A previous in vitro study demonstrated that 180W was the optimal power to reduce photoselective vaporization of the
prostate (PVP) time for larger prostate glands. In this study, we investigated anatomic and histologic outcomes and
ablation parameters of 180W laser performed with a new 750-μm side-firing fiber in a survival study of living canines.
Eight male canines underwent anterograde PVP with the 180W 532-nm laser. Four each animals were euthanized 3
hours or 8 weeks postoperatively. Prostates were measured and histologically analyzed after hematoxylin and eosin
(H&E), triphenyltetrazolium chloride (TTC), or Gomori trichrome (GT) staining. Compared to the previous 120W laser,
PVP with the 180W laser bloodlessly created a 76% larger cavity (mean 11.8 vs. 6.7 cm3; p=0.014) and ablated tissue at
a 77% higher rate (mean 2.3 vs. 1.3 cm3/min; p=0.03) while H&E- and TTC-staining demonstrated its 33% thicker mean
coagulation zone (2.0±0.4 vs. 1.5±0.3 mm). H&E-stained cross-sectional prostatic tissue specimens from the 3-hour
(acute) group showed histologic evolution of concentric non-viable coagulation zone, partially viable hyperemic
transition zone of repair, and viable non-treated zone. H&E- and GT-stained specimens from the 8-week (chronic) group
revealed healed circumferentially epithelialized, non-edematous, prostatic urethral channels with no increase in collagen
in the subjacent prostatic tissue vis-á-vis the normal control. Our canine study demonstrates that 180W 532-nm laser
PVP with its new fiber has a significantly higher ablation rate with a more hemostatic coagulation zone, but equally
favorable tissue interaction and healing, compared with our previous 120W canine study.