AN ELECTROSURGICAL INSTRUMENT

摘要

In an electrosurgical instrument for the treatment of tissue in the presence of an electrically conductive fluid medium (e.g. "underwater surgery") a bipolar electrode assembly has an active electrode having an exposed tissue treatment portion (34A), a return electrode (38) having an exposed fluid contact surface, and an insulating member (36) positioned between and electrically insulating the active electrode in the return electrode. The insulating member serves to space apart the exposed active electrode treatment portion and the exposed fluid contact portion of the return electrode. The dimensions and configurations of the exposed portions of the electrodes and of the insulating member are such that when the electrode assembly is immersed in a conductive fluid medium, the ratio between the longest and shortest conduction path lenghts between the active and return (b:a) electrodes is less than or equal to 2:1. The invention also includes a combination of an electrosurgical instrument and a radio frequency generator.