Venous malformations are slow-flow vascular malformations due to abnormalities in the development of veins.  Venous malformations vary in size and location within the body.  When the skin or tissues just under the skin are affected, they appear as a slightly blue-coloured skin stain or swelling.  These can vary in size from time to time because of swelling within the malformation.  As these are vascular malformations, these are present at birth and grow proportionately to the child.  As some venous malformations do not involve the skin and are deeply located, there may be no colour change or swelling in the skin and the condition is identified when a scan (such as MRI or ultrasound) is done.

Venous malformations can be very small to large in size and sometimes can involve a significant area within the body, such as an entire arm or leg.  When venous malformations involve much of the muscle in an arm or leg, there may be reduced circumference of the affected body part.  Venous malformations can involve the skin, mucous membranes (such as the lining of the inside of the mouth), tissues beneath the skin, muscles, joints and bones.  Venous malformations can also increase the size of the affected body part.  When the venous malformation is well localized, this may cause localized swelling, however, when the venous malformation is more extensive, there may be more wide spread swelling of the affected body part.


Some patients with venous malformations have abnormal blood clotting within the malformation.  When a venous malformation is located within a joint, bleeding from the venous malformation into the joint can sometimes result in damage to the joint.

Most venous malformations cause no life threatening problems for patients.  Some venous malformations cause repeated pain due to intermittent swelling and congestion of the malformation or due to the formation of blood clots within the malformation.  When a venous malformation involves an arm or leg, it is likely that the affected arm or leg will have good function. Rarely, venous malformations may be part of a syndrome (an association of several clinically recognizable features) or be linked to an underlying genetic abnormality.


Patients with venous malformations who have involvement of the skin and mucous membranes can often be diagnosed by history and physical examination.  Venous malformations that are present in deeper locations are diagnosed on MRI and ultrasound scan.  These will confirm the diagnosis and provide excellent information regarding the extent of the abnormality.  Occasionally, other investigations such as blood testing are required.  Rarely, patients are referred for genetic counseling.  Venous malformations can sometimes be detected on antenatal scanning in a baby before birth.


Radiological treatments called injection sclerotherapy can be undertaken to shrink the venous malformation and to help reduce pain.  These treatments are carried out by interventional radiologists in Image Guided Therapy.  To be effective, these treatments need to be repeated, usually at frequent intervals.  Sometimes, surgical excision of the venous malformation may be possible either without or following injection sclerotherapy.


Sclerotherapy is a minimally invasive procedure which is used to treat abnormal or enlarged blood vessels, usually varicose veins. During the procedure, a solution (a special type of alcohol or foam) will be injected directly into the vessel, causing the vessel to collapse, re-routing the blood into healthier veins. The collapsed vein can eventually be reabsorbed into the body.

You will be anaesthetised for the procedure. The interventional radiologist may take one of two approaches to performing the sclerotherapy. The first possible way to carry out the procedure is by inserting catheters into a blood

vessel and then injecting a solution of 90% alcohol into the affected vein, causing the vein to become blocked. This is known as an endovascular approach.

The other way in which the interventional radiologist may perform the procedure is a percutaneous approach. For this approach, the interventional radiologist directly injects the solution into the selected vessel or vessels, usually guided by sonography.

Recently, other minimally invasive alternatives have been used as alternatives for patients undergoing sclerotherapy, such as laser or cryoablation.
Sclerotherapy is recommended as a treatment as it has a higher rate of success than other methods.
Venous malformations can occur anywhere within the body and not all require specific treatment. Many can be treated by injection sclerotherapy alone or in combination with surgery. A few venous malformations may be suitable for surgical excision alone. As venous malformations can involve skin, mucous membranes (such as the lining of the inside of the mouth), tissues beneath the skin, muscles, joints and bones, surgery may be difficult and injection sclerotherapy may be a preferred option. As venous malformations can surround nerves and vital structures, surgery may not be an option.