Vaginal biomechanical function in premenopausal and postmenopausal women with and without pelvic organ prolapse

The vagina plays a vital role in childbirth, and compromised vaginal mechanical integrity can lead to pelvic organ prolapse (POP). Animal studies highlight the biaxial mechanical response of pelvic organs, however, it has not yet been assessed in the human vagina with POP. Therefore, the objective of this study was to quantify the biaxial biomechanical properties of vaginal tissue in pre-and postmenopausal women across POP stages. In postmenopausal patients, circumferential toe-region modulus decreased in POP-III compared to POP-II (p = 0.041), and longitudinal toe-region modulus decreased in POP-III compared to non-POP and POP-II (p = 0.026 and 0.031). Conversely, no statistically significant changes were observed in premenopausal patients across POP stages. Directional differences in vaginal modulus were evident in premenopausal non-POP and POP-II (p = 0.006 and 0.001) but were absent in POP-III and postmenopausal groups. These findings suggested that POP impacts vaginal biomechanics differently in pre-and postmenopausal women, likely reflecting distinct underlying processes. Additionally, a preliminary study using non-destructive 3D microscopy demonstrated the potential for whole-tissue microstructure quantification of the vagina. Further investigation into the microstructural changes of vaginal tissue is essential to better understand these differences and guide the development of targeted interventions for POP.