Objective

The aim our study was to evaluate the association between the antepartum clinical measurement of the Bituberous Diameter (BTD) and the occurrence of unplanned obstetrical intervention (UOI) due to labor dystocia, including either operative vaginal delivery or caesarean section in a cohort of low-risk, nulliparous at term.

Design

Retrospective analysis of prospectively collected data.

Setting

Tertiary maternity care.

Interventions

With the women lying in lithotomic the distance between two ischial tuberosities was assessed using a tape measure during the routine antenatal booking between 37 and 38 weeks of gestation.

Measurements and findings

Overall, 116 patient were included, and of these 23(19.8%) were submitted to an UOI due to labor dystocia. Compared to women that had a spontaneous vaginal delivery, women submitted to an UOI had a shorter BTD (8.25 + 0.843 vs 9.60 + 1.12, p < 0.001), a higher frequency of epidural analgesia (21/23 or 91.3% vs 50/93 or 53.8%; p = 0.002) and of augmentation of labor (14/23 or 60.9% vs 19/93 or 20.4%; p < 0.001) as well as a longer first [455 (IQR 142–455 min vs 293 (IQR 142–455) min] and second stages of labor [129 (IQR 85–155) min vs 51 (IQR 27–78) min]. Multivariable logistic regression showed that the BTD (aOR 0.16, 95% CI 0.04–0.60; p = 0.007) and the length of the second stage of labor (aOR 6.83, 95% CI 2.10–22.23; p = 0.001) were independently associated with UOI. When evaluating the diagnostic accuracy of the BTD for the prediction of UOI due to labor dystocia, the BTD showed an AUC of 0.82 (95 %CI 0.73–0.91; p < 0.001) with an optimal cut-off value of 8.6 cm (78.3% (95 %CI 56.3–92.5) sensitivity, 77.4% (95 %CI 67.6–85.4) specificity, 46.2% (95% CI 30.1–62.8) PPV, 93.5% (95% CI 85.5–97.9) NPV, 3.5 (95% CI 2.3–5.4) positive LR, and 0.28 (95% CI 0.13–0.61) negative LR. A significant inverse correlation between the length of the second stage of labour and the BTD in patients that had a vaginal delivery was also demonstrated (Spearman’s rho = -0.24, p = 0.01).

Key conclusions

Our study suggests that antepartum clinical assessment of the BTD might be used as a reliable predictor of UOI due to labor dystocia in low-risk, nulliparous women at term gestation.

Implications for practice

Antenatal identification of women at higher risk for labor dystocia might trigger some interventions during the second stage of labor, such as maternal position shifting, to increase the pelvic capacity and potentially improve outcomes or might prompt a referral of the patient to a district hospital prior to the onset of labor.

中文翻译：

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低风险未产妇队列中双性生殖直径与分娩方式之间的相关性

客观的

我们研究的目的是评估产前临床测量的双乳直径 (BTD) 与因难产导致的计划外产科干预 (UOI) 发生率之间的关联，包括在一组低产儿中进行阴道手术分娩或剖腹产。风险，足月未产。

设计

对前瞻性收集的数据进行回顾性分析。

环境

三级产妇护理。

干预措施

对于处于截石位的妇女，在妊娠 37 至 38 周之间的常规产前预约期间，使用卷尺评估两个坐骨结节之间的距离。

测量和结果

总体而言，共纳入 116 名患者，其中 23 名患者（19.8%）因难产而接受 UOI。与自然阴道分娩的女性相比，接受 UOI 的女性的 BTD 更短（8.25 + 0.843 vs 9.60 + 1.12，p < 0.001），硬膜外镇痛频率更高（21/23 或 91.3% vs 50/93）或 53.8%；p = 0.002）和增加产程（14/23 或 60.9% vs 19/93 或 20.4%；p < 0.001）以及较长的第一次 [455（IQR 142–455 分钟 vs 293） 142–455) 分钟] 和第二产程 [129 (IQR 85–155) 分钟 vs 51 (IQR 27–78) 分钟]。多变量逻辑回归显示 BTD（aOR 0.16，95% CI 0.04–0.60；p = 0.007）和第二产程时长（aOR 6.83，95% CI 2.10-22.23；p = 0.001）与 UOI 独立相关。5% (95% CI 85.5–97.9) NPV、3.5 (95% CI 2.3–5.4) 阳性 LR 和 0.28 (95% CI 0.13–0.61) 阴性 LR。还证明了阴道分娩患者的第二产​​程时长与 BTD 之间存在显着的负相关（Spearman's rho = -0.24，p = 0.01）。5% (95% CI 85.5–97.9) NPV、3.5 (95% CI 2.3–5.4) 阳性 LR 和 0.28 (95% CI 0.13–0.61) 阴性 LR。还证明了阴道分娩患者的第二产​​程时长与 BTD 之间存在显着的负相关（Spearman's rho = -0.24，p = 0.01）。

主要结论

我们的研究表明，对于低风险、足月妊娠的未产妇来说，BTD 的产前临床评估可以作为因难产导致的 UOI 的可靠预测指标。

对实践的影响

对产前难产风险较高的妇女进行产前识别可能会在第二产程期间引发一些干预措施，例如产妇体位改变，以增加骨盆容量并可能改善结果，或者可能会促使患者在产前转诊至地区医院临产的开始。