[Effect of electrovaporization on the prostate and its surrounding tissues]

Transurethral electrovaporization of the prostate (TVP) for benign prostatic hyperplasia (BPH) has proven to be efficacious with lower morbidity than transurethral resection of the prostate (TURP) on clinical studies. However, no histopathologic data are available to support the clinical findings in human studies. The following study was done using a canine model in an effort to evaluate these histopathologic changes.

Nine canines received antegrade electrovaporization or resection of the prostate, via an open cystoma, using Storz series resectoscope and video equipment. The dogs were sacrificed and their prostates harvested at 0 week (immediately after operation), 1 week or 5 weeks after electrovaporization or resection. The prostates were evaluated grossly as well as histologically for cavitary defects and depth of necrosis.

Prostate examination revealed superficial necrosis (less than 1.8 mm deep) at 0 week following the 270 watts operation, and less than 3 mm deep necrosis with acute inflammation and focal hemorrhage at 1 week. The depths of necrosis were less than 1.3 mm and 2.2 mm at 0 week and 1 week after the 180 W electrovaporizion. And the 120 W resection resulted in necrosis 1.1 mm and 1.6 mm deep at most, which was localized in the vaporized prostate only, with no histopathologic change in the surrounding tissues. Epithelial stratification was underway by the fifth week, but with inflammation.

TVP in the canine model showed only shallow necrosis at the site of the vaporization. These data provide a histopathologic rationale for the minimal morbidity and efficacious nature of this technique demonstrated in clinical studies.