Factors affecting size and configuration of electrovaporization lesions in the prostate

Objectives. Transurethral electrovaporization of the prostate is a new, minimally invasive technique being used by urologists for surgical ablation of prostatic tissue. There are insufficient data concerning factors affecting the vaporization and coagulation lesions produced by this technique. The aim of this study was to determine the role of various parameters for adequate tissue evaporation. Methods. This study compared bovine liver and human prostatic lesions made by the Vaportrode instrument with those produced by standard electrocautery loops, roller balls, and laser fibers. Additionally, two electrosurgical instruments with differing technical capabilities were compared for their ability to cause vaporization of tissue. Results. Results revealed that the Vaportrode lesions were maximal with a new electrode when used with a Force 40S electrosurgical generator set at 300 W and a drag speed of 25 to 30 seconds per 10 mm of tissue. The lesions produced by this technique had a 74% greater coagulation volume compared to a standard cautery loop. The evaporation defect was comparable to a laser lesion produced in contact at 60 W. Conclusions. We conclude that electrovaporization under optimal conditions causes a vaporization lesion comparable to that produced by high power density laser prostatectomy. Additionally, the coagulation volume of a vaportrode lesion is considerably greater than that produced by standard electrocautery resection.