Endoscopic and ultrasonographic observation of the canine prostate after transurethral balloon laser therapy (PROSTALASE).

We investigated the healing process and changes in the canine prostate after transurethral balloon-equipped laser (PROSTALASE) prostatectomy using both endoscopy and transrectal ultrasonography (TRUS). On TRUS, the prostate volume was significantly increased (123%) just after irradiation, decreasing to 106% at 1 week. Cavity formation was observed in the prostate 1 week after irradiation, and the median volume was 1.5 cm3 at 4 weeks. A TRUS study performed immediately after irradiation revealed a 1- to 2-mm deep hyperechoic lesion around the urethra. Urethrocystoscopy disclosed red and markedly edematous mucosa of the prostatic urethra, but no hemorrhage. The hyperechoic mass was also observed in the cavity on TRUS images 1 week later. Urethrocystoscopy disclosed abundant necrotic tissue within the cavity, and reddish granulomatous sections were observed on a portion of the cavity surface. At 4 weeks, the hyperechoic mass in the cavity was no longer observed on TRUS images. The prostate parenchyma was thin but uniformly isoechoic. At urethrocystoscopy, a smooth surface without redness and with the small craters, which were histologically identified as the duct openings of the prostate gland, were observed.