Influence of body mass index on the biomechanical properties of the human prolapsed anterior vaginal wall

Introduction and hypothesis: We report the influence of body mass index (BMI) on the biomechanical properties of human prolapsed anterior vaginal wall (AVW) tissue samples. We hypothesize that women with AVW prolapse would have the same vaginal wall biomechanical properties regardless of their weight. Methods: Following Institutional Review Board approval, age-comparable postmenopausal women with symptomatic stage II–III AVW prolapse underwent excision of a short vaginal wall sample during transvaginal prolapse repair. Excised samples were subjected to uniaxial tensile testing using an Instron 5655 (Instron, Norwood, MA, USA) within 2 h of harvest to measure intrinsic biomechanical properties. Patients were divided into two groups (A: BMI <25 and B: BMI >25) to compare tissue biomechanical properties after controlling for age and parity. Results: From 2011 to 2013, 28 consecutive women were studied, 13 in group A and 15 in group B. Patients with BMI >25 developed higher tissue stresses, including higher tangent moduli, at selected strain levels than patients with BMI <25. Conclusions: Contrary to our hypothesis, this study observed a relationship between BMI and human AVW biomechanical properties, with more obese women having stiffer tissue properties.