THRomboprophylaxis in Individuals Undergoing Superficial endoVEnous Treatment (THRIVE)

Endovenous interventions are keyhole operations for varicose veins that are carried out from within the vein itself. Varicose veins are enlarged veins close to the surface of the skin. They are connected to the bigger deeper veins in the leg (known as deep veins). Because of this, operations to close the varicose veins can increase the chance of a blood clot forming in the deep veins. Blood clots in the deep veins happen in around 1 in 50 people after endovenous operations. A clot in the leg can cause swelling, pain, and other long-term problems. If a clot in the leg breaks off and travels to the lungs, it can cause problems with the lung' ability to move oxygen from the air into the blood and may, in rare cases, be life threatening. Varicose vein procedures may carry a slightly higher risk of blood clot formation, and we are currently unsure if current clot reducing medicines are beneficial in preventing blood clots in people having varicose vein procedures. This study will investigate if it is worthwhile prescribing medicines to reduce blood clots after varicose vein procedures.

Inclusion Criteria: * Adults (\>18 years) * Scheduled to undergo endovenous intervention of truncal varicose veins under local anaesthesia * Treatment technologies including radiofrequency, laser, mechanochemical, foam sclerotherapy and cyanoacrylate glue Exclusion Criteria: * Clinical indication for therapeutic anticoagulation e.g., atrial fibrillation * Previous personal or first-degree relative history of VTE * Thrombophilia * Female patients of childbearing potential who have a positive pregnancy test * A history of allergy to heparins or direct oral anticoagulants * A history of heparin-induced thrombocytopenia * Inherited and acquired bleeding disorders * Evidence of active bleeding * Concomitant major health problems such as active cancer and chronic renal and/or liver impairment * Known thrombocytopenia (platelets known to be less than 50 x 109 /l) * Surgery or major trauma in the previous 90 days * Recent ischemic stroke in the previous 90 days * Inability to provide consent