Answer
Foam displaces blood and keeps the sclerosant in contact with the vein wall, allowing suitable veins to be treated under specialist control.
Sources for this answer
- Aethoxysklerol 20 mg/ml solution for injection — Current selected SmPCemc · Summary of Product Characteristics
- NHSNHS · NHS medicine guidance
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.