Foam sclerotherapy (FST) is a minimally invasive procedure used primarily to treat varicose veins and other forms of venous insufficiency. The treatment involves injecting a sclerosant solution mixed with air or gas to create a foam consistency. This foamed sclerosant is injected directly into the diseased vein, displacing the blood and irritating the vein wall. This irritation causes the vein to collapse, close, and eventually be absorbed by the body. While FST is generally considered safe and effective when performed correctly, patients should be aware of expected temporary side effects and rare, more serious complications.
Understanding the Procedure and Expected Side Effects
The mechanism of FST relies on the foam maximizing contact with the vein wall, creating a chemical reaction that leads to the vessel’s permanent closure. This chemical irritation and subsequent closure result in temporary, expected side effects that are part of the normal healing process.
Common post-procedure effects include bruising and temporary tenderness at the injection sites, typically resolving within a few days. Patients may also notice the treated vein becoming firm or lumpy as it clots and begins absorption, which indicates the treatment is working.
Skin discoloration, known as hyperpigmentation, is a frequent side effect, appearing as brownish staining over the treated area. This occurs when blood products leak into the surrounding tissue. While it can take months or years to fade, it is a cosmetic issue, not a medical danger. A rarer, temporary side effect is telangiectatic matting, a fine network of tiny new blood vessels near the injection site, usually fading within a year.
Serious Potential Complications
Serious complications arise if the foam enters the deep venous system or the systemic circulation. One risk is Deep Vein Thrombosis (DVT), a blood clot forming in a deep vein, affecting approximately 1% to 3% of patients. If this clot breaks loose and travels to the lungs, it can cause a life-threatening Pulmonary Embolism (PE).
Neurological symptoms are also a concern, as the gas component of the foam can sometimes pass into the arterial system. These complications are usually transient and may include temporary visual disturbances, headaches, migraines, or dizziness. In extremely rare instances, the passage of microbubbles can lead to Transient Ischemic Attacks (TIAs) or stroke, with the risk estimated to be around 0.01%.
Allergic reactions to the sclerosant solution are possible, ranging from mild local reactions to systemic anaphylaxis, though this is rare. Tissue necrosis, or skin ulceration, is another uncommon complication if the sclerosant inadvertently damages nearby small arteries or leaks outside the vein.
Patient Risk Factors and Contraindications
Certain pre-existing conditions can significantly increase the risk of complications, making FST an inappropriate choice. An absolute contraindication is a known allergy to the specific sclerosant, carrying the risk of a severe allergic reaction. Patients with an acute DVT or Pulmonary Embolism should never undergo the procedure, as it could exacerbate the existing thrombotic risk.
The presence of an uncorrected Patent Foramen Ovale (PFO), a small opening between the upper chambers of the heart, majorly increases the risk of neurological complications. This opening allows gas microbubbles to bypass the lungs, where they are normally filtered, and enter the arterial circulation, potentially traveling to the brain.
Pregnancy, breastfeeding, and long-lasting immobility or confinement to bed are also considered relative contraindications, as they increase the baseline risk of blood clots.
Minimizing Risks During Treatment and Recovery
The risks associated with FST can be significantly mitigated through meticulous technique during the procedure and strict adherence to post-treatment instructions. Practitioners minimize procedural risk by using ultrasound guidance. This allows for precise needle placement and confirms the foam is contained within the target vein, reducing the chance of accidental arterial injection or foam migration. Clinicians also limit the total volume of foam injected, as excessive amounts are linked to a higher risk of thrombotic complications.
Patient compliance with post-procedure care is equally important for a safe recovery. Patients are instructed to wear compression stockings for a specified period, which helps keep the treated veins closed and reduces swelling.
Immediate and frequent ambulation, such as 30-minute walks twice daily, is encouraged to promote healthy blood flow and reduce the risk of DVT. Patients must also avoid strenuous exercise, hot baths, saunas, and air travel for a short period, as these activities can dilate superficial veins and interfere with the successful closure of the treated vessel.