This is an abbreviation for Superficial Vein Thrombosis. It encompasses thrombosis of superficial veins, like varicose veins, as well as thrombosis of intermediate veins like the saphenous veins. Apart from causing leg swelling or the inconvenience of a localised phlebitis, the significance of SVT is that it may be associated with a concurrent unsuspected DVT. Patients with SVT should be screened for a DVT using duplex ultrasound. Prophylactic anticoagulation is advised and graduated elastic compression stockings should be worn. The risk of DVT is reduced if patients have varicose veins. The risk is increased if there is a saphenous thrombosis without concurrent varicose veins. A blood test screen for inherited hypercoagulability may be considered in these circumstances.