Study On Neuromuscular Pathology Of The Pelvic Floor On Primipara After Pregnancy And Vaginal Delivery

Objective 1,To investigate the effect of pregnancy and spontaneous delivery on the pelvic floor, we studied the pathologic characteristics of the levator ani muscle and innervation of the vaginal mucosa.2,To investigate the neuromuscular characteristics of the pelvic floor of women with urinary incontinence during pregnancy and after spontaneous delivery, we studied the pathologic changes of the levator ani muscle and innervation of the vaginal mucosa.3,To investigate the neuromuscular characteristics of the pelvic floor of women with pelvic floor prolapse during pregnancy and after spontaneous delivery, we studied the pathologic changes of the levator ani muscle and innervation of the vaginal mucosa.Methods One hundred primipara were collected in the study whose symptomps of urinary incontinence(UI) and pelvic organ prolapse(POP) were assessed by International Consultation on Incontinence Questionnaire Female Lower Urinary Tract Symptoms Module (ICIQ-FLUTS) and The pelvic organ prolapse quantitative examination (POP-Q) respectively. Meanwhile, pelvic floor electromyogram was performed. After the third stage of labor, biopsy specimens of levitor ani muscle(LAM) and anterior and posterior vagina wall were obtained from the puerpera as well as from 8 healthy nullipara under vaginal operation.LAMs' s structure were stained with the following histological techniques: HE staining, ATPase staining, modified Gomori staining, NSE staining, ACP staining and oil red O staining and were examined for the morphological changes, classifying and measuring the muscular fibers.Vaginal mucosa specimens were stained with the following immunohistochemistry staining: PGP9.5,VIP and NPY staining, and the positive stained nerve fibers were calculated respectively.Results(1) Seventy--five primipara undergone spontaneous delivery among whom sixty-four LAMs' s specimens were obtained, in which thirty-nine had striated muscle tissue (60.9%).(2) The LAMs of the puerperal undergoing vaginal delivery presented neurogenetic and myogenetic changes, both acute and chronic. Type I muscular fibers were predominant with both types increasing in diameters.(3) Significantly different (P＜0.05) innervation of PGP9.5,VIP and NPY nerve fibers was observed between epithelial lamina of anterior vaginal wall and that of posterior vaginal wall, with the nerve fibers being more in epithelial lamina of anterior vaginal wall, while no difference (P＜0.05) of the innervation of nerve fibers was observed in the lamina propria.(4) Significantly different (P＜0.05) innervation of PGP9.5 and VIP nerve fibers was observed in the lamina propria of the anterior vaginal wall in puerperal undergoing vaginal delivery compared with those in nullipara.(5) The type I muscular fibers were predominant in LAMs no matter whether UI occurred and no significant difference (P＞0.05) was observed between patients with UI and those without UI as far as the diameters and ratio of muscular fibers were concerned.(6) Innervation of rIP nerve fibers in the lamina propria of the anterior vaginal wall was different (P＜0.05) between patients with UI and those without UI after vaginal delivery.(7) Parturient with UI had experienced a longer duration in the second stage of labor than those without UI. Furthermore, parturients with UI that only occurred after delivery had experienced a longer duration in the second stage of labor than those without UI either before or after delivery. Elongation of the second stage of labor is the risk factor of UI after vaginal delivery (Logistic regression coefficient=0.028, P=0.028).(8) No difference was observed between parturient with POP and without POP concerning the diameters and ratio of muscular fibers (P＞0.05).(9) There was a significant difference (P＜0.05) in the diameters of typeⅡmuscular fibers as well as the innervation of VIP and NPY nerve fibers between parturient with POP and without POP.Conclusions1,It is indicated that injuries may take place in pelvic floor muscles and nerves after labour and delivery under the pressure and stretch by fetal head, as evidenced by the fact that the LAMs of the puerpera undergoing vaginal delivery presented neurogenetic and myogenetic changes, both acute and chronic.2,The change of proportion of typeⅠand typeⅡmuscular fibers after labour and delivery demonstrated denervation of pelvic floor muscles due to injuries of their governing nerves. Adaptation of pelvic floor muscles to gestation and compensation for the atrophy muscular fibers resulted in distinguished hypertrophy in typeⅠand typeⅡmuscular fibers which might recover to their original state after a period postpartum.3,The nerve fibers were more abundant in epithelial lamina of anterior vaginal wallthan that of the posterior wall.4,Richer innervation of PGP9.5 and VIP nerve fibers in the lamina propria of the anterior vaginal wall in puerperal undergoing vaginal delivery is beneficial for dilation of the blood vessels and smooth muscles and makes preparation for delivery.5,The changes of morphology, muscular fiber diameters and proportions in LAMs of parturient were neither directly associated with UI nor with POP postpartum.6,Decrease innervation of VIP nerve fibers in the lamina propria of the anterior vaginal wall may contribute to the pathogenesis of UI after delivery. Different innervation of rIP and NPY nerve fibers in the lamina propria of the anterior vaginal wall may contribute to the pathogenesis of POP after delivery, but not contribute to the pathogenesis of POP during pregnancy.7,Enlogation of second stage of labor constitutes a risk factor for postpartum UI.