Abstract：
Labor arrest is estimated to account for approximately one-third of all primary cesarean deliveries, and is associated with an increased risk of adverse maternal and perinatal outcomes. One of the main causes is the mismatch between the size of the birth canal and that of the fetus, a condition usually referred to as cephalopelvic disproportion.
This study aimed to describe a new ultrasound predictor of labor arrest leading to cesarean delivery because of suspected cephalopelvic disproportion.
This was a multicenter prospective study conducted at 3 maternity units from January 2021 to January 2022. A nonconsecutive series of singleton pregnancies with cephalic-presenting fetuses, gestational age of 34 weeks+0 days or above, and no contraindication to vaginal delivery attending at the antenatal clinics of each institution were considered eligible. Between 34+0 and 38+0 weeks of gestation, all eligible patients were submitted to transabdominal 2D ultrasound measurement of the obstetrical conjugate. On admission to the labor ward, the fetal head circumference was measured on the standard transthalamic plane by transabdominal ultrasound. The primary outcome of the study was the accuracy of the ratio between the fetal head circumference and the obstetrical conjugate measurement (ie, head circumference/obstetrical conjugate ratio) in predicting the occurrence of cesarean delivery secondary to labor arrest. The secondary outcome was the relationship between the head circumference/obstetrical conjugate ratio and labor duration.
A total of 263 women were included. Cesarean delivery for labor arrest was performed in 7.6% (20/263) of the included cases and was associated with more frequent use of epidural analgesia (95.0% vs 45.7%; P<.001), longer second stage of labor (193 [120-240] vs 34.0 [13.8-66.5] minutes; P=.002), shorter obstetrical conjugate (111 [108-114] vs 121 [116-125] mm; P<.001), higher head circumference/obstetrical conjugate ratio (3.2 [3.2-3.35] vs 2.9 [2.8-3.0]; P<.001), and higher birthweight (3678 [3501-3916] vs 3352 [3095-3680] g; P=.003) compared with vaginal delivery. At logistic regression analysis, the head circumference/obstetrical conjugate ratio expressed as Z-score was the only parameter independently associated with risk of cesarean delivery for labor arrest (odds ratio, 8.8; 95% confidence interval, 3.6-21.7) and had higher accuracy in predicting cesarean delivery compared with the accuracy of fetal head circumference and obstetrical conjugate alone, with an area under the curve of 0.91 (95% confidence interval, 81.7-99.5; P<.001). A positive correlation between the head circumference/obstetrical conjugate ratio and length of the second stage of labor was found (Pearson coefficient, 0.16; P=.018).
Our study, conducted on an unselected low-risk population, demonstrated that the head circumference/obstetrical conjugate ratio is a reliable antenatal predictor of labor arrest leading to cesarean delivery.
This study aimed to describe a new ultrasound predictor of labor arrest leading to cesarean delivery because of suspected cephalopelvic disproportion.
This was a multicenter prospective study conducted at 3 maternity units from January 2021 to January 2022. A nonconsecutive series of singleton pregnancies with cephalic-presenting fetuses, gestational age of 34 weeks+0 days or above, and no contraindication to vaginal delivery attending at the antenatal clinics of each institution were considered eligible. Between 34+0 and 38+0 weeks of gestation, all eligible patients were submitted to transabdominal 2D ultrasound measurement of the obstetrical conjugate. On admission to the labor ward, the fetal head circumference was measured on the standard transthalamic plane by transabdominal ultrasound. The primary outcome of the study was the accuracy of the ratio between the fetal head circumference and the obstetrical conjugate measurement (ie, head circumference/obstetrical conjugate ratio) in predicting the occurrence of cesarean delivery secondary to labor arrest. The secondary outcome was the relationship between the head circumference/obstetrical conjugate ratio and labor duration.
A total of 263 women were included. Cesarean delivery for labor arrest was performed in 7.6% (20/263) of the included cases and was associated with more frequent use of epidural analgesia (95.0% vs 45.7%; P<.001), longer second stage of labor (193 [120-240] vs 34.0 [13.8-66.5] minutes; P=.002), shorter obstetrical conjugate (111 [108-114] vs 121 [116-125] mm; P<.001), higher head circumference/obstetrical conjugate ratio (3.2 [3.2-3.35] vs 2.9 [2.8-3.0]; P<.001), and higher birthweight (3678 [3501-3916] vs 3352 [3095-3680] g; P=.003) compared with vaginal delivery. At logistic regression analysis, the head circumference/obstetrical conjugate ratio expressed as Z-score was the only parameter independently associated with risk of cesarean delivery for labor arrest (odds ratio, 8.8; 95% confidence interval, 3.6-21.7) and had higher accuracy in predicting cesarean delivery compared with the accuracy of fetal head circumference and obstetrical conjugate alone, with an area under the curve of 0.91 (95% confidence interval, 81.7-99.5; P<.001). A positive correlation between the head circumference/obstetrical conjugate ratio and length of the second stage of labor was found (Pearson coefficient, 0.16; P=.018).
