Arteriovenous Malformations

What is an arteriovenous malformation (AVM)? What does it look like?

Arteriovenous malformation

Arm and hand enlargement from arteriovenous malformations.

An AVM is a collection of abnormally formed blood vessels. Normally, arteries carry blood to blood vessels. Smaller parts of the blood vessels, called capillaries, then carry blood into tissue and veins. An AVM happens when the capillaries are missing.

Without capillaries, blood flows directly into veins at high pressure and can make the blood vessels swell under the skin. It can also make blood vessels burst and cause bleeding.

An AVM can happen anywhere in the body. It may affect a small area, such as a finger, or an entire arm or leg. AVMs can also affect internal organs, including the brain or spinal cord.  

An AVM can be visible at birth, appearing as a red stain on the skin. The skin in this area feels warmer to the touch than skin in other areas. Sometimes an AVM pulses as blood flows in and out.

AVMs are classified into 4 stages:

Stage 1: A patch of skin is reddish and may pulse.

Stage 2: The affected area is getting larger and becomes warm and tender. Enlarged veins may appear on its surface.

Stage 3: The affected area develops ulcers and starts bleeding.

Stage 4: The AVM affects the heart and can cause heart failure.

Why choose Seattle Children’s Vascular Anomalies Program?

Seattle Children’s Vascular Anomalies Program is nationally recognized. It is 1 of only 2 vascular anomalies programs on the West Coast. Doctors from across the United States send children here for treatment because of our specialized expertise. We see more children with vascular anomalies than any other hospital in the region.

Our vascular anomalies team brings together experts including otolaryngologists, dermatologists, plastic surgeons, ophthalmologists, geneticists and interventional radiologists. These doctors work together to develop a treatment plan that fits your child’s needs. We schedule your visit so your child sees all the specialists they need on the same day in the same location.

We follow your child throughout their life. Our vascular anomalies team is available to help you and answer questions.

We participate in many clinical trials and studies of new treatments that might be more effective than standard therapy. This means some of our patients get the newest treatments before they are widely available. Learn more about our research.

What causes an AVM?

AVMs seem to develop within the first 3 months of pregnancy. Doctors don’t know what causes them.

AVMs can be passed down from family members in hereditary disorders such as:

What symptoms do AVMs cause?

If AVMs on the skin aren’t treated, they slowly become larger, darker, warmer and more painful.

Pain, swelling or bleeding may develop when a child is young. The AVM might not change until puberty or young adulthood.

Advanced AVMs may also decrease movement or blood supply to an area (tissue ischemia). These symptoms often occur during and after puberty.

AVMs can make the heart work harder to push blood through damaged vessels. This can cause heart failure.

How will Seattle Children’s Diagnose an AVM?

The doctor will examine your child and ask about their symptoms. The doctor may also use the following imaging tests:

  • Doppler ultrasound to detect abnormal blood flow
  • MRI (magnetic resonance imaging) or a MRA (magnetic resonance angiography) to confirm the diagnosis, determine the AVM’s extent and help plan treatment
  • Diagnostic angiography to map blood vessels in the affected area

How will Seattle Children’s treat an AVM?

We follow our patients and monitor their condition throughout their lives. Some children may need:

  • Embolization, which is a procedure where a doctor blocks off veins around the affected area
  • Surgery to remove the abnormal blood vessels

Read Piper and Avery's stories to learn more about using glue embolization for venous malformations.

If your newborn is critically ill due to an AVM in their brain, we provide specialized care in our Neuro NICU – the only neonatal neurocritical care program in Washington, Wyoming, Alaska, Montana and Idaho.

Contact Us 

To learn more about AVM treatment at Seattle Children’s, call our Vascular Anomalies Program at 206-987-4606.