目的: 探讨孕晚期初产妇肛提肌裂孔大小、第二产程长度与分娩方式的相关性,为临床分娩方式选择提供参考。方法: 选取2022年1月-2025年3月于我院接受晚孕期(36～40周)检查的单胎初产妇330例,经会阴实时三维盆底超声测量静息、Valsalva动作及缩肛状态下肛提肌裂孔前后径、左右径及肛提肌裂孔面积。按分娩方式分为经阴道分娩组(197例)和中转剖宫产组(108例),统计分析肛提肌裂孔参数、第二产程长度与分娩方式的相关性。结果: 经阴道分娩组在静息状态、缩肛状态及Valsalva状态下肛提肌裂孔前后径、左右径及面积明显大于剖宫产组,经阴道分娩产妇静息状态及Valsalva状态下肛提肌裂孔前后径及面积与第二产程时长存在负相关。结论: 初产妇肛提肌裂孔大小、第二产程长度与分娩方式密切相关,较小的肛提肌裂孔可能增加阴道分娩难度并中转剖宫产;孕晚期盆底超声参数可一定程度预判分娩方式,为产科精准决策及个性化分娩方案制定提供依据。
Objective: To investigate the correlation among levator hiatus size, duration of the second stage of labor, and mode of delivery in primiparous women during late pregnancy, and to provide evidence for clinical decision-making on delivery mode selection. Methods: A total of 330 singleton primiparas with 36-40 weeks of gestation who underwent routine prenatal examinations in our hospital from January 2022 to March 2025 were prospectively enrolled. Transperineal real-time three-dimensional pelvic floor ultrasound was performed to measure the anteroposterior diameter, transverse diameter, and area of the levator hiatus at rest, during Valsalva maneuver, and active anal contraction. According to the final delivery mode, the subjects were divided into the vaginal delivery group (n=197) and the intrapartum cesarean section group (n=108). Statistical analyses were conducted using Pearson correlation coefficient and independent samples t-test to explore the correlations among levator hiatus parameters, duration of the second stage of labor, and delivery mode. Results: Compared with the intrapartum cesarean section group, the vaginal delivery group had significantly larger anteroposterior diameter, transverse diameter, and area of the levator hiatus at rest, during anal contraction, and Valsalva maneuver. In the vaginal delivery group, the anteroposterior diameter and area of the levator hiatus at rest and during Valsalva maneuver were negatively correlated with the duration of the second stage of labor. Conclusions: Levator hiatus size and duration of the second stage of labor are closely associated with the delivery mode in primiparous women. A smaller levator hiatus may increase the difficulty of vaginal delivery and elevate the risk of intrapartum cesarean section. Pelvic floor ultrasound-derived levator hiatus parameters in late pregnancy can serve as predictive indicators for delivery mode, which is beneficial for precise obstetric management and individualized delivery plan formulation.
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