Introduction: Who Should Undergo Diagnostics

If you experience leg pain when walking that goes away with rest, you might be dealing with more than just tired muscles. This pattern of discomfort could signal peripheral artery disease (also called PAD), a condition where your arteries become narrowed due to plaque buildup. The same condition can lead to blood clots forming in these narrowed vessels, causing what doctors call peripheral artery thrombosis.^[1]

You should consider seeking diagnostic testing if you notice certain warning signs. The most common symptom is a cramping pain in your legs, particularly in the calves or thighs, that starts when you’re active and stops when you rest. This pain occurs because your narrowed arteries can’t deliver enough blood to your leg muscles when they need it most during physical activity.^[2]

Other signs that suggest you need evaluation include coldness in your lower leg or foot compared to the other side, changes in skin color on your legs (such as pale, bluish, or shiny appearance), sores on your feet or toes that won’t heal, or numbness and weakness in your legs. Some people notice that hair grows more slowly on their legs and feet, or that their toenails grow unusually slowly.^[4]

Certain people face higher risks and should discuss screening with their doctor even if they don’t have symptoms yet. This includes anyone over age 65, people who have ever smoked regularly, those with diabetes, high blood pressure, or high cholesterol, and individuals with a family history of heart and blood vessel problems. If you’re younger than 65 but smoke or have diabetes, you should also consider evaluation if you have any leg symptoms.^[4]

Interestingly, many people with peripheral artery disease don’t experience any symptoms at all, especially in the early stages. Studies show that only about 10 percent of people with PAD experience the classic leg pain with walking. About half have various leg symptoms that differ from the typical pattern, and the remaining 40 percent have no leg symptoms whatsoever. This is why screening based on risk factors becomes so important for early detection.^[2]

Classic Diagnostic Methods

When you visit your doctor with concerns about possible peripheral artery problems, the evaluation typically begins with a conversation about your symptoms and medical history. Your doctor will ask detailed questions about any leg pain or discomfort you experience, when it happens, what makes it better or worse, and how long you’ve been noticing these issues.^[8]

The physical examination comes next. Your doctor will carefully check the pulses in your legs and feet by feeling for them with their fingertips. When arteries are narrowed or blocked, the pulse below that blockage becomes weak or may disappear entirely. They’ll also listen to your arteries using a stethoscope (a medical device for listening to sounds inside the body), particularly over the femoral arteries in your groin area, checking for unusual sounds called bruits (pronounced “brew-ee”), which are whooshing noises that suggest turbulent blood flow through narrowed vessels.^[4]

Your doctor will examine the skin on your legs and feet, looking for color changes, temperature differences, or wounds that aren’t healing properly. They may also check for hair loss on your legs and slow-growing toenails, both of which can indicate poor blood circulation over time.^[1]

Ankle-Brachial Index Test

The most common and straightforward test for diagnosing peripheral artery disease is the ankle-brachial index, often shortened to ABI. This test compares the blood pressure in your ankle with the blood pressure in your arm. The process is simple and doesn’t hurt. A healthcare provider will wrap blood pressure cuffs around your arms and ankles, then use a special ultrasound device to measure the blood pressure in both locations.^[8]

The ABI test works on a simple principle: normally, the blood pressure in your ankle should be about the same as or slightly higher than the blood pressure in your arm. When arteries in your legs are narrowed, the blood pressure in your ankles drops compared to your arms. The test gives a number that represents the ratio between these pressures. An ABI result below a certain threshold suggests that your leg arteries are narrowed.^[12]

Sometimes, if your resting ABI test comes back normal but you still have symptoms when you walk or exercise, your doctor may recommend an exercise ABI test. For this version, your blood pressures are measured before and immediately after you walk on a treadmill. This helps identify problems that only show up when your muscles need more blood during activity.^[8]

Current medical guidelines recommend ABI testing for people whose medical history or physical examination suggests they might have peripheral artery disease. However, screening everyone without symptoms or risk factors isn’t recommended, as the condition is uncommon in younger, healthy people without risk factors.^[12]

