Mechanics-based Metrics for Vaginal Tear Evaluation

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Around 80 percent of women experience vaginal tears during labor, when the diameter of the vagina has to increase from 2.5 cm to 9.5 cm in order to allow the passage of a full-term baby. Complications associated with vaginal tears include postpartum hemorrhaging, fecal incontinence, urinary incontinence, and dyspareunia. Current evaluation methods of vaginal tears after childbirth are qualitative and rely on the expertise and training of obstetricians and midwives. This reliance upon subjective assessments often leads to incorrect diagnosis and inadequate treatment that severely compromise the quality of life of women. In order to establish new quantitative metrics for evaluating vaginal tears, a seamless experimental, theoretical, and computational characterization of the mechanical properties of the vagina -- including the tear resistance properties -- will be studied. This project will examine fundamental mechanical properties and response of this very under-studied tissue. The knowledge gained will support improved understanding of the response of vaginal tissue to the natural stretch that occurs during childbirth, and this will then support improved diagnostic, assessment, and treatment methods. Undergraduate and graduate students, mostly from underrepresented groups, will be recruited to participate in this highly interdisciplinary research and education program, which involves synergistic exchanges between the medical and STEM fields. In addition, in order to inspire, prepare, and empower undergraduate women to pursue graduate studies in engineering and help close the gender gap, a new one-day workshop offering preparatory information about graduate school will be organized at Virginia Tech. In order to meet these project goals, entire vaginal canals from virgin and late pregnant rats will be subjected to inflation tests to induce tearing, and the resulting large inhomogeneous deformations will be measured using the digital image correlation technique. By using multi-photon microscopy and second harmonic generation imaging, the collagen fiber organization in the near- and far-fields of the tears will be measured. The experimental data will guide the development of new microstructurally-based constitutive models for the vaginal wall that are validated using a highly efficient data-driven reduced order modeling approach. Finally, new mechanics-based metrics for vaginal tear evaluation will be established following the theory of critical distances approach, using both the experimental data and data-driven models. This will include markers for levator ani trauma, predictors for maternal trauma, and protocols for pelvic floor trainer devices.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.