Effects of vaginal structure and active contractile force on the spatiotemporal evolution of pelvic organ prolapse

Pelvic organ prolapse (POP) significantly impairs women’s quality of life and imposes substantial health and economic burdens. Although finite element (FE) biomechanics have been widely used to study POP, existing models have critical limitations: they simplify the vagina as isolated planar walls rather than an intact tubular structure, and they neglect the vaginal active contractile force (ACF). This study integrates clinical vaginometry with 3D FE simulation to construct a novel model incorporating both the intact tubular vagina and physiological ACF. We measured sustained contractile pressure in 50 healthy volunteers and 30 POP patients and established four comparative simulation groups under graded abdominal impact loads. The results show that the ACF significantly enhances structural elasticity and alleviates tissue injury. Compared with a weak ACF, a normal ACF reduces total tissue damage by 71% quantitatively. Spatiotemporal simulation reveals that damage initiates in the mid-lower anterior vaginal wall. These findings offer biomechanical observations that are consistent with a potential role for pelvic floor muscle training, although further studies are needed.