Sclerotherapy of Varicose Veins

Sclerotherapy is the art of treating abnormal leg veins by injecting them with a sclerosant (corrosive) agent which causes disruption to the internal lining of the injected vein.  The result is fibrosis of the injected vessel and eventual absorption of the vessel by the body.

There are 2 forms of sclerotherapy – microsclerotherapy and ultrasound guided foam sclerotherapy.  Both forms of sclerotherapy use sodiumtetradecyl sulphate and Aethoxysklerol (or Polidocanol) as the sclerosing agent.  Concentrations of each of the agents used vary and depend on the size of the vessel being treated.


Sclerotherapy is still the gold standard for treating spider or thread veins on the legs. Lasers have been used, but the results are not as good as sclerotherapy possibly because with sclerotherapy, “feeder” veins are also sclerosed in the process of treating spider veins. Laser ablation of veins is far more successful treating facial veins.

Microsclerotherapy involves injecting the sclerosant solution directly into the offending veins by direct vision. It takes approximately 4 weeks to see the outcome of 1 treatment session. Not all veins will respond to a single treatment session and most patients require a minimum of 2 treatment sessions. Each treatment session lasts approximately 30 mins. The treatment is not pain-free – it is bearable and most patients are able to tolerate the pain of injecting for 30 mins. One leg is treated per session. A Class II compression stocking is worn for a full week post treatment.

Ultrasound guided foam sclerotherapy

With the introduction of ultrasonography in the 1980’s and sclerosant foam in the late 90’s, ultrasound guided foam sclerotherapy became the treatment of choice for the non-surgical treatment of varicose veins. Once a map of the varicose veins is done with the aid of the ultrasound, the foamed sclerosant is injected directly into the diseased vein. The foam is prepared by mixing the sclerosant solution with carbon dioxide gas and injected into the vein. Foam sclerotherapy is more effective than liquid sclerotherapy because the bubbles create an increase in surface area of the sclerosant and unlike the liquid which tends to become diluted by blood in the vein, foam tends to displace blood, causing thickening of the vessel wall and fibrosis. This is a relatively painless procedure and also requires the use of a compression stocking for 2 weeks.


More common complications include:

  • Bruising
  • Swelling
  • Trapped blood – these are tender lumps of clotted blood that occur because flow of blood has been stopped by the sclerosant sealing off the vein.  These localised clots of blood do not travel.  Small tender lumps will resolve slowly, larger lumps need to be evacuated.
  • Pigmentation – Brown stain of varying darkness can occur post-sclerotherapy either associated with or independent of trapped blood.  This is due to Haemosidderin or iron in blood staining the skin.  In about 90% of cases this improves with time, sometimes persisting for 12 months.  Evacuating trapped blood also speeds up the resolution.
  • Ulceration – quite uncommon, often related to strength of sclerosant, injection technique.  They always heal, but are often painful and may take 5 to 6 weeks to resolve.
  • Thrombophlebitis – An inflammatory reaction in the vein from treatment.  It is tender, can be painful and causes redness – often mistaken for infection and treated with antibiotics.  Responds to wearing compression stocking and taking an anti-inflammatory medication.
  • Visual disturbance/migraine – usually occurs in those individuals who are prone to migraine headaches.  It is thought to be more likely to occur with foam than liquid sclerotherapy.  The mechanism of action is thought to be due to the release of vaso-active substances e.g. “Endothelin”,  from the inner lining of veins (Endothelium).  Usually spontaneously resolves within 20-30 mins or with the use of standard migraine medications.
  • Deep Vein Thrombosis (DVT) – This is a very rare occurrence following sclerotherapy.  Instances of DVT, Pulmonary Embolus and stroke have been reported in the literature but are rare. Pulmonary Embolus and Stroke are more likely in those subjects who are known to have a septal defect in their heart (also known as “hole in the heart”) – sclerotherapy is NOT recommended for these individuals.
  • Anaphylaxis – these are usualy non-fatal and symptoms may include rash, dizziness, wheezing, tachycardia (fast heart rate), vomiting, abdominal pain and nausea.  Incidence ranges from 0.01% to 0.1%.

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