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​Vascular Malformations

Vascular malformations are abnormal connections between blood or lymph vessels. They are typically present at birth (congenital) but may also develop during one’s lifetime.

At the UPMC Heart and Vascular Institute, we take a team-based approach to diagnose vascular malformations. Drawing upon the expertise of a diverse group of specialists, we then develop the most effective treatment.

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What Are Vascular Malformations?

Vascular malformations can occur anywhere in the body, including your:

  • Arms and legs
  • Skin
  • Body cavities
  • Brain and spinal cord

Arteries, capillaries, and veins

Arteries are blood vessels that travel away from the heart. They carry oxygen- and nutrient-rich blood to the body's tissues.

From arteries, blood flows into arterioles, then into capillaries.

Capillaries — blood vessels with thin walls — serve as a bridge between arteries and veins.

Veins carry oxygen- and nutrient-poor blood back to the heart and lungs.

The thin walls of the capillaries allow the body's cells to absorb oxygen and nutrients, and blood cells to pick up waste products — such as carbon dioxide — from the body's cells.

Blood that is low in oxygen travels through capillaries into venules. Venules join to form veins. Blood travels to the heart through veins.

Vascular malformation causes and complications

The exact cause of vascular malformations is unknown. They affect men and women equally.

Abnormal vessels can cause problems with the normal flow of blood by preventing enough oxygenated blood to fill the capillaries.

In some people, blood vessels form and grow in a way that causes blood to go directly from arteries to the veins without ever reaching the capillaries.

When blood does not fill capillaries, it creates a lack of oxygen and a buildup of waste in the body tissue that would normally get blood from those capillaries.

Types of vascular malformations

Doctors group vascular malformations based on their location in the body, and the type of abnormally formed blood vessel.

Vascular malformations can occur between:

  • Veins only — called venous malformations.
  • Lymph vessels only — called lymphatic malformations.
  • Both veins and lymph vessels— called venolymphatic malformations.
  • Arteries connected to veins — called arteriovenous malformations.

Doctors also categorize malformations by how much blood flows through them, including:

  • High-flow — often called vascular malformations —involve abnormal connections between arteries and veins.
  • Low- flow — involve abnormal connections between veins and other veins or lymph vessels.
  • Mixed vascular malformations — have parts of fast high and low flow malformations. They may also become apparent following an injury, during puberty, or during pregnancy.

Vascular Malformation Symptoms and Diagnosis

Symptoms of vascular malformations depend on their size and location.

The most common symptoms include:

  • Pain
  • Swelling
  • Skin discoloration color in the area of the malformation

Some people with high-flow vascular malformations can become short of breath and tire easily during activities.

The skin over a vascular malformation may be warm and discolored. In addition, skin could:

  • Become tender
  • Bleed
  • Bruise easily
  • Break down

Diagnosing vascular malformations

Your doctor at the UPMC Heart and Vascular Institute will diagnose a vascular malformation during a physical exam. He or she may recommend imaging tests to confirm the diagnosis, better evaluate the malformation, and plan treatment.

These tests include:

  • Ultrasound uses sound waves to create images of the structures of your body. This test can give your doctor a picture of the vascular malformation.
  • Angiography/venography is an x-ray of the blood vessels. Your doctor injects a contrast dye into your blood vessels. The dye blocks x-rays from passing through the blood dye, which enables your doctor to see your blood vessels and the vascular malformation more clearly on the x-ray.
  • Computed tomography (CT) scan transmits x-rays to a computer. The computer translates the x-ray information to create cross-sectional views of your body. Your doctor may use contrast dye to enhance the images of your blood vessels.
  • Magnetic resonance imaging (MRI) uses radio waves to create two-dimensional images of your blood vessels. 

Learn more about vascular malformation testing

UPMC Patient Education Materials:

Vascular Malformation Treatment

At the UPMC Heart and Vascular Institute, we take a multidisciplinary approach to the diagnosis and treatment of vascular malformations.

Your treatment team may include:

  • Vascular surgeons
  • Interventional radiologists
  • Dermatologists
  • Orthopaedic specialists
  • Plastic surgeons

We provide a range of treatment options for vascular malformations, and we tailor our treatment recommendations to your individual needs to ensure you receive the right treatment for you.

The goal of treating vascular malformations is to decrease the symptoms and the size of the malformation or malformations.

Compression therapy

If the malformation is located in an arm or leg, your doctor may recommend compression therapy. Compression therapy works by squeezing the limb to prevent the vessels from filling completely, which decreases swelling.


In sclerotherapy, your doctor injects a chemical solution (sclerosant) into the vascular malformation. The chemical causes the vessels of the malformation to scar and collapse. Your body eventually reabsorbs the collapsed vessels and reroutes the blood flow to other blood vessels.

Most vascular malformations require several sclerotherapy sessions over a period.

Sclerotherapy may not cure the malformation, but will decrease the size of the malformation and can help decrease symptoms.


Embolization permanently blocks blood from flowing through the vascular malformation.

Your UPMC doctor can perform the procedure by injecting an embolic agent such as:

  • Glue
  • A glue-like substance called Onyx
  • An antibiotic
  • Small beads
  • Metal coils
  • A combination of liquid sclerosing agents

Many vascular malformations are large and will require more than one procedure to reduce the symptoms.

Surgery to remove vascular malformations

Your UPMC vascular surgeon can remove a vascular malformation via surgery, the goal of which is to decrease the size of the malformation. Because it is more invasive than other treatments, surgery usually requires more recovery time. 

Learn more about vascular malformation treatment

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