Expression and importance of relaxin in vaginal wall tissues from women with pelvic organ prolapse and with/without stress urinary incontinence

Abstract

Background and aim: Thousands of women worldwide suffer from pelvic organ prolapse and stress urinary incontinence. Low quality of pelvic connective tissue contributes to the development of the above conditions. Previous studies suggest that relaxin reduces the tensile strength of pelvic connective tissue. The aim of this study was to assess the presence of relaxin in uterine supporting tissues from patients with pelvic organ prolapse and stress urinary continence. Methods: We recruited 90 women: 30 patients with pelvic organ prolapse and stress urinary incontinence, 30 continent women with pelvic organ prolapse and 30 controls. Tissue samples from the participants were obtained from the insertion sites of the uterosacral and cardinal ligaments at the time of hysterectomy. Immunostaining defined relaxin expression intensity. Results: There are statistically significant differences regarding the intensity of relaxin expression between women with pelvic organ prolapse plus stress urinary incontinence and continent women with or without pelvic organ prolapse, as well as between women with prolapse plus incontinence and controls (P<0.05). Continent women with prolapse and controls were more likely to have negative relaxin expression than incontinent women with prolapse. Not any statistically significant differences were found between women with both prolapse and incontinence and women with prolapse only, as well as between continent women with prolapse and controls. Incontinent patients with prolapse had a higher probability of having positive relaxin expression than controls. No women with prolapse and only one control had strongly positive relaxin expression. Conclusions: Positive relaxin expression in pelvic connective tissue could be a predisposing factor for pelvic organ prolapse and/or stress urinary incontinence. Possible future interventions based on relaxin expression may aid in the non-surgical management of pelvic organ prolapse and stress urinary incontinence.