Distribution of current during transurethral resection.

To protect the surgeon during transurethral resection (TUR), addition of an earthing lead to the resectoscope sheath has been recommended. In vivo measurements during a prostatic TUR showed that 45% of the high-frequency current returned to earth via such a wire. In vitro tests showed bleeding to have little influence on the amount of current returning through the earthing lead. Since the current in the resectoscope sheath generates heat that may cause secondary urethral stricture, the best safeguard for both patient and surgeon against leak of current is use of an insulated sheath.