Division of Female Pelvic Medicine and Reconstructive Surgery, Department of Obstetrics and Gynecology, University of Arkansas for Medical Sciences, Little Rock, AR.
Division of Ultrasonography, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh-School of Medicine, Pittsburgh, PA.
Am J Obstet Gynecol. 2018 Feb;218(2):242.e1-242.e7. doi: 10.1016/j.ajog.2017.11.572. Epub 2017 Nov 16.
Parity is the greatest risk factor for the development of pelvic organ prolapse. The normally supported vagina is pulled up and back over the levator ani. Loss of vaginal angulation has been associated with prolapse and may represent injury to the vaginal supportive tissues.
We proposed and examined the following hypotheses: (1) pregnancy and delivery impact vaginal support, leading to loss of vaginal angle; (2) vaginal angulation is restored postpartum; and (3) uncomplicated vaginal delivery (VD) is associated with accelerated remodeling of the vaginal fibrillar matrix.
We prospectively enrolled a cohort of nulliparas in the first trimester of pregnancy, and abstracted demographic and delivery data. Metalloproteinase 9 (MMP-9) activity in the vagina was determined in the first and third trimesters and 1 year postpartum using a substrate activity assay. Uncomplicated VD was defined as none of the following: cesarean delivery, forceps or vacuum use, shoulder dystocia, obstetric anal sphincter laceration, or prolonged second-stage labor. Women were grouped dichotomously for comparison based on this definition. A subset of participants underwent transperineal ultrasound.
We enrolled 173 women with mean age of 25 ± 6 years and a body mass index of 20 ± 7 kg/m. Of the women, 67% identified as white/Caucasian, 27% black/African American, or 6% Hispanic/Latina. The mean delivery age was 39 ± 3 weeks, with 59% of participants experiencing uncomplicated VD. The MMP-9 median activity (ng/mg protein) was 242.0 (IQR, 18.7, 896.8; n = 157) in the first trimester, 130.8 (IQR, 14.6, 883.8; n = 148) in the third trimester, and 463.5 (IQR, 92.2, 900.0; n = 94) postpartum. The MMP-9 activity increased between the third trimester and 1 year postpartum (P = .006), with no significant difference between MMP-9 values in the first and third trimesters (P = .674). The vaginal angle became less acute from the first to the third trimester, and this change persisted postpartum. The vaginal angulation over the levator plate became more acute between the third trimester and postpartum in women who experienced uncomplicated VD compared to those who did not (-6.4 ± 22.1 degrees vs 17.5 ± 14.8 degrees; P = .017). Higher MMP-9 activity postpartum was associated with uncomplicated VD, with 67% of women in the third tertile achieving uncomplicated VD versus 39% in the first tertile (P = .029).
Loss of vaginal angulation occurs between trimesters, and women do not recover their baseline resting angle postpartum. MMP-9 activity increases postpartum. Women experiencing uncomplicated VD demonstrate higher postpartum MMP-9 activity and are more likely to have recovered their vaginal angle.
妊娠和分娩是导致盆腔器官脱垂的最大危险因素。正常支撑的阴道向上向后牵拉，越过会阴肌。阴道角度的丧失与脱垂有关，可能代表阴道支持组织的损伤。
我们提出并检验了以下假设：（1）妊娠和分娩会影响阴道的支撑，导致阴道角度的丧失；（2）阴道角度在产后恢复；（3）单纯阴道分娩（VD）与阴道纤维状基质的快速重塑有关。
我们前瞻性地招募了一组处于妊娠早期的初产妇，并提取了人口统计学和分娩数据。在妊娠第 1 期和第 3 期以及产后 1 年，使用基质活性测定法测定阴道中基质金属蛋白酶 9（MMP-9）的活性。单纯 VD 的定义为以下情况均不存在：剖宫产、产钳或真空使用、肩难产、产科肛门括约肌撕裂或第二产程延长。根据这一定义，将女性分为两组进行比较。部分参与者接受了经会阴超声检查。
我们共招募了 173 名平均年龄 25 ± 6 岁、体重指数 20 ± 7 kg/m²的初产妇。其中，67%为白人/高加索人，27%为黑人/非裔美国人，6%为西班牙裔/拉丁裔。产妇的平均分娩年龄为 39 ± 3 周，59%的参与者经历了单纯 VD。MMP-9 的中位数活性（ng/mg 蛋白）在妊娠第 1 期为 242.0（IQR，18.7，896.8；n=157），在妊娠第 3 期为 130.8（IQR，14.6，883.8；n=148），在产后为 463.5（IQR，92.2，900.0；n=94）。MMP-9 活性在妊娠第 3 期和产后 1 年之间增加（P=0.006），但妊娠第 1 期和第 3 期之间的 MMP-9 值无显著差异（P=0.674）。阴道角度从妊娠第 1 期到第 3 期变得不那么尖锐，这种变化在产后持续存在。与未经历单纯 VD 的女性相比，经历单纯 VD 的女性在妊娠第 3 期和产后期间，阴道在会阴板上的角度变得更加尖锐（-6.4 ± 22.1 度与 17.5 ± 14.8 度；P=0.017）。产后 MMP-9 活性较高与单纯 VD 有关，第 3 tertile 中有 67%的女性实现了单纯 VD，而第 1 tertile 中只有 39%（P=0.029）。
阴道角度在妊娠期间丧失，且女性在产后无法恢复其基线静息角度。MMP-9 活性在产后增加。经历单纯 VD 的女性产后 MMP-9 活性较高，且更有可能恢复阴道角度。