Ultrasound Examination

Ultrasound testing uses sound waves to create pictures of how blood moves through your blood vessels. A special type called Doppler ultrasound can detect blocked or narrowed arteries in your legs. During this test, a technician applies gel to your skin and moves a small device called a transducer over your legs. The sound waves bounce off your blood cells and create images that show whether blood is flowing normally or if there are blockages.^[8]

This test is completely painless and doesn’t use radiation. It can provide detailed information about where narrowings or blockages are located and how severe they are. The test can also help distinguish between different causes of reduced blood flow.^[2]

Blood Tests

Your doctor will likely order blood tests to check for conditions that increase your risk of peripheral artery problems or that might be causing your symptoms. These tests typically measure your cholesterol levels, including the “bad” LDL cholesterol that contributes to plaque buildup in arteries. They’ll also check your blood sugar levels to screen for diabetes or see how well-controlled your diabetes is if you already have it.^[8]

Blood tests help your doctor understand the underlying causes contributing to your artery problems and guide treatment decisions. They also help rule out other conditions that might cause similar symptoms.^[2]

Advanced Imaging Tests

When more detailed pictures of your arteries are needed, your doctor might order specialized imaging tests. Angiography is a test that uses X-rays combined with a special dye to create detailed images of your arteries. The dye is injected through a thin tube inserted into a blood vessel, usually in your groin or arm. As the dye travels through your arteries, X-ray pictures are taken that clearly show any blockages or narrow spots.^[8]

Other imaging options include computed tomography angiography (CTA) and magnetic resonance angiography (MRA). Both create detailed three-dimensional images of your blood vessels. CTA uses X-rays and computer technology, while MRA uses powerful magnets and radio waves. These tests can show the exact location and severity of blockages without requiring a catheter to be inserted into your arteries, though they still typically require injection of a contrast material to make the blood vessels visible.^[5]

Diagnostics for Clinical Trial Qualification

When researchers conduct clinical trials to test new treatments for peripheral artery disease and thrombosis, they need to ensure that participants truly have the condition they’re studying. This requires standardized diagnostic criteria that can be applied consistently across all participants.

The ankle-brachial index remains a cornerstone test for determining eligibility for many clinical trials studying peripheral artery disease. Researchers typically use specific ABI cutoff values to define who has PAD and at what severity level. This allows them to enroll patients with similar degrees of disease and to measure whether a treatment improves blood flow after the trial.^[12]

For studies specifically examining treatments for thrombosis (blood clots) in peripheral arteries, imaging tests play a crucial role in qualification. Researchers need to document exactly where clots are located, how large they are, and whether they’re causing complete or partial blockage of the artery. Ultrasound or angiography findings are often required to confirm that a participant has an actual clot rather than just narrowing from plaque buildup alone.^[9]

Clinical trials may also require specific symptom patterns for enrollment. For example, a study testing treatments for pain during walking would need participants who experience claudication (leg pain that occurs with activity and improves with rest) at a certain distance or after a certain amount of time. Researchers might use treadmill tests where participants walk at a set speed and doctors measure exactly how far they can walk before pain forces them to stop.^[12]

Blood tests are frequently part of clinical trial screening to ensure participants don’t have other conditions that might interfere with the study results or make the experimental treatment unsafe for them. These might include tests of kidney function, liver function, blood clotting ability, and markers of inflammation or other diseases.^[8]

Some clinical trials studying new treatments for peripheral artery thrombosis specifically enroll patients with acute (sudden) blockages rather than chronic (long-term) narrowing. These trials require documentation through imaging that the blockage is recent, typically within hours or days. This might involve comparing new imaging tests to older ones if available, or looking at characteristics of the clot that suggest it formed recently rather than having been present for a long time.^[14]

For trials testing thrombolytic therapy (treatments that dissolve blood clots), researchers need to carefully document the exact location and extent of clotting through angiography or other detailed imaging before enrolling participants. This helps them determine whether a participant is likely to benefit from the treatment being studied and allows them to measure how well the clot dissolves after treatment.^[14]