What is foam sclerotherapy?
Foam sclerotherapy is a minimally invasive medical procedure used to treat varicose veins and smaller ‘spider veins’ by injecting a chemical foam directly into the damaged vessels. In the UK, it is a key treatment option recommended by NICE, particularly for veins that are too twisted or small for laser treatment. The foam displaces the blood in the vein and irritates the lining, causing the vessel to scar, collapse, and eventually be absorbed by the body. Unlike traditional surgery, this procedure is performed in an outpatient setting without the need for general anaesthesia.
What We will cover in this Article
- The chemical mechanism of sclerosant foam
- Step-by-step walkthrough of ultrasound-guided sclerotherapy
- Comparative success rates and clinical data
- Common causes of veins requiring foam treatment
- Lifestyle and medical triggers for the procedure
- Differentiating foam from liquid sclerotherapy
- Safety protocols and managing post-procedure discolouration
Key Data: Foam Sclerotherapy Performance Metrics
The following table provides a snapshot of the clinical expectations and outcomes associated with this procedure.
| Metric | Foam Sclerotherapy Data |
| Initial Closure Rate | 80% – 90% (after first session) |
| Procedure Time | 20 – 30 minutes |
| Return to Normal Activity | Immediate (with compression) |
| Number of Sessions | Often 1–3 per leg |
| Common Side Effect | Temporary ‘staining’ or pigmentation (~20% of cases) |
How the procedure works
Foam sclerotherapy begins with a specialist mixing a liquid sclerosant (usually sodium tetradecyl sulfate or polidocanol) with a small amount of air or another gas to create a consistency similar to shaving foam. This foam is significantly more effective than liquid because it does not mix with blood; instead, it pushes the blood aside, ensuring the chemical remains in full contact with the vein wall.
Under ultrasound guidance, a clinician identifies the precise entry point. A fine needle is inserted, and the foam is injected. You may see the foam moving through the veins on the ultrasound monitor as it causes the vein to spasm and shut. Because the foam is highly visible on ultrasound, the clinician can track its movement to ensure it stays within the target area and does not enter the deep vein system.
Differentiating Liquid and Foam Sclerotherapy
While both use similar chemicals, the application and target veins differ significantly.
| Feature | Liquid Sclerotherapy | Foam Sclerotherapy |
| Target Vein | Small spider veins / thread veins | Larger varicose and ‘trunk’ veins |
| Visibility | Hard to see on ultrasound | Highly visible on ultrasound |
| Effectiveness | Diluted by blood in larger veins | Displaces blood for maximum impact |
| Contact Time | Brief | Extended contact with the vein wall |
Causes of veins treated with foam
Foam sclerotherapy is particularly useful for treating ‘tributary’ veins the smaller branches that come off the main trunk veins or for veins that have returned after previous surgery. It is also the treatment of choice for patients whose veins are too ‘tortuous’ (winding) for a straight laser fibre to pass through.
Common causes for these veins include:
- Recurrent Varicose Veins: Veins that reform or reopen years after a traditional stripping operation.
- Complex Anatomy: Naturally twisted vein structures that are difficult to navigate.
- Chronic Venous Reflux: Persistent backward flow of blood that puts pressure on surface veins.
Triggers for foam treatment
Patients are often triggered for foam sclerotherapy when they develop complications that make conservative management (like stockings) insufficient. It is frequently used as a secondary treatment alongside laser ablation to ‘tidy up’ any remaining visible veins.
Triggers that suggest foam treatment is appropriate:
- Residual Veins: Visible bulging veins remaining after a primary laser or RFA procedure.
- Symptomatic Small Veins: Smaller veins that are causing localised burning or aching.
- Skin Vulnerability: Areas where the skin is becoming thin or fragile due to underlying vein pressure.
Post-procedure recovery and safety
Recovery is very rapid. You will be asked to walk for 15 to 20 minutes immediately following the injections to ensure the foam is cleared from the deep veins. You must wear clinical-grade compression stockings, usually for one to two weeks, to keep the treated veins compressed while they scar over.
Safety considerations:
- Skin Staining: Some patients develop a brown line over the treated vein (haemosiderin staining). This is not permanent but can take 6 to 12 months to fade.
- Lumps and Tenderness: It is normal to feel ‘firm’ lumps where the veins have closed. These are not new clots but are a sign the treatment is working.
- Visual Disturbances: A very rare, temporary side effect where some patients see ‘sparkles’ or blurred vision for a few minutes after the injection.
Conclusion
Foam sclerotherapy is a versatile and highly effective treatment that fills a vital gap in modern vein care. By using a specialized foam to target veins that are otherwise difficult to treat, it provides a minimally invasive alternative to traditional surgery. With a high success rate and the convenience of being an outpatient procedure, it remains a cornerstone of vascular management in the UK.
If you experience severe, sudden, or worsening symptoms, such as significant chest pain or sudden shortness of breath after the procedure, call 999 immediately.
Does the foam travel to my heart?
The foam is used in small, controlled amounts. As soon as it reaches the larger, deep veins where blood is moving quickly, it is diluted and safely neutralised by the body.
Will I need more than one treatment?
Many patients require two or three sessions to achieve the best results, especially if they have many branching varicose veins.
Is the procedure painful?
The injections feel like small pin-pricks. You may feel a slight stinging or ‘cramping’ sensation as the foam causes the vein to spasm, but this lasts only a few seconds.
When can I see the results?
The veins may look worse before they look better. It can take several weeks for the inflammation to go down and several months for the veins to fully disappear.
Can I fly after foam sclerotherapy?
Most specialists recommend waiting at least two weeks before taking a long-haul flight to reduce the risk of deep vein thrombosis (DVT).
What happens if the vein reopens?
If a vein reopens, the procedure can safely be repeated, or an alternative method can be discussed with your specialist.
Can I exercise after the treatment?
You should avoid high-impact exercise for about a week, but gentle walking is highly encouraged from day one.
Authority Snapshot
This article outlines the clinical application of foam sclerotherapy according to the guidelines set by the National Institute for Health and Care Excellence (NICE) and the British Society of Interventional Radiology. The data provided reflects current UK best practices for non-surgical vein closure. This information is intended to help patients understand the technical and practical aspects of their treatment. Dr. Rebecca Fernandez is a UK-trained physician with an MBBS and experience in general surgery, cardiology, internal medicine, gynecology, intensive care, and emergency medicine. She has managed critically ill patients, stabilised acute trauma cases, and provided comprehensive inpatient and outpatient care. In psychiatry, Dr. Fernandez has worked with psychotic, mood, anxiety, and substance use disorders, applying evidence-based approaches such as CBT, ACT, and mindfulness-based therapies. Her skills span patient assessment, treatment planning, and the integration of digital health solutions to support mental well-being.
