Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, OR.
Department of Women's Health, Dell School of Medicine, The University of Texas at Austin, Austin, TX.
Am J Obstet Gynecol. 2022 May;226(5):718.e1-718.e10. doi: 10.1016/j.ajog.2022.02.020. Epub 2022 Feb 22.
Evidence of detachment of the levator ani muscle system is seen more frequently in patients with pelvic floor disorders. It has been suggested that passive descent of the fetus before pushing could be used to decrease operative vaginal delivery and levator ani muscle injury.
This planned analysis aimed to determine whether immediate or delayed pushing was associated with an increased proportion of injury to the levator ani muscle system after the first delivery among nulliparous women.
The Optimizing Management of the Second Stage study was a multicenter randomized trial. Nulliparous women with term pregnancies and neuraxial analgesia were randomly assigned at complete cervical dilation to either immediate pushing or delayed pushing for 1 hour. A subset of participants consented to longitudinal objective pelvic floor assessments: (1) during postpartum stay (initial), (2) at 6 weeks (postpartum 1), and (3) at 6 months (postpartum 2) with transperineal 3-dimensional ultrasound. Following the completion of all visits by all subjects, saved 3-dimensional ultrasound volumes were assessed in a masked fashion. The outcome was "occult" levator ani muscle injury on the right or left, defined as a widening of the attachment of the levator ani to its origin utilizing the levator-urethra gap measurement. Measurements and proportions were compared between the 2 groups by study visit using the χ test or Fisher exact test for categorical variables and the t test or Mann-Whitney U test for continuous variables as appropriate.
Here, 941 of 2414 randomized subjects (39.0%) participated in the pelvic floor assessments: 452 in the immediate pushing group and 489 in the delayed pushing group. We obtained sonograms on 67%, 83%, and 77% of the pelvic floor assessment participants at the initial, postpartum 1, and postpartum-2 visits, respectively. Demographic and labor characteristics were comparable between the 2 groups; 94% of participants were non-Hispanic, and 50% of participants were Black. Levator ani muscle injury was noted in 77 participants (13.6%) at the initial visit, 99 (13.1%) at PP1, and 72 (10.6%) at PP2. There was no difference in injury between women in the immediate pushing group and women in the delayed pushing group. These findings did not change when the threshold (sensitivity) of levator ani muscle injury was adjusted to a less conservative measure.
Among nulliparous women at term with neuraxial analgesia, the rates of occult levator ani muscle injury were not different between women undergoing immediate pushing and women undergoing delayed pushing in the second stage of labor. Further research efforts are needed to understand the development and potential prevention of subsequent pelvic floor disorders.
在患有盆底功能障碍的患者中，更常观察到肛提肌系统分离的证据。有人提出，在用力推之前让胎儿被动下降可能会减少阴道助产和肛提肌损伤。
本计划分析旨在确定初产妇中，第一产程中立即或延迟用力与肛提肌系统损伤的比例增加是否相关。
优化第二产程管理研究是一项多中心随机试验。足月妊娠并接受椎管内镇痛的初产妇在完全宫颈扩张时随机分为立即用力组或 1 小时后延迟用力组。部分参与者同意进行纵向客观盆底评估：（1）产后留观期间（初始），（2）产后 6 周（产后 1 期），（3）产后 6 个月（产后 2 期），采用经会阴 3 维超声。所有受试者完成所有访视后，以盲法评估保存的 3 维超声容积。结果为右侧或左侧“隐匿性”肛提肌损伤，定义为利用肛提肌-尿道间隙测量值，肛提肌与起点的附着处变宽。通过 χ 检验或 Fisher 确切检验比较 2 组的分类变量，t 检验或 Mann-Whitney U 检验比较 2 组的连续变量。
在 2414 名随机受试者中，有 941 名（39.0%）参加了盆底评估：立即用力组 452 名，延迟用力组 489 名。在初始、产后 1 期和产后 2 期访视时，分别有 67%、83%和 77%的盆底评估参与者获得了超声图像。2 组间的人口统计学和分娩特征无差异；94%的参与者为非西班牙裔，50%为黑人。在初始访视时，77 名（13.6%）参与者、99 名（13.1%）参与者和 72 名（10.6%）参与者在产后 1 期和产后 2 期发现肛提肌损伤。立即用力组和延迟用力组的妇女在损伤方面无差异。当将肛提肌损伤的阈值（敏感性）调整为更保守的测量值时，这些发现并未改变。
在接受椎管内镇痛的足月初产妇中，第二产程中立即用力和延迟用力的产妇隐匿性肛提肌损伤发生率无差异。需要进一步研究以了解随后盆底功能障碍的发展和潜在预防。
