MRI-based analysis of amniotic membrane mechanical response patterns and rupture risk stratification in PROM and PPROM

Objective: To develop a proof-of-concept MRI-based biomechanical framework for assessing full-field amniotic membrane responses under contraction-induced, fluid-mediated loading and preliminarily exploring their relevance to PROM/PPROM rupture risk. Methods: Subject-specific amniotic sac geometries were reconstructed from MRI data using semi-automated segmentation and incorporated into an integrated finite element model of the gravid abdomen. Amniotic fluid was modeled as nearly incompressible, and time-varying uterine contraction pressures were transmitted to the amniotic membrane under quasi-static conditions. Strain energy density(SED) and maximum principal stress were quantified, and robust z-scores were used to preliminarily assess inter-subject rupture-risk patterns. Results: In five pregnant women, SED and maximum principal stress showed pronounced spatial heterogeneity and were substantially amplified by coupled uterine contraction–amniotic fluid loading. Compared with equal-volume ellipsoidal models, MRI-based individualized models produced distinct response magnitudes and spatial localizations. Higher robust z-score–based mechanical metrics tended to occur in subjects with earlier gestational ages at delivery, suggesting preliminary consistency with clinical risk-related status. Conclusion: This proof-of-concept MRI-based framework demonstrates the feasibility of assessing spatially heterogeneous amniotic membrane mechanics under contraction-induced, fluid-mediated loading. The derived metrics may inform future PROM/PPROM risk assessment but require validation in larger clinical cohorts.