Peripheral Artery Disease - Diagnosis - Diagnosis

Your doctor will diagnose PAD based on your medical and family history, a physical exam, and the results from tests and procedures.

Medical history and physical exam

To help diagnose PAD, your doctor will want to learn about your signs and symptoms, risk factors, personal health history, and family health history. This discussion may include questions about the following:

  • Other medical conditions, including diabetes, heart disease, and chronic kidney disease
  • Pain or cramps in your legs while walking or exercising
  • Problems with your legs and feet, including swelling, redness, trouble with walking, and wounds that are slow to heal
  • Smoking, either currently or in the past
  • Your family history of PAD, heart disease, and other blood vessel diseases

During an exam to look for signs of PAD, your doctor will take these steps:

  • Check for weak pulses in your legs.
  • Listen for poor blood flow in your legs. Your doctor will use a stethoscope to listen for an abnormal whooshing sound, called a bruit.
  • Look for problems on your legs and feet, including swelling, sores, or pale skin.

Conditions that can seem like PAD

Some conditions, such as arthritis or problems with the veins, can cause leg pain, but the symptoms are different from PAD. By doing a physical exam and taking your medical history, your doctor can often rule out these conditions.

However, problems with nerves can cause pain that may be confused with PAD. Sometimes a nerve is squeezed where it exits the spinal column. The result is pain that radiates, or spreads, from the hips or buttocks and down the leg.

To confirm that your pain is the result of PAD, your doctor may ask you to stand up or change your position. Those movements often trigger nerve-related pain. In contrast, PAD pain is often brought on by leg exercise and is quickly relieved by rest with no need to change position.

Diagnostic tests and procedures

The ankle-brachial index (ABI) test is usually the first test used to diagnose PAD. The test compares blood pressure in your ankle with the blood pressure in your arm. Your doctor uses a blood pressure cuff and  ultrasound device for this painless test.

ankle-brachial index
The illustration shows the ankle-brachial index test. The test compares blood pressure in the ankle with blood pressure in the arm. As the blood pressure cuff deflates, the blood pressure in the arteries is recorded.

A healthy ABI result is 1.00 or greater. If you have an ABI of less than 0.90 while resting, you may have PAD. An ABI of less than 0.40 is a sign of severe PAD. If there are problems with the arteries in your ankle, your doctor may do a toe-brachial index (TBI) test instead, which measures the blood pressure in your big toe. A TBI less than 0.7 is abnormal. Be aware of your ABI, just as you know and keep track of your blood cholesterol level.

To diagnose PAD, your doctor may also order some of the following tests and procedures:

  • Blood tests to check your cholesterol, triglyceride, and blood sugar levels.
  • Exercise ABI to show the severity of your leg symptoms and the level of physical activity that produces them. Your doctor will do the ABI test after having you walk on a treadmill. This test may help your doctor diagnose PAD when you have symptoms, but your resting ABI test result is only slightly low. A drop of 20% or more in post-exercise ABI is abnormal.
  • Six-minute walking test to measure how far you can walk in a hallway in six minutes. Your doctor may do this test to see how much PAD affects your ability to function and the severity of the PAD.
  • Doppler ultrasound to locate areas of reduced blood flow or blockages and measure how fast blood is flowing through the arteries. A handheld device is passed over your skin. A computer converts sound waves into pictures of blood flow in your arteries. Ultrasound can help diagnose PAD and monitor how well PAD treatments have worked.
  • Segmental Doppler pressure testing to check different parts of your legs for narrowed or blocked arteries. This test is similar to ABI testing but uses blood pressure cuffs placed at thigh, calf, and ankle levels. The ultrasound device amplifies the sounds of blood flow in your arteries, making it easier to measure the blood pressure in these areas of your leg.
  • Computed tomography angiography (CTA) to see the arteries in your legs and feet. A special dye is injected, then X-rays are taken to show the location and extent of any blood vessel blockages.
  • Magnetic resonance angiography (MRA) to examine the structure of your leg arteries. Magnetic resonance angiography may not be safe for people who have metal implants in their body.
  • Catheter-based angiography to see inside the arteries of your legs. Your doctor inserts a catheter, or tube, into an artery in your groin and guides it to the affected area. A special dye is released through the catheter, then X-rays are taken. Your doctor may suggest this procedure for serious pain in the legs or feet or when treatments for PAD have not worked or other testing has not been helpful.