Biomechanical Mapping of the Female Pelvic Floor: Prolapse versus Normal Conditions

INTRODUCTION: Quantitative biomechanical characterization of pelvic supportive structures and functions in vivo is thought to provide insight into the pathophysiology of pelvic organ prolapse (POP). Vaginal tactile imaging is an innovative approach to the biomechanical mapping of the female pelvic floor to quantify tissue elasticity, pelvic support, and pelvic muscle functions. The Vaginal Tactile Imager (VTI) records high definition pressure patterns through the vaginal walls under an applied tissue deformation and during pelvic floor muscle contractions. OBJECTIVE: The objective of this study is to explore an extended set of 52 biomechanical parameters of the female pelvis for the differentiation and characterization of uterine prolapse relative to normal pelvic floor conditions. METHODS: Sixty subjects were included in the data analysis from observational and case-controlled studies. Out of these 60, forty-two subjects had normal pelvic floor conditions and 18 subjects had uterine prolapse (no anterior, no posterior prolapse). The VTI, model 2S, was used with an analytical software package to automatically calculate 52 biomechanical parameters for 8 VTI test procedures (probe insertion, elevation, rotation, Valsalva maneuver, voluntary muscle contractions in 2 planes, relaxation, and reflex contraction). RESULTS: The ranges, mean values, and standard deviations for all 52 VTI parameters were established. Twenty-two of 52 parameters were identified as statistically sensitive (p < 0.05; t-test) to the development of uterine prolapse. Among these 21 parameters, 6 parameters show changes (decrease) in tissue elasticity, 5 parameters show deteriorations in pelvic support, and 10 parameters show weakness in muscle functions for uterine prolapsed versus normal conditions. CONCLUSION: The biomechanical mapping of the female pelvic floor with the VTI provides a unique set of parameters characterizing uterine prolapse versus normal conditions. These objectively measurable biomechanical transformations of pelvic tissues, support structures, and functions under the prolapse conditions may be useful in future research and practical applications.