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12: Pelvic organ prolapse surgery improves biomechanical conditions and integrity of the weak pelvic floor

      Objectives

      The objective of this study is to identify pre-surgical biomechanical conditions of the pelvic floor which allow improvements of biomechanical parameters in the results of pelvic organ prolapse surgery.

      Materials and Methods

      This multisite clinical study was designed to explore changes in tissue elasticity, pelvic support, and certain functions (contractive strength, muscle relaxation speed, muscle motility) after pelvic organ prolapse (POP) surgery. A biomechanical mapping of the pelvic floor was performed before and 4 to 6 months after the surgery. The biomechanical data for 52 parameters were acquired by vaginal tactile imaging (VTI) for manually applied deflection pressures to vaginal walls and pelvic muscle contractions. The two-sample t-test (p < 0.05) was employed to test the null hypothesis that pre-surgery data in Group 1 (positive parameter change after surgery) and pre-surgery data in Group 2 (negative parameter change after surgery) belonged to the same distribution.

      Results

      Seventy-eight subjects with 255 surgical procedures were analyzed across five participating clinical sites. All 52 t-tests for Group 1 versus Group 2 had p-value in the range form 4.0*10-10 to 4.3*10-2 associating all of the 52 parameter changes after surgery with the pre-surgical conditions. The p-value of before and after surgery correlation ranged from 3.7*10-18 to 1.6*10-2 for 50 of 52 tests with Pearson correlation coefficient ranging from -0.79 to -0.27. Results for two parameters are shown in Figures 1 and 2. This means that post-surgical changes of VTI parameters have negative correlation with the pre-surgical values of these parameters. These observed negative correlations indicate that POP surgery improves pelvic floor conditions for low values of the biomechanical parameters, associated with weak pelvic floor conditions. Positive change or improvement in VTI parameters after a surgical procedure signifies: (a) an increase in pressure response value (kPa) at the same tissue deformation, (b) an increase in pressure gradient value (stress-to-strain ratio, kPa/mm), which relates to tissue elasticity, (c) an increase of contractive pressure or force value (kPa or N) from a pelvic muscles, (d) a decrease of muscle relaxation speed (kPa/s), or an increase in mobility of a pelvic muscle along the vagina (mm). The integrity of the pelvic floor with low pre-surgical biomechanical parameters is also improved.

      Conclusion

      Pelvic organ prolapse surgery, in general, improves the biomechanical conditions and integrity of the weak pelvic floor.
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