To develop a new transperineal laser prostatectomy through a biopsy needle, we evaluated the efficacy of pulsed Ho: YAG laser irradiation for the canine prostate. The Ho: YAG laser may induce stress-wave to destroy the small vessels in the prostate. Seventeen mongrel dogs were used. After a lower midline abdominal incision, the prostate was punctured with a 18G biopsy needle in parallel to the urethra. Two prostates were punctured without the irradiation as a control. One of the 15 treated prostates was removed immediately after high fluence irradiation (500J/cm2) in left lobe and low (150J/cm2) in right lobe. In 12 of 15 dogs, each lobe of the prostate was irradiated with high fluence. In 2 of 15 dogs, each lobe of the prostate was irradiated with low fluence. The treated prostates were removed immediately, 1 week, 1 month and 2 months after the irradiation. The high fluence irradiation resulted in the sufficient volume reduction (40%) and the huge cavities were created I month later. The low fluence irradiation showed only the inflammatory reaction. The histological examination showed that the hemorrhage and subsequent histological changes may be caused by the laser induced stress-wave rather than by thermal effect. Our results suggest that transperineal irradiation with pulsed Ho: YAG laser can be useful in the treatment of prostatic obstruction.
