RF ablation apparatus (10) includes an anode electrode assembly (12) including an anode terminal (20) housed within a catheter (30). The catheter (30) includes a distal end wall (34) which is disposed in a plane substantially perpendicular to the longitudinal dimension of the catheter (30). The anode electrode (22) is slidably received within the cathode (30) and can be extended out beyond the distal end (32) of the catheter (30) to provide at least a first terminal for an ablation circuit. The distal end wall (34) is sized and shaped to hold a thrombus formed on the anode electrode (22) so that the anode electrode (22) can be withdrawn from within the thrombus formation and into the catheter (30), without the thrombus formation being pulled with the anode terminal (22). The outer surface of the catheter (30), or at least at the distal end (32) thereof, is made of an insulating or non-conducting material, such that a thrombus does not form over the catheter (30). The assembly allows for the generation of a thrombus to occlude a vessel (60) and without the risk of pulling any formed thrombus with the apparatus upon retrieval of the apparatus from the patient.
