Vascular Malformations

What are vascular malformations?

Vascular malformations are a rare group of conditions that are best described as “birth marks”. They are broadly divided into two groups; low flow malformations and high flow malformations. Low flow malformations are subdivided into low flow venous (venous malformation), low flow lymphatic (lymphatic malformation) or mixed and are by far the commonest seen. The vast majority of vascular malformations are asymptomatic (cause no problems) although some present with a painful lump that requires treatment. Accurate diagnosis is key to management and to exclude a more sinister pathology (e.g. cancer).

The majority of vascular malformations are present at birth and are due to minor abnormalities of development in the womb. Most vascular malformations do not require active treatment, just advice regarding the diagnosis and natural history. Some however do cause localised symptoms and this commonly occurs during adolescence when children are growing fast. Vascular malformations are due to a “field defect” and the cells are predetermined to always make the abnormal area even if it is removed by surgery. Because of this treatments have been developed to be minimally invasive and treat the symptoms to improve the quality of life. The treatment is often called Direct Stick Sclerotherapy.

What is Direct Stick Sclerotherapy?

Direct stick sclerotherapy (DSS) is a procedure to treat vascular malformations. A liquid agent (sclerosant) is injected through a needle into the swelling to cause it to shrink. The liquid agent is often delivered as foam, which affords better contact of the sclerosant with the lining cells. The aim is to reduce the size of the malformation and thereby reduce the symptoms usually over a course of treatment, 3 or more sessions. Other imaging tests will usually have been performed (such as a magnetic resonance imaging [MRI] scan and an ultrasound scan) to aid the diagnosis and will have helped in deciding the best form of treatment in your case. Vascular malformations are made up of spaces (blood or lymph) and matrix (solid components) and can be macrocystic (large spaces) or microcystic (small spaces). Direct stick sclerotherapy is best for the macrocystic lesions although in some cases it can be used in microcystic lesions. Other agents are available for the treatment of microcystic vascular malformations, which work in a different way – the most common is Bleomycin sclerotherapy.

When do patients require Direct Stick Sclerotherapy?

Patients present in many different ways but commonly a swelling is noticed, occasionally this swelling can fluctuate and be painful under some circumstances. Initially this can be quite frightening as doctors often worry about cancer, however, vascular malformations are benign. The diagnosis is made by history, examination and imaging. The most important imaging is Ultrasound and MRI which can often make the diagnosis. Very occasionally there remains uncertainty regarding the swelling and a biopsy is then performed to ensure the correct diagnosis. Only those patients who are symptomatic or in a visible area e.g. the face and whose quality of life is being impaired are considered for treatment. The treatment is aimed at trying to shrink the abnormality and reduce symptoms to allow normal activities.


What happens during Direct Stick Sclerotherapy?

You will be asked to get undressed and put on a hospital gown. A small cannula (thin tube) will be placed into a vein in your arm. You will be asked to lie flat on your back on the X-ray table. You may have monitoring devices attached to your chest and finger and may be given oxygen. Direct stick sclerotherapy is performed under sterile conditions and the interventional radiologist and radiology nurse will wear sterile gowns and gloves to carry out the procedure. The skin overlying the swelling will be prepped with antiseptic and you may have a small injection of a sedative to make you feel sleepy. Using ultrasound guidance, several small needles will be placed in the swelling, occasionally a small amount of dye (contrast agent) is injected to confirm the needle is correctly positioned and to calculate the correct volume of sclerosing agent to inject. At other times ultrasound alone is used to watch the foam fill the abnormality. The liquid or foam sclerosing agent is injected and the procedure is finished. Sometimes it is not possible to place a needle in a safe position and the procedure has to be abandoned.

How should I prepare?

The procedure will most likely be carried out under local anaesthesia as an adult (possibly with a light sedative) and a general anaesthetic as a child. The procedure is generally carried out as a day case. You may be asked not to eat for 4hrs before the procedure, although you may still drink clear fluids such as water. If you have any allergies or have previously had a reaction to the dye (contrast agent), you must tell the radiology staff before you have the test.