Uterine manipulator with neutral return electrode

1 . A method of determining an in-situ position of a vaginally-insertable uterine device, the method comprising:

using an electrosurgical generator, issuing a drive signal to a first return electrode, wherein the uterine device comprises a colpotomy cup comprising an outer wall portion, a base, and a protrusion configured for receiving an elongate shaft and the first return electrode is arranged on the protrusion;

using the electrosurgical generator, receiving a portion of the issued drive signal from a second return electrode arranged on the protrusion;

using a processor of the electrosurgical generator, monitoring an electrical property between the first and second return electrodes based on the issued drive signal and the received portion of the issued drive signal to determine if a threshold has been traversed; and

based at least in part on the threshold being traversed, using a processor to permit issuance of a second signal to an active electrode.

2 . The method of claim 1 , wherein based at least in part on the monitored electrical property traversing the threshold, issuing an indication signal to a user interface to indicate that the uterine device is in a treatment position.

3 . The method of claim 1 , wherein the first return electrode is located distal of the second return electrode along the elongate shaft of the uterine device.

4 . The method of claim 3 , wherein monitoring the electrical property includes monitoring an impedance between the first return electrode and the second return electrode.

5 . The method of claim 3 , wherein monitoring the electrical property includes monitoring voltage, current, and phase.

6 . The method of claim 3 , further comprising inserting the elongate shaft into a patient's cervix and uterus prior to issuing the drive signal.

7 . The method of claim 3 , wherein the first return electrode and the second return electrode extend circumferentially around the elongate shaft.

8 . The method of claim 3 , wherein the first return electrode has a first surface area and the second return electrode has a second surface area.

9 . The method of claim 8 , wherein the first surface area is larger than the second surface area.

10 . The method of claim 9 , wherein the first surface area is from 20% to 200% larger than the second surface area.

11 . The method of claim 10 , wherein the first surface area is from 50% to 150% larger than the second surface area.

12 . The method of claim 3 , wherein the first return electrode has a first longitudinal length and the second return electrode has a second longitudinal length.

13 . The method of claim 12 , wherein the first longitudinal length is greater than the second longitudinal length.

14 . The method of claim 3 , wherein issuing the drive signal comprises delivering a monitoring signal at a predetermined clock frequency to establish resonations.

15 . The method of claim 14 , further comprising producing a voltage indicative of the resonations.

16 . The method of claim 15 , further comprising monitoring changes in an amplitude of the resonations.

17 . The method of claim 16 , further comprising determining a magnitude of impedance between the first return electrode and the second return electrode based on the changes in the amplitude.

18 . The method of claim 1 , wherein the second signal comprises therapeutic energy being delivered to the active electrode.

19 . A method of determining an in-situ position of a vaginally-insertable uterine device, the method comprising:

inserting the uterine device into the vagina of a patient;

advancing the uterine device to the cervix and arranging a first return electrode of the uterine device and a second return electrode of the uterine device within the cervix;

using an electrosurgical generator, issuing a first signal to the first return electrode;

using the electrosurgical generator, receiving a portion of the issued first signal from the second return electrode;

using a processor of the electrosurgical generator, monitoring an electrical property of the first and second return electrodes based on the issued first signal and the received portion of the issued first signal to determine if a threshold has been traversed to confirm that the first and second return electrodes are in contact with an inner surface of the cervix; and

based at least in part on the threshold being traversed, using a processor to permit issuance of a second signal to an active electrode.