Holmium:YAG Laser-Assisted Induction of Bladder Neck Contracture in a Rat Model

Bladder neck contracture (BNC) is a fibrotic narrowing of the bladder outlet and a challenging complication after transurethral resection of the prostate (TURP). Existing animal models often rely on extravesical ligation or chemical cauterization, which do not adequately reproduce the thermal injury-driven fibrosis that develops after endoscopic surgery and may show limited reproducibility. Here, we describe a rat model of bladder neck fibrosis induced by transvesical Holmium:YAG laser (Ho:YAG laser) ablation of the bladder neck. After a small lower midline laparotomy and cystotomy, a 200-µm Ho:YAG laser fiber is introduced into the bladder lumen under direct visualization. Laser energy is delivered in contact mode at 1.0 J and 10 Hz for 5 s per point at the 3 and 9 o'clock positions of the bladder neck, corresponding to 50 J per point and 100 J per animal. Four weeks later, treated animals develop gross bladder enlargement, bladder neck narrowing, bladder wall thickening, and histological evidence of fibrotic remodeling, including increased collagen deposition and increased collagen type I and III expression. This protocol provides a practical model that mimics localized thermal injury-induced scarring at the bladder outlet. Because female rats are used and functional urodynamic testing was not performed in the current study, the model is best suited for studying bladder neck fibrosis and structural remodeling rather than fully reproducing male post-prostatic-surgery BNC. The model may be useful for studying the fibrotic mechanisms of BNC and for preclinical evaluation of anti-fibrotic or reconstructive interventions.