Hyperbaric oxygen therapy attenuates urethral stricture formation after urethral injury: an experimental rabbit study

Abstract

Purpose Urethral stricture (US) is a frequent and challenging urological entity characterized by spongiofibrosis and luminal narrowing, often leading to recurrent infections, urinary retention, and upper tract deterioration. Despite various endoscopic and open surgical options, high recurrence rates remain a major problem, and there is no established medical therapy to prevent stricture formation. To investigate the protective effect of hyperbaric oxygen (HBO) therapy on fibrosis and stricture formation in an experimental urethral injury model in rabbits using objective endoscopic, radiologic, and histopathologic parameters. Methods Twenty-eight male New Zealand rabbits were randomized into three groups: sham (n = 8), urethral injury without treatment (control, n = 10), and urethral injury plus HBO (HBO, n = 10). Among the 20 rabbits with urethral injury, allocation to the untreated control group (Group 2) and the HBO treatment group (Group 3) was performed in a 1:1 ratio using a computer-generated randomization list. Standardized circumferential electrocoagulation was applied to the bulbar urethra in the control and HBO groups. HBO was administered at 2 ATA, 90 min/day for 21 consecutive days starting on the day of injury. On day 28, all animals underwent urethroscopy and retrograde urethrography; urethral specimens were then harvested for histopathological evaluation. Fibrosis was graded (0-3) using Masson trichrome staining. Results Normal urethral diameters were similar among the groups (p = 0.604). Median stricture diameter was significantly lower in the untreated control group compared with the HBO and sham groups (2.15 mm vs. 8.05 mm and normal segment, respectively; p < 0.001). Median percentage urethral narrowing was 78.52% in the control group and 23.51% in the HBO group (p < 0.001). Fibrosis scores were significantly higher in the control group than in the HBO and sham groups (p < 0.001). Conclusion HBO therapy significantly attenuated fibrosis and urethral narrowing in this experimental urethral injury model. These findings suggest that HBO may represent a promising adjuvant strategy to prevent US formation after urethral trauma, warranting further clinical investigation.