Thermal cautery is often confused with electrosurgery. In electrosurgery, a
high frequency current flows from the electrosurgical unit through a small
active electrode applied to the tissue, and back to the electrosurgical unit
through a second, larger return electrode. The electrosurgical heating effect
that causes tissue destruction is produced by the electrical resistance of
tissue to the high-frequency current.
With thermal cautery, however, no current flows through the patient. The tip
of the cautery instrument becomes heated by the passage of an electric current
through a high resistance wire. The heat transferred from the tip by conduction
coagulates the tissue.
