Evaluation On The Influence Of Delivery On Morphology And Elasticity Of Levator Ani Muscle By Three Dimensional-pelvic Floor Ultrasound Combined With Shear Wave Elastography

Objective:The levator hiatal areas at rest,contraction and maximal valsalva state in primiparas were measured by transperineal three-dimensional ultrasound(3DUS).the Young's modulus values of puborectalis(PR)at rest and contraction state in primiparas were measured by shear wave elastography(SWE).To explore the effect of different delivery modes and the duration of second stage of labor on the morphological and elastic parameters of levator ani muscle.Methods:A total of 105 primiparas with full-term single birth(2.5-4.0kg newborn weight)in our hospital to examine at postpartum42 days from october 2018 to september 2019 were enrolled.According to the delivery mode,they were divided into 40 caesarean section cases and65 vaginal delivery cases.The vaginal delivery group was then divided into two groups according to the duration of the second labor(t):t<3 h(T1group,40cases),t ?3 h group(T2 group,25 cases).At the same time,30 healthy nulliparous women who has sexual life history were selected as the control group.The levator hiatal areas at rest,contraction and maximal valsalva state were measured by 3DUS.The Young's modulus value of bilateral PR was measured with SWE at rest and contraction state respectively and difference before and after contraction was calculated.Results:1.At rest,contraction and maximal valsalva state,the levator hiatal area of the caesarean section group,vaginal delivery group(T1group)and vaginal delivery group(T2 group)was more than that in the control group,and the differences were of statistical significance(P<0.05).Difference of the levator hiatal area of the cesarean section group and vaginal delivery group(T1group)was of no statistical significance(P>0.05).the levator hiatal area of the vaginal delivery group(T2 group)was more than that in the the caesarean section group and vaginal delivery group(T1group),and the differences were of statistical significance(P<0.05).2.At rest and contraction state,the elasticity parameters of of the caesarean section group,vaginal delivery group(T1group)and vaginal delivery group(T2 group)were less than those in the control group,and the differences were of statistical significance(P<0.05).Difference of the elasticity parameters of the cesarean section group and vaginal delivery group(T1group)was of no statistical significance(P>0.05).the elasticity parameters of the vaginal delivery group(T2 group)were less than those in the the caesarean section group and vaginal delivery group(T1group),and the differences were of statistical significance(P<0.05).Conclusion:1.Pregnancy and delivery can lead to the blooming of the levator hiatal area.A prolonged second stage of labor is more likely to lead to the blooming of levator hiatus.2.The PR elasticity decreases in the early postpartum women.Aprolonged second stage of labor is more likely to reduce PR elasticity and contractile function.3.It is feasible for SWE to evaluate the elasticity and contractile function of parturient women.Ultrasound can be used as an effective method for evaluating the pelvic floor function of postpartum women.