Hazards of electrocautery with an ungrounded endoscope

Current leaking onto the endoscope from a unipolar instrument can flow through the endoscopist, producing burns to the eyes (A) and hands (B). A burn to the patient (C) can result if tissue contacts exposed metal on the endoscope. The use of a grounded safety cord provides a direct, low resistance pathway for current to return to the generator, thus avoiding the undesired pathways indicated by the broken lines.