Diagnosis

Your doctor will use a stethoscope to listen to the blood flow in your arms and legs. The blood flow through an arteriovenous fistula makes a sound similar to humming.

If your doctor suspects a fistula, you'll have other tests to confirm your diagnosis. Tests to diagnose an arteriovenous fistula can include:

• Duplex ultrasound. Duplex ultrasound is the most effective and common way to check for an arteriovenous fistula in your legs or arms. In duplex ultrasound, sound waves are used to evaluate the speed of blood flow.
• Computerized tomography (CT) angiogram. A CT angiogram can show if blood flow is bypassing the capillaries. Before the test starts, you'll receive an injection of a dye (contrast) that makes your blood vessels show up more clearly on CT images.
• Magnetic resonance angiography (MRA). Your doctor may use this test if he or she thinks you have an arteriovenous fistula deep under your skin. Like an MRI, an MRA uses a magnetic field and radio waves to create pictures of the body's soft tissues. However, you're also given a special dye that helps create images of your blood vessels.