Análise histomorfométrica do músculo bulboesponjoso em pacientes com estenose de uretra bulbar

Abstract

Background: Bulbospongiosus muscle (BSM) covers the bulbar urethra and its function is to expel of seminal fluid and urine from the urethra. Bulbar urethroplasty can evolve with ejaculatory dysfunction and post-mictional dribbling, which has led to the preservation of this muscle during the surgical procedure. Objective: To characterize the BSM in patients with bulbar urethral strictures. Methods: We studied 21 patients divided into 2 groups: Stricture Group (n=14; mean age=62.00 years) with bulbar stricture submitted to open urethroplasty; and Control Group (n=7; mean age=60.14 years) with penile strictures (hypospadias cripples, penile cancer and/or penile infection) who were submitted to perineal urethrostomy. Samples of the BSM were dissected and histologic sections were stained by histochemical and immunohistochemical techniques. Histomorphometric analyzes were performed on photomicrographs. Means were statistically compared using the unpaired Student t test and the Mann-Whitney test (P<0.05). Results: The etiology of bulbar urethral stricture was idiopathic in 2 cases (14.29%), post-transurethral resection of the prostate in 6 (42.86%), post open radical prostatectomy in 5 (35.71%) and post open prostatectomy in 1 case (7.14%). The average length of the stricture was 2.08 cm. The only parameter analyzed with significant difference between the groups was the vessels (significant difference between the control group: 5.11±1.98% and stricture group: 3.57±1.32%, P=0.0460). The quantitative analysis of the collagen fibers (Control Group: 10.63±5.37% and Stricture Group: 10.83±4.55%, P=0.9296); diameter of BSM muscle fibers (Control Group: 41.71±14.63 µm and Stricture Group: 40.11±8.59 µm, P=0.76 and elastic system fibers (Control Group: 3.83±1.54% and Stricture Group: 5.43±2.90%, P=0.2601) showed no significant difference. Conclusions: Histologic analysis showed a significant decrease of the BSM vessels in urethral stricture, without changes in elastic system fibers, collagen, nerves, and muscle fiber diameter. These findings show that the bulbar urethral stricture causes minimal alterations in the structure of the BSM