According to one aspect, a medical system may include an instrument including an end effector for acting as a monopolar electrode. The end effector may be configured to be positioned in a body of a subject and emit radiofrequency energy towards a target area in the body. The medical system may further include a return electrode. The return electrode may be deliverable within the body proximate the target area and separately from the instrument and the monopolar electrode. The return electrode may be configured to contact tissue in the body proximate the target area and receive radiofrequency energy emitted from the end effector.