Patent ID: 6923803

Claim:
A method of treating a tumour in a colon using an electrosurgical system comprising: an electrosurgical generator adapted to generate a radio frequency oscillating voltage output across first and second output terminals; an electrosurgical instrument having an active tissue treatment electrode connected to the first generator output terminal; fluid delivery means for delivering electrically-conductive fluid to the tumour to be treated; and a return electrode connected to the second generator output terminal, the method comprising the steps of: enclosing, in a substantially fluid-tight manner, a space in the colon within which the tumour to be treated is located, and within which at least the active electrode is located; operating the fluid delivery means at least partly to fill the space with electrically-conductive fluid; operating the generator to apply a radio frequency voltage between the active and return electrodes, and completing at least a part of a conduction path between the active and return electrodes using the electrically-conductive fluid; and manipulating the active electrode in the vicinity of the tumour to be treated; wherein the space is enclosed by means of a flexible enclosing member which forms a seal with a portion of the colon.