This is a non-interventional PASS to define the incidence and risk factors for procedure-related neurological AE in patients having Fibrovein ultrasound guided foam sclerotherapy (UGFS) for varicose veins (VV)incorporating a drug utilisation study. The research questions are: 1. What are the incidence, type, severity, duration, treatment (where required), and outcome of procedure-related neurological AE in patients undergoing UGFS for lower limb VV using Fibrovein? 2. To what extent, if any, are these procedure-related neurological AE associated with identifiable patient and treatment characteristics? 3. Post-marketing authorisation (PMA), how is UGFS with Fibrovein being used in the “real world” to treat lower limb VVs (nested drug utilisation study)? The population to be studied comprises adult, non-pregnant, non-breast-feeding, patients undergoing UGFS with Fibrovein for VV. Patient and treatment variables will be collected on Proforma 1. These will include age, gender, BMI, primary versus recurrent, deep venous disease and/or DVT, CEAP grade, type of VV, history of migraine / TIA / stroke / diabetes / high BP, smoking status, known PFO, previous Fibrovein UGFS, unilateral vs. bilateral treatment, method of foam preparation, Fibrovein volume concentration and gas ratio, gas used, number of injections, concomitant treatments, compression regime and duration. Co-investigators will contact the UK Co-ordinating Centre should a SAE occur at the time of treatment or subsequently (details recorded on Proforma 2). Data will be recorded for 10,000 treatments. Non-patient-identifiable data will be entered to a password-protected computerised database. Descriptive and summary statistics will be used. If the incidence of neurological AE is 0.35%, 10,000 will provide an 80% chance (power) of showing that rate is significantly below 0.5% at the 5% significance level. Patients will be treated according to contemporary “standards of care” at each participating centr