Our study, conducted on an unselected low-risk population, demonstrated that the head circumference/obstetrical conjugate ratio is a reliable antenatal predictor of labor arrest leading to cesarean delivery.
摘要：
背景：劳动逮捕估计约占所有初次剖宫产分娩的三分之一，并且与不良孕产妇和围产期结局的风险增加相关。主要原因之一是产道的大小与胎儿的大小不匹配，一种通常被称为头盆不称的病症。
目的：本研究旨在描述一种新的超声预测因素，即由于怀疑头盆比例不正导致剖宫产而导致的分娩停滞。
方法：这是一项多中心前瞻性研究，于2021年1月至2022年1月在3个产妇单元进行。一系列非连续的单胎妊娠与头端胎儿，胎龄34周+0天或以上，在每个机构的产前诊所就诊的阴道分娩没有禁忌症被认为是合格的。在妊娠34+0到38+0周之间，所有符合条件的患者均接受了产科缀合物的经腹2D超声测量.进入劳动病房后，通过经腹超声在标准经丘脑平面上测量胎儿头围。研究的主要结果是胎儿头围与产科共轭测量之间的比率的准确性（即，头围/产科共轭比）用于预测继发于分娩的剖宫产的发生。次要结局是头围/产科共轭比与产程之间的关系。
结果：共纳入263名女性。在纳入的病例中，7.6%(20/263)因分娩而进行剖宫产，并与更频繁地使用硬膜外镇痛相关(95.0%vs45.7%;P<.001)，较长的第二产程（193[120-240]vs34.0[13.8-66.5]分钟；P=.002），较短的产科缀合物（111[108-114]vs121[116-125]mm；P<.001），头围/产科共轭比较高（3.2[3.2-3.35]vs2.9[2.8-3.0]；P<.001），与阴道分娩相比，出生体重较高（3678[3501-3916]vs3352[3095-3680]g；P=.003）。在逻辑回归分析中，以Z分数表示的头围/产科共轭比率是唯一与因分娩而导致的剖宫产风险独立相关的参数(比值比,8.8；95%置信区间，3.6-21.7），与仅胎儿头围和产科共轭的准确性相比，在预测剖宫产方面具有更高的准确性，曲线下面积为0.91(95%置信区间，81.7-99.5；P<.001）。发现头围/产科共轭比与第二产程长度之间呈正相关（皮尔逊系数，0.16；P=.018）。
结论：我们的研究，在未选择的低风险人群中进行，证明头围/产科共轭比是导致剖宫产的分娩停滞的可靠产前预测指标。
目的：本研究旨在描述一种新的超声预测因素，即由于怀疑头盆比例不正导致剖宫产而导致的分娩停滞。
方法：这是一项多中心前瞻性研究，于2021年1月至2022年1月在3个产妇单元进行。一系列非连续的单胎妊娠与头端胎儿，胎龄34周+0天或以上，在每个机构的产前诊所就诊的阴道分娩没有禁忌症被认为是合格的。在妊娠34+0到38+0周之间，所有符合条件的患者均接受了产科缀合物的经腹2D超声测量.进入劳动病房后，通过经腹超声在标准经丘脑平面上测量胎儿头围。研究的主要结果是胎儿头围与产科共轭测量之间的比率的准确性（即，头围/产科共轭比）用于预测继发于分娩的剖宫产的发生。次要结局是头围/产科共轭比与产程之间的关系。
结果：共纳入263名女性。在纳入的病例中，7.6%(20/263)因分娩而进行剖宫产，并与更频繁地使用硬膜外镇痛相关(95.0%vs45.7%;P<.001)，较长的第二产程（193[120-240]vs34.0[13.8-66.5]分钟；P=.002），较短的产科缀合物（111[108-114]vs121[116-125]mm；P<.001），头围/产科共轭比较高（3.2[3.2-3.35]vs2.9[2.8-3.0]；P<.001），与阴道分娩相比，出生体重较高（3678[3501-3916]vs3352[3095-3680]g；P=.003）。在逻辑回归分析中，以Z分数表示的头围/产科共轭比率是唯一与因分娩而导致的剖宫产风险独立相关的参数(比值比,8.8；95%置信区间，3.6-21.7），与仅胎儿头围和产科共轭的准确性相比，在预测剖宫产方面具有更高的准确性，曲线下面积为0.91(95%置信区间，81.7-99.5；P<.001）。发现头围/产科共轭比与第二产程长度之间呈正相关（皮尔逊系数，0.16；P=.018）。
结论：我们的研究，在未选择的低风险人群中进行，证明头围/产科共轭比是导致剖宫产的分娩停滞的可靠产前预测指标。
