The present invention relates to devices for resecting an organ in a cavity of a living body, in particular of a human being. The device according to the invention is essentially characterized in that it comprises a guide (10) composed of at least a tube (21) and a tube (22), both of them cylindrical, the tube (22) being mounted in the first tube (21)； at least one electrical conductor surrounded by a sheath (33, 34) made of an electrically insulating material, the tube (21) being a cylinder of revolution with an inner radius of value R1, the tube (22) comprising a part (221) which is a cylinder of revolution with an outer radius of value R2 less than R1 and with an angle at the centre of a value Ac, and a part (222) which is not a cylinder of revolution and has an angle at the centre of value "360° - Ac"； the insulated conductor (31, 32) being mounted in contact with the part (222) of the tube (22), between the outer wall of this tube (22) and the inner wall of the tube (21)； and means (40) for keeping this insulated conductor (31, 32) in contact with the part (222) of the tube (22).
