Operative Procedure: Catheter Directed Foam Sclerotherapy (CDS) Group The straight segment of axial vein will be cannulated under local anaesthesia at the lowest point of demonstrable reflux and a guide-wire inserted to facilitate the placement of the catheter system. The access cannulae will be removed and replaced with a 5F introducer sheath over a guide. A Unifuse® (AngioDynamics, Cambridge, UK) catheter system will be deployed via the sheath.