Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway; Faculty of Medicine, University of Oslo, Oslo, Norway.
Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway; Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
Am J Obstet Gynecol. 2014 May;210(5):484.e1-7. doi: 10.1016/j.ajog.2014.02.021. Epub 2014 Feb 23.
The objectives of the investigation were to study the association between levator hiatus dimensions in late pregnancy and both the length of second stage of labor and also the delivery mode in women delivering their first child.
In this cohort study, 231 nulliparous women were examined with 3- and 4-dimensional transperineal ultrasonography at 37 weeks of gestation. The anteroposterior, transverse diameter, and the area of levator hiatus were measured at rest, during levator ani muscle contraction, and during Valsalva maneuver. The second stage of labor was divided into passive and active second stage and delivery modes into normal vaginal or instrumental deliveries. Spearman correlation coefficient, independent-sample t test, and standard logistic regression were used for analysis.
Larger levator hiatus dimensions at rest and during contraction at 37 weeks of gestation correlated with a shorter duration of the active second stage in women with normal vaginal delivery (Spearman correlation coefficient, -0.13 to -0.35, P ≤ .08). Women having normal vaginal deliveries had significantly larger transverse diameter at rest, during contraction, and during Valsalva maneuver compared with women having instrumental deliveries (mean difference, 0.29; 95% confidence interval (CI), 0.16-0.41; mean difference, 0.33; 95% CI, 0.21-0.44 and mean difference, 0.24; 95% CI, 0.06-0.42; P < .05). The same was true for the levator hiatus area at rest and during contraction (mean difference, 1.22; 95% CI, 0.37-2.07 and mean difference, 0.84; 95% CI, 0.22-1.46; P < .01). These estimates were unchanged by adjustments in the logistic regression analysis.
Larger levator hiatus dimensions in late pregnancy had a significant association with a shorter active second stage of labor and normal vaginal delivery.
本研究旨在探讨妊娠晚期肛提肌裂孔（levator hiatus）的大小与初产妇第二产程时长及分娩方式之间的关系。
本队列研究纳入了 231 例初产妇，于妊娠 37 周时行 3 维和 4 维经会阴超声检查。在静息、肛提肌收缩和valsalva 动作时测量肛提肌裂孔的前后径、横径和面积。第二产程分为主动和被动阶段，分娩方式分为正常阴道分娩和器械助产。采用 Spearman 相关系数、独立样本 t 检验和标准逻辑回归进行分析。
在正常阴道分娩的产妇中，妊娠 37 周时静息状态和收缩状态下肛提肌裂孔较大与主动第二产程较短相关（Spearman 相关系数，-0.13 至-0.35，P≤0.08）。与行器械助产的产妇相比，行正常阴道分娩的产妇在静息状态、收缩状态和 Valsalva 动作时的横径均明显更大（平均差值，0.29；95%置信区间（CI），0.16-0.41；平均差值，0.33；95%CI，0.21-0.44 和平均差值，0.24；95%CI，0.06-0.42；P<0.05）。肛提肌裂孔在静息和收缩状态时的面积也同样如此（平均差值，1.22；95%CI，0.37-2.07 和平均差值，0.84；95%CI，0.22-1.46；P<0.01）。这些估计值在逻辑回归分析中进行调整后仍保持不变。
妊娠晚期肛提肌裂孔较大与第二产程活跃期较短和正常阴道分娩有显著关联。
