What are sclerosing agents?
Sclerotherapy is a medical procedure used to treat spider veins and varicose veins by injecting a solution directly into the vein. This solution, known as a sclerosant, irritates the inner lining of the blood vessel (the endothelium), causing it to scar and collapse. The vein is then reabsorbed by the body, and blood is rerouted through healthier veins. The type of sclerosant used can vary based on factors such as the size and location of the vein being treated. The agents are categorized into different classes based on their chemical properties and mechanism of action.
The main types of liquid used in sclerotherapy
Detergent Sclerosants
Detergent sclerosants are a popular category of sclerosing agents that work by damaging the cell membranes of the endothelium. This process, known as protein denaturation, triggers a cascade of events leading to inflammation, localized clotting, and eventual fibrosis of the vessel. They can be prepared as either a liquid or a foam. Examples include:
- Polidocanol (Asclera®, Varithena®): This synthetic fatty alcohol is widely used for treating spider and reticular veins, and in foam form, larger varicose veins. It is known for having less pain and a lower risk of allergic reaction compared to other agents. The FDA has approved polidocanol for sclerotherapy in the United States.
- Sodium Tetradecyl Sulfate (STS) (Sotradecol®): An FDA-approved synthetic organic sodium salt, STS is a potent detergent sclerosant. It is effective for various vein sizes but carries a higher risk of side effects like allergic reactions, tissue necrosis if extravasated, and hyperpigmentation.
Osmotic Sclerosants
Osmotic sclerosants work by causing chemical dehydration of the cells in the vein wall, which also leads to irritation and collapse. These agents are generally less potent than detergents and are often used for smaller, superficial veins.
- Hypertonic Saline: A concentrated salt solution (often 23.4% sodium chloride) is a very old and effective sclerosant. Its primary advantage is that it is a naturally occurring bodily material, making allergic reactions highly unlikely. However, it is often associated with discomfort, such as stinging, cramping, and a higher risk of hyperpigmentation. It is typically reserved for small veins.
- Glycerin (Glycerol): A colorless, viscous liquid, glycerin is used for treating very small-diameter spider veins, especially for cosmetic purposes. It is known for causing fewer side effects like hyperpigmentation and ulceration compared to other agents.
Other Sclerosants
Other agents, though less common, are also used depending on the specific application.
- Sodium Morrhuate: A fatty acid derived from cod liver oil, it was one of the first sclerosants used. Due to potential allergic reactions and other side effects, it has largely been replaced by newer agents.
Liquid vs. Foam Sclerotherapy
The method of sclerosant delivery can significantly impact the outcome, particularly for larger veins. While liquid sclerosants have been used for decades, the development of foam sclerotherapy has revolutionized treatment for larger vessels.
- Liquid Sclerosants: These are the traditional form, primarily used for small, surface-level veins (spider veins). The solution mixes with and is diluted by the blood within the vein, potentially limiting its effectiveness in larger vessels.
- Foam Sclerosants: A sclerosant mixed with a gas (like air or carbon dioxide) immediately before injection creates a foam, similar in texture to shaving cream. The foam displaces blood, allowing for more prolonged and concentrated contact with the vein wall. This makes it more effective for treating larger varicose veins, often with fewer treatment sessions needed. Foam sclerotherapy, especially when guided by ultrasound (UGS), allows for treatment of deeper, larger veins. One example is Varithena®, a proprietary, ready-made polidocanol microfoam.
Comparison of common sclerosing agents
| Feature | Polidocanol (Asclera®) | Sodium Tetradecyl Sulfate (STS) | Hypertonic Saline | Glycerin |
|---|---|---|---|---|
| Mechanism | Detergent (damages endothelium) | Detergent (damages endothelium) | Osmotic (dehydrates cells) | Osmotic (dehydrates cells) |
| Best for | Spider, reticular, and larger varicose veins (in foam) | Small to medium-sized varicose veins | Very small, superficial spider veins (<1mm) | Small spider veins (0.2-0.4mm) |
| Pain Level | Generally low, minimal discomfort reported | Moderate, injection site reactions common | Mild to moderate stinging or cramping | Generally low, very comfortable |
| Hyperpigmentation Risk | Low to moderate | Moderate to high, can be long-lasting | Moderate to high, can be permanent | Very low incidence |
| Allergic Reaction | Possible but rare | Possible and potentially severe, contraindicated in asthmatics | Extremely unlikely, as it's a naturally occurring substance | Rare, good tolerability |
Conclusion: Making the right choice
There is no single best answer for what liquid is used in sclerotherapy; the ideal choice depends on the specific venous condition and patient characteristics. A vascular specialist will conduct a thorough evaluation, often using duplex ultrasound, to determine the most effective and safest sclerosant for your needs. While foam sclerosants have shown superior efficacy for larger veins, especially when guided by ultrasound, liquid agents remain a valuable tool for treating smaller, superficial vessels. For instance, a patient with small spider veins who is concerned about hyperpigmentation might be a better candidate for glycerin, while someone with larger varicose veins may benefit from a polidocanol foam treatment. Discussing your medical history and treatment goals with a qualified professional is essential for a safe and successful outcome.(https://www.theveincompany.com/asclera-for-sclerotherapy/)
Risks and considerations
While generally safe, sclerotherapy procedures carry risks depending on the sclerosant used. The most common side effects include minor bruising, itching, and temporary skin discoloration (hyperpigmentation). More serious, albeit rare, complications can include allergic reactions, deep vein thrombosis (DVT), tissue necrosis, and neurological events. Your doctor will discuss these potential risks based on the chosen sclerosant and your overall health.
The procedure and recovery
During the procedure, the doctor injects the sclerosant using a fine needle. The process is typically quick and does not require anesthesia. After the injection, the treated area is compressed with stockings to promote vein collapse and reduce the risk of clot formation. Patients can usually resume normal daily activities immediately, though strenuous exercise may be restricted temporarily. Most patients require several sessions to achieve the desired results, with treatments typically spaced several weeks apart.
