Sclerotherapy is an injection of a sclerosing (e.g., alcohol) substance directly through the skin into a lesion and is used primarily for slow-flow vascular anomalies, particularly for venous malformation (cavernous hemangioma) and lymphatic malformation (cystic hygroma).  This procedure is performed by interventional radiologists (Staff Radiologist in Interventional Radiology or minimally invasive imaging-guided therapy) who have experience with vascular anomalies. Various needles are used under ultrasound guidance to obtain access and then the sclerosant agent is injected into the lesion very carefully (CT guided sclerotherapy is explained below).  


Sclerotherapy Procedure

Typical procedure room (photo 1). The sclerosant agent preparation (photo 2).  Injection of sclerosant agent under ultrasonography guidance (photo 3). Ultrasonography is the most commonly used imaging modality for guidance during sclerotherapy. Photo#4 shows contrast opacification of a venous malformation (cavernous hemangioma) lesion under fluoroscopic guidance. This direct venograms should be performed during the sclerotherapy to assess the malformation morphology, as well as the draining veins of the malformation to perform sclerotherapy safely. 



First image is a radiographic image showing percutaneous contrast injection into the malformation. The malformation in the upper calf behind the knee. The lesion demonstrates inhomogeneous filling without any significant venous drainage into the deep veins. A second image is a different patient, again percutaneous contrast injection into the malformation, demonstrating a single draining vein. This vein needs to be closed off before any sclerosant substance injection. 3rd image is also a radiographic image after the sclerosant injection (same patient, 1st image). Final image is a different patient with a large venous malformation (slow-flow vascular birthmark) in the thigh after sclerotherapy.

If there are draining veins, the veins should be temporarily (using manual compression or blood pressure tourniquet) or permanently closed off (venous embolization) before the injection of the sclerosant agent so that the substance will be maintained within the lesion. Absolute alcohol (ethanol) is the most commonly used sclerosant agent because of its superior ability to cause endothelial damage and induce thrombosis and sclerosis. Major potential risks of alcohol injection include nerve damage, cardiovascular toxicity and skin necrosis. Therefore, the procedure should be planned carefully and be performed only by an experienced interventional radiologist.

Photo 1 shows the malformation on fluoroscopic image following sclerosant injection. Photo 2 shows the leg at the end of the procedure.

Weaker sclerosant agents such as sodium tetradecyl sulfate (Sotrecol) or ethanolamine oleate (Ethamolin) are considered safer sclerosant agents in terms of skin necrosis, neurotoxicity and cardiovascular effects.  After sclerotherapy, particularly when using alcohol, the lesion feels firm to palpation and the injected area shows significant swelling and pain. Maximum swelling occurs within the first 24 hours after the procedure and decreases gradually. 

Sclerosant Agents

  •   Ethanol (Alcohol) is an ideal agent for venous and lymphatic malformations (vascular birthmarks). Sclerotherapy with absolute alcohol has a direct toxic effect on the endothelium that activates the coagulation system and causes the microaggregation of red blood cells. Occlusion of the lumen occurs within minutes or days. Ethanol can be damaging if it reaches the capillary bed of any given tissue (eg, skin), and it usually causes significant soft-tissue swelling, which may subsequently cause compartment syndrome (nerve compression). If large amounts of absolute alcohol enter the systemic circulation, toxic effects can occur. These include central nervous system (CNS) depression, hemolysis, and cardiac arrest. Slow, careful injections by using balloon occlusion arterial catheters for delivery and by applying manual compression on the draining veins (or tourniquet control) or balloon occlusion of the draining system may decrease alcohol washout from the lesion and reduce acute systemic toxicity. Ethanol 1 mg/kg is the maximum amount that can be injected during a single session.
  •   Sodium tetradecyl sulfate (Sotradecol) is another sclerosant, commonly used for venous and lymphatic malformations (vascular birthmarks). This contains 2% benzyl alcohol and is commonly used for venous malformations and varicose veins. Use of this agent is less painful for the patient, and it is considered to be less toxic then absolute alcohol.  Some lesions can be treated without general anesthesia.  Sodium tetradecyl sulfate can be used as a sclerosant in various concentrations (1-3%); however, manufacture of this agent has been discontinued in the United States. Recently, we have begun using ethanolamine oleate (Ethamolin; Questcor Pharmaceuticals, Hayward, Calif) instead of sodium tetradecyl, with the same indications.
  •   Doxycycline is an antibiotic medicine belonging to the class called "tetracyclines." It is used to treat bacterial infections in many different parts of the body.  It is an effective sclerosant agent for lymphatic malformations (cystic hygroma lesions). Doxycycline and other members of the tetracycline class of antibiotics are not generally approved for treating patients under 8 years old (Tetracycline antibiotics are associated with permanent tooth discoloration in children).
  •   OK-432 is a lyophilized biological preparation containing the cells of Streptococcus pyogenes.  This  sclerosant agent particularly useful for lymphatic  malformations (cystic hygroma lesions). Shrinkage of the lesions is usually noted around  5 to 6 weeks after the previous injection of OK-432. The mechanism of this therapy is uncertain. Presently, OK-432 has not been approved by the FDA. For more information on OK-432
  •                    - Dr. Shuhei Ogita's site
  •                    - PDF file - research paper on treatment of lymphangiomas with OK-432 (Picibanil)



MR image (image#1) showing a lymphatic malformation (cystic hygroma) at he base of the tongue (bright tissue) and the lesion is almost disappeared after sclerotherapy with doxycycline (image#2). 

CT & Fluoroscopy-guided Sclerotherapy Procedure


1st image is an axial T2 weighted MRI. Venous malformation is a relatively small venous malformation (low-flow birthmark) in the medial upper thigh. 2nd image is a T1 weighted MRI demonstrating increased fat tissue within the diseased area. This is a common association with vascular birthmarks. 3rd image is a CT image again demonstrating increased fat in the lesion and also calcifications consistent with phleboliths. This is a low-flow vascular anomaly or birthmark and needs to be treated with sclerotherapy under imaging guidance. The lesion could not be detected with ultrasonography; therefore, a CT guidance was used.


1st image is a CT image obtained during coil deployment under CT. A needle was inserted into the malformation and a tiny metal coil was deployed. In this case, total of 4 coils were used to guide the subsequent fluoroscopy-guided sclerotherapy procedure. The patient was transferred to the procedure room and a radiographic film (2nd image) demonstrates 4 tiny coils outlining the malformation. Using these coils, percutaneous access was gained into this birthmark and sclerotherapy was performed (3rd image) using absolute alcohol. Conclusion: In cases, ultrasonography can not be used for guidance, the lesion can be marked with tiny coils using CT and the coils then can be targeted during sclerotherapy. 

It is important to monitor patients for compartment syndrome and neurological deficits after the procedure. Airway protection is also mandatory when a lesion involving the airway is treated with sclerotherapy. Skin blistering is a common occurrence and may result in scarring. 


                        Skin necrosis after sclerotherapy (Photo #1 & 2)



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