Venous malformation (VM)

What is a venous malformation (VM)?

It is usually a soft, lumpy, blue mark on the skin caused by abnormal veins. The blood vessel’s muscle layer slows down blood flow, which can lead to clots forming. Repeated clots can damage blood vessel walls and feel like hard lumps within the malformation.

They are present at birth, but might not be visible until years later. They are more noticeable when blood flow to the area increases, for instance, if a baby cries or has a raised temperature. They grow with the child and in some cases involving the arm or leg, they can cause mobility problems. 

How common are they?

VMs are quite rare and affect boys and girls equally.

Where do they occur?

As well as appearing on the skin, VMs can occur in the mucous membranes, such as the eyelids or inside the mouth, in muscles or internal organs.

How are they diagnosed?

VMs are visible in ultrasounds which show the blood flow through the veins, as well as any clots. MRI scans show the extent of the malformation and which parts of the body are involved.


Treatment will depend on the location and distribution of the VM. 

Laser therapy
Small surface malformations can be treated with a laser, which shrivels up blood vessels using heat and light.

A radiologist shrinks the blood vessels by injecting a special substance into them, making them less noticeable.

Bleomycin injection treatment
Injecting Bleomycin into a VM is an effective treatment and the response rate is 77%. 

Anti-clotting medicines such as aspirin or low-dose heparin might be suggested if required. 

Made-to-measure compression garments stop the blood pooling in the abnormal veins and encourages blood flow to the heart through normal veins. 

Surgical removal
Surgery will attempt to remove the abnormal vessel tissue, however it leaves a permanent scar and malformations can reappear after surgery. Bleeding during and after surgery is a risk because of the blood vessels involved. 

Associated syndromes

Klippel-Trenaunay syndrome
Consists of three symptoms often seen together: capillary malformation, venous malformations and limb hypertrophy (extra growth of a limb). The syndrome is present at birth although it can be difficult to diagnose until other symptoms become apparent. It affects about one in every 20,000 to 40,000 children.

Blue rubber bleb nevus syndrome
A rare disorder that consists mainly of groups of abnormally developed blood vessels called vascular malformations. These vascular malformations can affect the skin, soft tissue and internal organs of the body. 

These blue rubbery angiomas are present for a person’s entire life. They are often present at birth but new ones may appear with age. They are often first noted on the skin. They can also be found in many internal organs like the liver, spleen, lungs, and the intestines. The abnormal blood vessels in the intestines have a tendency to bleed. The bleeding may be slow but in many cases there is rapid blood loss noted in the faeces of the patient. 

This site does not provide medical advice and is not a substitute for medical or professional care, and if you see a birthmark growing or changing significantly, see a specialist.