Arteriovenous Malformations

What is an arteriovenous malformation (AVM)?

Arteriovenous malformation

Arm and hand enlargement from arteriovenous malformations.

Arteriovenous (are-TEAR-ee-oh-venus) malformations (AVMs) are tangles of blood vessels (arteries and veins). Normally, very small tubes (capillaries) connect arteries to veins. An AVM happens when the capillaries are missing. Without capillaries, blood from an artery flows under high pressure directly into a vein. This can make the blood vessels swell under the skin. It can also cause them to burst and bleed. An AVM can limit your child's ability to move and may cause other serious health problems. 

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.  

  • What causes an AVM?

    The exact cause is not known. Some AVMs are caused by genetic changes (called mutations or variants) that happen early in pregnancy. The mutation starts in 1 cell. Any cells that divide from that cell will continue the mutation. This is called a mosaic mutation. The abnormal gene is not passed down by parents (not inherited).

    AVMs may be a symptom of a syndrome like Proteus syndrome. AVMs may develop as part of a condition passed down from parent to child (inherited), such as Parkes-Weber syndrome or hereditary hemorrhagic telangiectasia (HHT).  

AVMs at Seattle Children's

Our Vascular Anomalies Program is nationally known for treating children with AVMs and other vascular disorders. We are 1 of the largest and most experienced programs in the United States.

Doctors from across the United States send children here for treatment because of our specialized expertise. We see nearly 2,000 children with vascular anomalies each year, more than any other hospital in the region.

For more information, contact the Vascular Anomalies Program by email or by calling 206-987-4606. If you would like an appointment, ask your child’s primary care provider to refer you.

Providers, see how to refer a patient

  • The experts you need are here
    • We have treated hundreds of children for AVMs. Doctors with less experience might confuse an AVM with another type of vascular anomaly, leading to the wrong treatment.
    • Our Vascular Anomalies team brings together experts with many different skills and experiences. These include otolaryngologists, plastic surgeons, neurosurgeons, general surgeons, orthopedic surgeons, interventional radiologists and geneticists. Your child will also be treated by experts in any body system the AVM affects, such as lungs (pulmonologists), skin (dermatologists) or eyes (ophthalmologists).
    • Our physician-scientists help set national standards for care of young people with vascular anomalies. We provide the most advanced treatments in our region.
    • For babies who are very sick because of an AVM in their brain, we provide specialized care in our Neuro NICU. Seattle Children’s has the only neonatal neurocritical care program in Washington, Wyoming, Alaska, Montana and Idaho.
  • Accurate diagnosis and precision medicine
    • A correct diagnosis is the first step toward improving your child's condition. We have the expertise to accurately diagnose your child’s AVM. If tests are needed to confirm it, we have a broad range of options, such as genetic testing and imaging studies. These tests help us work with you to decide the best treatment option for your child.
    • Our physician-scientists have created a way to test patients’ tissue and body fluids for the genetic changes known to cause vascular anomalies. The test is called a gene panel. We can test DNA in tissue sent to us from doctors across the nation. No other children’s hospital has a gene panel certified for clinical use with vascular malformations. This certification means doctors can make treatment decisions based on the results.
    • The gene panel may help identify a genetic cause of an AVM in some children. A precise diagnosis may expand your child’s treatment options to include drugs that target the overactive biological pathway causing the malformation. These targeted therapies may be newly developed or already approved for other diseases.
    • Our genetic testing expertise helps us create new therapies that we offer in research studies called clinical trials.
    • Learn more about vascular anomalies research at Seattle Children’s.
  • Making treatment easier on your child
    • Until Seattle Children’s pioneered glue embolization surgery (GES), many children with vascular malformations had no treatment options except for repeated, painful injections or multiple surgeries. Now, some children with AVMs can be treated in a single surgery (GES).
    • For children who need surgery to remove an AVM in the face, we use facial nerve mapping. This greatly reduces the risk of nerve injury and scarring.
  • Team approach for complete care
    • We schedule visits so your child sees all the specialists they need in as few days as possible. In some cases, we can consult via video phone calls with doctors or patients.
    • Your child’s team will work together – and with you – to make a treatment plan that fits your child’s unique needs. Combining our skills helps make sure your child gets the very best care.
    • As long as needed, our team keeps a watch on your child’s condition. We are always here to answer your questions and connect you to community resources.
  • Among the nation’s best children’s hospitals
    • Children do not react to illness, injury, pain and medicine in the same way as adults. They need – and deserve – care designed just for them. Our experts focus on how treatments today affect growing bodies in the future. We provide the best and safest treatment for your child, based on our years of experience and the newest research.
    • At Seattle Children's, we work with children and families from around the Northwest and beyond. Whether you live nearby or far away, we can help with financial counseling, schooling, housing, transportation, interpreter services and spiritual care. Read about our services for patients and families.

Symptoms of AVMs

Many AVMs are not noticed until later in life. But some can be seen in newborns.

AVMs cause different symptoms depending on where they are:

  • In the skin or mucous membranes, an AVM may bleed or pulse as blood flows in and out of the area. An AVM may look like a bruised bump under the skin that is warm to the touch or tender.
  • In an arm or leg, an AVM may cause swelling, pain or weakness. It may limit your child’s motion.
  • An AVM in the lining of the stomach or intestines (gastrointestinal or GI tract) may cause bleeding. This can range from mild to severe. Your child may vomit up blood or have dark, tarry bowel movements.
  • In bone, an AVM may erode the affected area.
  • In the lungs, an AVM may cause your child to be tired, short of breath or cough up blood.
  • In the brain, symptoms of an AVM depend on the part of the brain that is affected. Your child could have headaches, seizures or problems with their hearing, vision or speech.

