Introduction: Who Should Undergo Diagnostics and When

Not everyone with peripheral artery disease experiences obvious symptoms, which makes knowing when to seek diagnostic testing particularly important. Many people with this condition have no symptoms at all, especially in the early stages, while others develop leg pain or discomfort that they mistakenly attribute to normal aging.^[1]

You should consider seeking diagnostics if you experience recurring leg pain when exercising or walking that goes away with rest. This type of pain is called claudication, which means “to limp,” and it happens when your leg muscles don’t get enough oxygen-rich blood during activity. The pain typically appears in the calves, thighs, or buttocks and stops within about ten minutes of resting.^[2]

Other signs that warrant diagnostic evaluation include coldness in your lower leg or foot, changes in skin color (such as pale or bluish skin), wounds or sores on your feet or legs that heal slowly or not at all, and numbness or weakness in your legs. You might also notice hair loss on your legs and feet, shiny skin, or slow-growing toenails. These changes happen because poor circulation affects how tissues receive nutrients and oxygen.^[1]

Certain individuals should undergo diagnostics even without symptoms. If you are over 50 years old and have risk factors such as smoking, diabetes, high blood pressure, high cholesterol, or a family history of heart disease, your doctor may recommend screening. People over 60 years old are at particularly high risk, as the prevalence of PAD increases dramatically with age, affecting nearly 20% of people in this age group.^[3]

Smoking is the single most important risk factor for peripheral artery disease, increasing the risk fourfold. If you smoke or have smoked in the past, discussing diagnostic testing with your healthcare provider makes sense. Similarly, if you have diabetes, chronic kidney disease requiring dialysis, or a history of stroke or coronary artery disease, you face higher odds of having PAD even without leg symptoms.^[4]

Black individuals face a higher risk of developing PAD compared to white individuals, particularly after age 50 for males and age 60 for females. Hispanic people may also have similar or slightly higher rates compared to non-Hispanic white people. If you belong to these groups and have additional risk factors, proactive screening discussions with your doctor are worthwhile.^[2]

Classic Diagnostic Methods Used to Identify the Disease

The diagnostic journey for peripheral artery disease typically begins with a physical examination by your healthcare provider. During this exam, your doctor will ask about your symptoms, medical history, and risk factors. They will carefully check for physical signs that might indicate reduced blood flow to your legs.^[10]

One of the most revealing parts of the physical exam involves checking the pulses in your feet and legs. Your doctor will feel for pulses in various locations, including behind your knee and on the top of your foot. When PAD is present, these pulses may feel weak or might be absent altogether. The doctor will also listen with a stethoscope over your arteries, particularly the femoral artery in your groin area. A whooshing sound, called an arterial bruit, can indicate turbulent blood flow through a narrowed artery.^[7]

Your doctor will examine your skin closely, looking for specific changes that suggest poor circulation. The skin on your legs might appear shiny and tight, or it might have lost hair. Your legs might feel cool to the touch compared to other parts of your body, or one leg might feel noticeably cooler than the other. These temperature differences occur because less warm blood is reaching the affected areas.^[7]

When PAD becomes more severe, additional physical signs become apparent. These include muscle wasting in the calf, thick and slow-growing toenails, pale skin that might take on a blue color (called cyanosis), and painful sores on the feet or toes that don’t heal properly. The presence of these signs indicates more advanced disease that requires prompt attention.^[7]

Ankle-Brachial Index (ABI)

The ankle-brachial index, or ABI, is the most common and important test used to diagnose peripheral artery disease. This test is noninvasive, meaning it doesn’t require needles or incisions, and it’s quite simple to perform. The ABI compares the blood pressure in your ankle with the blood pressure in your arm to determine how well blood is flowing to your legs.^[3]

During an ABI test, you’ll lie flat on an examination table while a healthcare provider measures your blood pressure in both arms using a regular blood pressure cuff. Then they’ll measure the blood pressure at your ankles. The ankle pressure should normally be the same as or slightly higher than the arm pressure. However, if your leg arteries are narrowed by plaque buildup, the blood pressure in your ankles will be lower than in your arms because less blood is getting through.^[10]

The ABI result is expressed as a number. A normal ABI is 1.0 to 1.4, meaning the ankle pressure equals or slightly exceeds the arm pressure. An ABI between 0.9 and 0.99 suggests early PAD, while an ABI of 0.8 to 0.9 indicates mild disease. Values between 0.5 and 0.8 represent moderate disease, and an ABI below 0.5 signals severe PAD that requires immediate attention.^[9]

Sometimes, doctors perform an exercise ABI test. This involves measuring your ABI both before and immediately after you walk on a treadmill or exercise. Some people with PAD have normal resting blood pressures but experience symptoms when active. The exercise ABI can reveal problems that don’t show up during a resting test. After exercise, if you have PAD, the blood pressure in your ankles may drop noticeably, confirming the diagnosis even when the resting ABI appeared normal.^[10]

