Electrosurgical instrument with a suction lumen and at least one electrode having a plurality of apertures

An electrosurgical instrument comprises an instrument shaft 14 having a longitudinal axis and a suction lumen (Figure 3, 24) that extends at least partially along the instrument shaft. An electrode assembly is located at one end of the shaft. The electrode assembly comprises at least one tissue treatment electrode, the tissue treatment electrode having a distal end face 17 and at least one side face 18. The tissue treatment electrode includes a plurality of apertures 19, 20 in communication with the suction lumen, at least one aperture 19 being present in the end face 17 and at least one aperture 20 being present in the side face 18. In one embodiment the distal end face 17 has at least a transverse portion oriented at a 90 degree angle to the longitudinal axis and the at least one side 18 face has at least a radial portion offset but parallel to the longitudinal axis. In another embodiment the electrode assembly comprises a cupola shaped tissue treatment electrode. The instrument allows suction or aspiration to be applied through the apertures 19, 20.