Electrical burn of urethra as cause of stricture after transurethral resection

Background and Purpose: One of the most common complications of transurethr al resection is urethral stricture. The exact etiology is still controversi al. Postulated pathophysiology ranges from mechanical trauma to the urethra during the resection to inflammatory reaction secondary to local anesthesi a. We propose electrical burn to the urethra as a contributory factor in so me cases, Materials and Methods: Electrical events during transurethral resection wer e simulated in vitro, The distribution of current was measured at the loop/ rollerball and in the outer metal sheath. Both an intact loop/rollerball an d loop/rollerball with faulty insulation were tested, Various power outputs simulating coagulation, cutting, and vaporization were used. Data were rec orded both in settings where the outer metal sheath was and was not smeared with nonconductive lubricating gel. Results: Approximately 20% of the total current output was shunted to the m etal sheath when an intact loop/rollerball was used, One hundred percent of the current was short-circuited to the sheath when a loop/rollerball with faulty insulation was retracted into the sheath. Little current was detecta ble in the nonconductive lubricating gel, We then calculated the length of time required, in various settings, to reach tissue temperature of 45 degre es C, when protein denaturation starts. The higher the power output and the smaller the contacting surface area, the more likely it is for urethral bu rns to occur. Conclusion: Our in vitro experiment showed that urethral burns secondary to stray current in the resectoscope sheath are unlikely when an intact loop is used. However, urethral burns can occur when a loop/rollerball with faul ty insulation is used, especially in combination with nonconductive gel tha t is dispersed unevenly within the urethra.