Electrosurgical instrument and system

An electrosurgical system including an electrosurgical instrument and an electrosurgical generator, the electrosurgical instrument comprising:

• a body portion,
• an actuator mechanism associated with the body portion, and
• first and second jaw members each having a jaw body,
• the first jaw member including a first electrode having a relatively large area conductive seal surface and a relatively smaller area conductive edge portion,
• the second jaw member including a second electrode also having a relatively large area conductive seal surface and a relatively smaller area conductive edge portion,
• the first jaw member comprising:
• a third electrode associated with its jaw body, and having a conductive exposed surface area, and an insulator separating the first electrode from the third electrode,
• the actuator mechanism being configured to provide an operation of moving one or both of the first and second jaw members between a first position in which the jaw members are open, a second position in which the first and second jaw members are sufficiently closed so as to be capable of grasping tissue therebetween, and a third position in which the first and second jaw members are further closed such that the conductive seal surfaces on each jaw member are adjacent to one another such that predominantly the conductive edge portion of one or both of the seal surfaces is exposed,
• the electrosurgical generator including a source of radio frequency energy configured to produce either a coagulating RF waveform or a cutting RF waveform, and first, second and third output connections connected to the first, second and third electrodes respectively of the electrosurgical instrument,
• the generator further including a switching means, and a controller, the controller being configured such that when the jaw members of the electrosurgical instrument are in their second position with tissue grasped therebetween, the switching means directs the coagulating RF waveform between the first and second output connections and hence the first and second electrodes, and when the jaw members of the electrosurgical instrument are in their third position, the switching means directs the cutting RF waveform between one or both of the first and second electrodes and the third electrode, such that the conductive edge portions of one or both of the seal surfaces can act as a cutting electrode and the third electrode can act as a return electrode for the cutting electrode.

An electrosurgical instrument comprising:

• a body portion,
• first and second jaw members, and,
• associated with the body portion, an actuator mechanism coupled to at least one of the jaw members and configured to move that jaw member relative to the other jaw member, wherein:
• the first jaw member and the second jaw member respectively include a first electrode and a second electrode each having a respective conductive seal surface and an insulative backing, the seal surfaces facing each other so as to lie adjacent one other when the jaw members are in a closed configuration;
• the first jaw member includes a third electrode which is insulated from the first electrode by the insulative backing of the first jaw member and which is exposed when the jaw members are in their closed configuration;
• at least one of the first and second electrodes has a laterally directed conductive edge portion that remains exposed when the jaw members are in their closed configuration, the exposed surface area being relatively small compared with the area of the conductive seal surface of the at least one electrode;
• and
• the instrument also includes first, second and third connection elements allowing independent connection of the first, second and third electrodes to a radio frequency (RF) electrosurgical generator.