BENIGN PROSTATIC HYPERPLASIA - US-GUIDED TRANSRECTAL URETHRAL ENLARGEMENT WITH RADIO-FREQUENCY - INITIAL RESULTS IN A CANINE MODEL

PURPOSE: To enlarge the prostatic urethra with thermal coagulation wit h transrectal radio-frequency (RF) application in dogs. MATERIALS AND METHODS: Eight aged dogs underwent RF ablation of periurethral prostat ic tissue forb minutes. Eighteen-gauge electrodes were placed into the periurethral tissues with a transrectal approach and ultrasound (US) guidance. Prostatic and rectal temperatures were measured during RF ap plication. US, conventional an computed tomographic (CT) retrograde ur ethrography (RUG), and CT were performed immediately (n = 8) and at 3- 96 days (n = 6) after ablation. Histopathologic analysis was performed at sacrifice immediately (n = 2), at 28 days (n = 2), or at 3 months (n = 4) after treatment. RESULTS: All procedures were successful with no complications and were performed in less than 30 minutes. Rectal mu cosal temperature did not exceed 38 degrees C. Immediately after treat ment, CT and US demonstrated 1.2-cm foci of altered periurethral tissu e that corresponded to solid coagulated tissue at histopathologic anal ysis. By day 3, CT, RUG, and US demonstrated that these foci had begun to cavitate, resulting in enlargement of the urethra. Complete cavita tion was demonstrated by day 28. Minimal reduction in the degree of ur ethral enlargement was noted by day 60, but narrowing, urethral strict ures, or fistulas were not observed at 3 months. At histopathologic an alysis, focal cavitary enlargement with at least doubling of the ureth ral diameter and with normal urothelium was noted in all dogs survivin g at least 28 days. CONCLUSION: Transrectal RF urethral enlargement is feasible and safe in animals and merits investigation for alleviating urethral obstruction due to benign prostatic hyperplasia.