Used to assess valvular competence of saphenous and communicating veins in legs; performed by elevating patientÕs leg to drain blood from venous system and then occluding greater saphenous system (but not femoral system) with tourniquet. Rapid filling is indication of incompetency of valves in communicating system. Sudden filling of superficial veins after patient has stood for 20 seconds and had tourniquet removed is indication of incompetency of valves in saphenous system.