Tests and diagnosisBy Mayo Clinic staff
To diagnose an arteriovenous fistula, your doctor will use a stethoscope to listen to the blood flow through the area where he or she thinks you may have a fistula. The blood flow through an arteriovenous fistula makes a sound similar to clicking or humming machinery (machinery murmur).
If your doctor hears a machinery murmur, you'll have other tests to confirm that the murmur is caused by an arteriovenous fistula. These can include:
- Duplex ultrasound. Duplex ultrasound is the most effective and common way to check for an arteriovenous fistula in the blood vessels of the legs or arms. In duplex ultrasound, an instrument called a transducer is pressed to your skin. The transducer produces high-frequency sound waves, which bounce off red blood cells. A duplex ultrasound can estimate how fast blood flows by measuring the rate of change in its pitch (frequency).
- Computerized tomography (CT) angiogram. A CT angiogram allows your doctor to check your arteries to see if blood flow is bypassing the capillaries. You'll receive an injection of a dye that shows up on CT images, and the doughnut-shaped CT scanner will be moved to take images of the artery your doctor believes is narrowed. The images are then sent to a computer screen for your doctor to view.
- Magnetic resonance angiography (MRA). Your doctor may use MRA if he or she thinks you may have an arteriovenous fistula in an artery that's deep under your skin. This test allows your doctor to see the soft tissues in your body. It uses the same technique as magnetic resonance imaging (MRI), but also includes the use of a special dye that helps create images of your blood vessels. During an MRI or MRA, you lie on a table inside a long tube-like machine that produces a magnetic field. An MRI machine uses the magnetic field and radio waves to create pictures of your body's tissues. Using the images from the test, your doctor may be able to see an arteriovenous fistula.
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