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

BACKGROUND: Quantitative biomechanical characterization of pelvic supportive structures and functions in vivo is thought to provide insight into pathophysiology of pelvic organ prolapse (POP). An innovative approach—vaginal tactile imaging—allows 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 from vaginal walls under an applied tissue deformation and during pelvic floor muscle contractions. OBJECTIVE: To explore an extended set of 52 biomechanical parameters for differentiation and characterization of POP relative to normal pelvic floor conditions. METHODS: 96 subjects with normal and POP conditions were included in the data analysis from multi-site observational, case-controlled studies; 42 subjects had normal pelvic floor conditions and 54 subjects had POP. The VTI, model 2S, was used with an analytical software package to calculate automatically 52 biomechanical parameters for 8 VTI test procedures (probe insertion, elevation, rotation, Valsalva maneuver, voluntary muscle contractions in 2 planes, relaxation, and reflex contraction). The groups were equalized for subject age and parity. RESULTS: The ranges, mean values, and standard deviations for all 52 VTI parameters were established. 33 of 52 parameters were identified as statistically sensitive (p < 0.05; t-test) to the POP development. Among these 33 parameters, 11 parameters show changes (decrease) in tissue elasticity, 8 parameters show deteriorations in pelvic support and 14 parameters show weakness in muscle functions for POP versus normal conditions. CONCLUSIONS: The biomechanical mapping of the female pelvic floor with the VTI provides a unique set of parameters characterizing POP versus normal conditions. These objectively measurable biomechanical transformations of pelvic tissues, support structures, and functions under POP may be used in future research and practical applications.