AVMs change and grow over time. As your child grows, an AVM can hurt, swell or bleed. Starting at puberty or young adulthood, it may cause more problems. Depending on where the AVM is located, it may affect the normal function of your child’s body, such as:

  • Reduce blood supply to an area (tissue ischemia)
  • Limit movement
  • Affect your child’s weight and growth
  • Cause congestive heart failure

Diagnosing AVMs

To diagnose an AVM, the doctor will:

  • Examine your child
  • Ask about their symptoms

The doctor may also take pictures of the inside of your child’s body (imaging studies) with:

  • Doppler ultrasound to check blood flow
  • MRI (magnetic resonance imaging) or MRA (magnetic resonance angiography) to confirm the diagnosis, find out the extent of the AVM and help plan treatment
  • Diagnostic angiography to map blood vessels in the affected area
  • CT (computed tomography) scan or CT angiogram if the AVM is next to a bone

We have created a way to test a patient’s tissue for genetic changes (variants or mutations) known to cause vascular anomalies. Genetic testing results may help:

  • Inform your child’s diagnosis
  • Alert us to screen for other conditions like HHT
  • Guide treatment decisions

Diagnosing an AVM early is important so we can ease your child’s symptoms and avoid serious problems. The doctors will work with you and your child to decide on a treatment plan. 

AVMs are classified into 4 stages:

  • Stage 1: A patch of skin is discolored 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 sores and starts bleeding.
  • Stage 4: The AVM affects the heart and can cause heart failure.

Treating AVMs

The best treatment for your child depends on the size and location of their AVM and whether it causes pain or problems in the affected part of their body.

Rarely, a baby born with an AVM in the brain needs care right away. If your newborn is critically ill due to an AVM in their brain, we will care for them in our Neuro NICU.

We watch your child closely throughout their life. If treatment is needed, we review options with your family and come up with the best plan for your child.

  • Regular check-ups

    We check your child at regular follow-up visits. How often we see your child depends on their symptoms. 

    We talk with you about the best way to track your child’s AVM. Some children need regular imaging studies to track the AVM’s growth and how it affects nearby areas of the body.

    Treatment options may change as your child’s AVM changes. We partner with you to decide the best care for your child.

  • Medicine

    AVMs are sometimes managed with medicines to treat symptoms like pain or bleeding.

    If genetic testing identifies a genetic cause for your child’s AVM, your child’s treatment options may include drugs that target the overactive biological pathway causing the malformation.

    Your doctor will discuss the benefits and risks of each medicine. Your healthcare team will watch your child closely while they are taking these medicines.

  • Embolization

    Embolization is a way to stop blood flow. Watching on video screens that show your child’s AVM in real time, an interventional radiologist:

    • Inserts a small tube (catheter) into a blood vessel.
    • Threads it to the target area.
    • Injects a substance to block blood flow in the area. The substance may be medical-grade Super Glue or tiny coils or plugs.
  • Surgery, including glue embolization

    Often surgery to remove or reduce the size of the AVM is the best option. We consider surgery based on your family’s wishes and whether the AVM:

    • Causes symptoms like pain or bleeding
    • Makes it hard to see, breathe, move or do other important functions
    • Affects your child’s appearance much

    Surgery may not be possible if the AVM is widespread or surrounds important body parts and organs. Sometimes we can only remove part of an AVM.

    Often we use glue embolization surgery (GES) to remove or reduce AVMs. Our doctors were the first to use medical-grade Super Glue to remove the tangle of extra veins in a single surgery.

    • Before the procedure, we give your child medicine so they sleep without pain (general anesthesia).
    • Watching on monitors that show your child’s AVM in real time, an interventional radiologist places the needle in exactly the right spot. This assures that only the abnormal veins are injected with glue.
    • The glue hardens the AVM without harming the tissue around it.
    • Using a low-dose CT scan, we make a 3-D image to guide surgeons during the delicate procedure.
    • Surgeons remove the AVM, with the glue inside.

    At Seattle Children’s, glue embolization surgery is an option for children with AVMs in many parts of the body.

    We map nerves to make surgery safer when removing AVMs in the head. Before surgery, we use small electric pulses to pinpoint the facial nerves. During the procedure, real-time feedback about nerve activity helps guide surgeons. The technique means shorter surgery time, with smaller cuts and near-zero risk of nerve injury.

  • Treating brain AVMs

    AVMs in the brain can be life-threatening or disabling if they bleed. Proper diagnosis and screening are essential.

    The right treatment depends on the AVM’s size, structure and location. Your child may need surgery, embolization or stereotactic radiosurgery, alone or together.

    Read about treating AVMs and other vascular diseases of the brain.

  • Clinical trials

    For some children, genetic testing helps doctors identify the exact genetic cause of their AVM. Such a precise diagnosis may expand treatment options to include drugs that target the overactive biological pathway causing the malformation. If this is the case for your child, our doctors will talk with you about the options and any research studies (clinical trials) that might be a good match.

Contact Us

If you have questions about a consultation or second opinion, email us or call 206-987-4606.

If you would like an appointment, ask your child’s primary care provider to refer you.

Providers, see how to refer a patient

Related Links

Paying for Care

Learn about paying for care at Seattle Children’s, such as insurance coverage, billing and financial assistance.

For Healthcare Professionals