Blood Tests

Blood tests play an important supporting role in diagnosing and managing peripheral artery disease. While they don’t directly detect narrowed arteries, they help identify conditions that increase your risk of PAD or may have caused it. Your doctor will likely order blood tests to check your cholesterol levels, blood sugar levels (to screen for diabetes), and kidney function.^[10]

High cholesterol, particularly elevated levels of LDL or “bad” cholesterol, contributes to the formation of fatty deposits in artery walls. A blood test showing high cholesterol helps explain why PAD developed and guides treatment decisions. Similarly, testing for diabetes is crucial because poorly controlled blood sugar significantly worsens PAD symptoms and accelerates disease progression.^[7]

Ultrasound Examination

Ultrasound is a safe, painless imaging technique that uses sound waves to create pictures of blood flowing through your vessels. A special type called Doppler ultrasound is particularly useful for evaluating peripheral artery disease. During this test, a technician moves a handheld device called a transducer over the skin of your legs, focusing on areas where major arteries run.^[10]

Doppler ultrasound can show where arteries have become narrowed or blocked and can measure how fast blood is flowing through different parts of your leg arteries. This information helps doctors pinpoint exactly where the problem areas are located and how severe the narrowing has become. The test takes about 30 to 60 minutes and doesn’t involve any radiation exposure.^[10]

Advanced Imaging Tests

When more detailed information is needed, your doctor may order advanced imaging studies. Computed tomography angiography (CTA) uses X-rays and a contrast dye injected into your veins to create detailed pictures of your arteries. The dye makes your blood vessels show up clearly on the images, allowing doctors to see exactly where blockages or narrowing exist.^[10]

Magnetic resonance angiography (MRA) works similarly to CTA but uses magnetic fields and radio waves instead of X-rays. It also requires a contrast dye to highlight blood vessels. Both CTA and MRA provide three-dimensional images that show the anatomy of your arteries in great detail, helping doctors plan treatment if procedures or surgery become necessary.^[10]

Angiography is the most detailed imaging test for PAD. During this procedure, a doctor inserts a thin tube called a catheter into an artery, usually in your groin. They then inject contrast dye directly into your arteries while taking X-ray images. Angiography provides the clearest, most precise pictures of arterial blockages. However, because it’s invasive and carries slightly higher risks than other tests, it’s typically reserved for cases where doctors are planning to perform a procedure to open blocked arteries during the same session.^[10]

Diagnostics for Clinical Trial Qualification

When patients with peripheral artery disease consider participating in clinical trials, they must undergo specific diagnostic tests to determine whether they qualify for the study. These tests serve two purposes: they confirm the diagnosis of PAD and measure how severe the disease is, and they ensure that participants meet the specific criteria the researchers have established for the trial.

The ankle-brachial index remains the cornerstone test for qualifying patients for PAD clinical trials. Most trials require participants to have a documented ABI measurement that falls within a specific range, typically between 0.4 and 0.9, which indicates moderate to severe disease. This ensures that the trial enrolls patients who are sick enough to potentially benefit from the experimental treatment but not so severely ill that they require emergency interventions.^[14]

Clinical trials often require exercise ABI testing as part of the qualification process. This test helps researchers understand how the disease affects patients during activity, which is when symptoms typically appear. Participants may need to demonstrate a specific decrease in ankle pressure after walking on a treadmill, proving that physical activity triggers reduced blood flow to their legs.

Imaging studies such as ultrasound, CTA, or MRA are commonly required for trial participation. These tests help researchers document the exact location and extent of arterial narrowing in each participant. Knowing the precise anatomy of the disease allows researchers to better interpret how patients respond to treatment and whether improvements occur in the targeted areas.

Blood tests form another essential component of clinical trial qualification. Researchers typically check cholesterol levels, blood sugar (to identify diabetes), kidney function, liver function, and blood cell counts. These baseline measurements help ensure patient safety during the trial and allow researchers to monitor for any side effects the experimental treatment might cause. Patients with severely abnormal blood test results might be excluded from trials if those abnormalities could interfere with the treatment or put the patient at unacceptable risk.

Some trials focus on testing new procedures or devices to open blocked arteries. For these studies, angiography is usually required before enrollment. The detailed images from angiography show researchers exactly which arteries are blocked and whether the blockages are suitable for the specific procedure being studied. Not all blockages can be treated with every type of procedure, so this imaging confirms that participants have the right type of disease for the intervention being tested.

Questionnaires about walking ability and quality of life are standard diagnostic tools for PAD clinical trials. Researchers ask participants to complete detailed surveys about how far they can walk before leg pain begins, how the disease affects their daily activities, and how their symptoms impact their overall well-being. These patient-reported outcomes help researchers measure whether a new treatment improves not just blood flow numbers, but actual symptoms and quality of life.

Walking tests on a treadmill provide objective measurements of functional ability. During these tests, participants walk at a set speed and incline while researchers measure how far they can go before leg pain forces them to stop. This information establishes a baseline that researchers can compare to measurements taken during and after treatment to determine whether the intervention improved walking ability.