process is repeated at each ankle. The cuff goes just above the ankle bone, and the Doppler probe picks up pulse signals from two arteries in the foot: one on the top of the foot and one behind the inner ankle bone. The clinician records whichever reading is higher for each leg.
Your ABI score is calculated by dividing the higher ankle pressure by the higher arm pressure. A perfectly healthy result means blood pressure at your ankle is roughly the same as in your arm, producing a ratio near 1.0. If the arteries in your legs are narrowed by plaque buildup, pressure at the ankle drops, and the ratio falls below 1.0.
What Your Score Means
ABI results fall into clear ranges that tell you and your doctor how well blood is reaching your legs:
- 1.00 to 1.40: Normal blood flow
- 0.91 to 0.99: Borderline, warranting closer monitoring
- 0.41 to 0.90: Mild to moderate PAD
- 0.00 to 0.40: Severe PAD
- Above 1.40: Arteries are too stiff to compress properly, making the reading unreliable
That last category is particularly important for people with diabetes. Diabetes can cause calcium deposits in artery walls, making them rigid. When arteries can’t be compressed by the cuff, the ABI reading comes back falsely high, masking real blockages underneath. In these cases, a toe-brachial index (TBI) is used instead. The small arteries in the toes are rarely affected by this kind of calcification, so pressure measured at the big toe gives a more accurate picture. A TBI below 0.6 raises concern for PAD even when the standard ABI looks normal.
Who Should Be Screened
Major cardiology and vascular organizations agree on who benefits most from PAD screening, even without symptoms. The American Heart Association and American College of Cardiology recommend screening for:
- Anyone 65 or older
- Adults 50 to 64 with risk factors like diabetes, smoking history, high cholesterol, or high blood pressure
- Adults under 50 who have diabetes plus at least one additional risk factor
- Anyone already diagnosed with artery disease elsewhere in the body, such as coronary artery disease or an abdominal aortic aneurysm
European guidelines cast a slightly wider net, including people over 50 with a family history of atherosclerosis and those with chronic kidney disease or heart failure. The U.S. Preventive Services Task Force currently rates the evidence for screening the general asymptomatic population as “insufficient,” meaning it doesn’t recommend for or against universal screening. This doesn’t mean the test is unreliable. It reflects a gap in large-scale studies proving that screening people without any symptoms leads to better long-term outcomes across the board. For people with known risk factors, screening is widely recommended.
Physical Signs That Prompt Screening
Sometimes a doctor will order PAD screening based on what they see or what you describe during a visit. The CDC lists several physical signs that suggest reduced blood flow to the legs: weak or absent pulses in the feet, hair loss on the legs, smooth or shiny skin, skin that feels cool to the touch, muscle weakness or wasting, and sores or ulcers on the legs or feet that heal slowly or not at all. Cold or numb toes are another red flag.
The hallmark symptom of PAD is called claudication: cramping or aching in the calves, thighs, or hips that starts when you walk and stops when you rest. If you notice this pattern, that alone is reason to ask about screening. Many people with PAD, however, have no symptoms at all, which is why risk-factor-based screening matters.
Why Early Detection Matters
PAD is not just a leg problem. Narrowed arteries in the legs signal that plaque buildup is likely happening in arteries throughout the body, raising the risk of heart attack and stroke. Catching it early creates a window to start treatment, typically through exercise programs, cholesterol-lowering medications, blood pressure management, and smoking cessation, before the disease progresses.
For people who already have wounds or ulcers on their legs, the timing of the ABI test appears to make a real difference. A study published in the Annals of Vascular Surgery found that among patients with lower-extremity ulcers, only 8% of those who received an ABI test within 30 days of their wound being identified required an amputation. Among those tested later, the amputation rate was 30%. While the difference didn’t reach full statistical significance due to the small study size, the pattern was striking enough that the researchers argued ABI timing should be a standard metric in wound care.
What Happens After an Abnormal Result
An abnormal ABI doesn’t mean you’ll need surgery. It does mean your doctor will want a clearer picture of where and how severe the blockages are. The next step is usually a duplex ultrasound, which combines standard ultrasound imaging with Doppler technology to show both the structure of your arteries and the speed of blood flowing through them. It’s painless and doesn’t involve radiation or needles.
If more detail is needed, particularly before planning a procedure, contrast-enhanced magnetic resonance angiography (MRA) offers the highest diagnostic accuracy. Studies show it detects blockages greater than 50% with sensitivity between 92% and 99.5%. CT angiography is another option, though MRA is generally preferred when available. These imaging tests map exactly where the narrowing is, how long the affected segment is, and how much blood flow remains, all of which determine whether treatment involves lifestyle changes, medication, or a procedure to restore flow.
Preparation and Cost
The ABI test itself requires almost no preparation. You’ll be asked to lie down and rest for a few minutes before the measurements begin so your blood pressure stabilizes. There are no dietary restrictions for the ABI specifically, though if your doctor orders blood work like a cholesterol panel at the same visit, you may need to fast beforehand. Wear loose-fitting pants or shorts so the cuffs can be placed easily.
Coverage varies. Medicare does not cover the ABI as a standalone screening test for asymptomatic patients. If your doctor orders the test because you have symptoms, abnormal pulses, or a documented clinical concern, it is typically covered as a diagnostic test rather than a screening. Private insurance coverage depends on your plan and the reason for the test. If you’re paying out of pocket, an ABI performed in a primary care office with a handheld Doppler is one of the least expensive vascular tests available, often comparable to a standard office visit copay.