Venous malformation

Veins are blood vessels that carry low-pressure blood from the tissues back to the heart. A venous malformation occurs when veins in a part of the body are formed abnormally before birth. The malformed veins are usually missing muscle in their walls, causing them to gradually expand or enlarge and form masses or areas of swelling. When the major veins are affected, their valves may not function, causing venous insufficiency. When the skin is involved, it appears blue to deep blue/purple. Because of slow blood flow, blood clots can form in the venous malformation. The clots may be painful, and can lead to further swelling. These blood clots do not usually travel to other parts of the body.

Where do venous malformations appear?

They can appear anywhere on the skin or inside your body, anywhere from head to toe. The venous malformation may be small or may affect an entire arm or leg.. The swelling usually feels soft to touch, worsens when the affected area is lower than the rest of the body and improves when the affected area is raised above the heart. Rapid enlargement can take place during puberty and pregnancy. They are present at birth and may run in families. Some genetic mutations are known to cause venous malformations. If the venous malformation is deep in the muscle, it may go unnoticed for years.

How do doctors diagnose venous malformations?

A venous malformation is confirmed by an MRI or an ultrasound test. The doctor may also want to do a small skin biopsy.

  • An MRI scanner uses a large magnet, radio waves and a computer to take pictures of inside the body. It does not use radiation. It is the best test to show how large or extensive the venous malformation is. Contrast medium injected into a vein is usually needed to complete the test.
  • An ultrasound uses sound waves to make pictures of the body. Your child will not hear or feel the sound waves. It is not an X-ray and does not use radiation.

venous malformationWhat problems could the malformation cause?

  • Painful swelling, often in the morning or after exercise or when the affected area is dependent.
  • When the airway is involved, venous malformation can make it difficult to breathe.
  • Bleeding can occur, especially when the venous malformation is in the bowel.
  • Extensive venous malformations can consume the blood clotting proteins, causing a tendency to bruise easily or bleed.

How are they treated?

A venous malformation does not need to be treated if it is not causing any problems, but it will not go away without treatment.

  • Compression therapy - A tight-fitting stocking or other garment is sometimes used to decrease swelling and prevent blood from pooling in the abnormal veins. Special pumps put on the outside of the skin can be used to help the blood flow better.
  • Pain medicine, antibiotics, or raising the arm or leg - These help with pain, swelling, infection and bleeding
  • Blood thinning medicine - This keeps the blood from clotting and helps with the pain caused by clots
  • Sclerotherapy - In an interventional radiology suite, image guidance is used to inject sclerosing medication into the abnormal veins. This will damage the veins and cause them to close, so blood no longer pools in them. The malformed veins will then collapse and form scar tissue.
  • Surgery - In some cases, the affected area may be removed. This depends on where the malformation is, if it is causing pain or if it affects movement.
  • Sometimes surgery and sclerotherapy are used together.

Other helpful resources:

  • Mulliken JB, Burrows PE and Fishman SF. Mulliken and Young's Vascular Anomalies. Hemangiomas and Malformations second edition. Oxford University press 2013
  • Blei F, Anglin C. 100 Questions and Answers about Vascular Anomalies. Jones and Bartlett publishers 2011


Call your child's doctor, nurse, or clinic if you have any concerns or if your child has:

  • Bleeding that will not stop
  • An infection that does not heal
  • Pain that does not get better with pain medicine
  • Special health care needs not covered by this information
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