Thermal and histological effects of bipolar and monopolar electrosurgical resection of the prostate in a canine model

Bipolar transurethral resection (TUR) is an alternative to monopolar TUR in the treatment of benign prostatic hyperplasia and offers the major advantage of utilizing 0.9% sodium chloride for irrigation. Claims have been made that bipolar electrosurgery in clinical use causes less thermal damage to adjacent tissues. We sought to assess tissue thermometry and histopathologic thermal effects of a bipolar system in comparison to standard monopolar TUR in an animal model. Eight male beagles were studied. A lower midline incision was used to access the prostate. Fiber-optic thermosensors were placed within the prostate. A midline cystotomy was used to perform antegrade resection of the prostate using a bipolar TUR system (VISTA CTR) with normal saline or a monopolar device using glycine. Resection of a 1cm cavity was performed in each lateral lobe. Animals were sacrificed acutely and the prostates excised for histopathological assessment of thermal damage. In both groups, prostatic temperature rises were transient and fell with increasing distance from the resection site. The greatest temperature increase occurred in the monopolar group (24.2 ±3.9°C) compared to the bipolar group (6.8 ±1.8°C, p<0.0001). The depth of thermal damage was greatest in the monopolar group (0.59 ± 0.27mm vs 0.15 ± 0.02mm in the bipolar arm, p<0.0001). Bipolar TUR generated significantly less heat and produced less histopathological thermal damage compared to monopolar prostatic resection in a canine model. The clinical benefits of these findings remain to be determined.