Maternal and Child Health Research Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
Maternal and Child Health Research Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
Am J Obstet Gynecol MFM. 2021 Jan;3(1):100175. doi: 10.1016/j.ajogmf.2020.100175. Epub 2020 Jul 17.
Distinguishing between true and false preterm labor remains a challenge. The shortening in cervical length throughout a gestation has been theorized to be a possible predictor of spontaneous preterm birth. Although there are some studies evaluating cervical length shortening as a predictor of spontaneous preterm birth, it is not known whether the shortening in cervical length from an asymptomatic to symptomatic state, when a patient presents with preterm labor symptoms, is predictive of spontaneous preterm birth.
This study aimed to determine the utility of cervical length shortening from an asymptomatic time point (anatomic ultrasound) to when a patient presents with preterm labor symptoms as a predictor of spontaneous preterm birth.
A prospective cohort study was performed to evaluate the use of transvaginal cervical length assessment in symptomatic women in predicting spontaneous preterm birth from January 2013 to March 2015. Women with singleton gestations who presented to our institution between 22 0/7 weeks and 33 6/7 weeks of gestation with preterm labor symptoms were included in the overall cohort. This was a planned secondary analysis to evaluate the shortening in cervical length from an asymptomatic state (anatomic ultrasound) to a symptomatic state as a predictor of preterm birth. For this analysis, inclusion criteria were known delivery status, cervical length screening performed at anatomic ultrasound, and a valid cervical length measurement at the time of preterm labor symptoms. Women with preterm rupture of membranes, cervical dilation of >2 cm, or moderate to severe bleeding were excluded. Cervical length shortening was defined as a decrease in cervical length of >10 mm from anatomic ultrasound to the time of presentation with preterm labor symptoms. The outcome evaluated was spontaneous preterm birth before 37 weeks of gestation. Chi-square test and receiver operating characteristic curves were used to evaluate the data. Multivariable logistic regression was used to calculate the odds. Test characteristics of cervical length shortening of >10 mm were determined.
A total of 549 women were included in the original cohort, and 277 women were included in this secondary analysis. The overall rate of spontaneous preterm birth was 8.3%. There were 52 women (19%) with cervical length shortening of >10 mm. The rate of spontaneous preterm birth was significantly higher for those with cervical length shortening of >10 mm than those with cervical length shortening of ≤10 mm (21.2% vs 5.3%; P=.001). This higher risk of spontaneous preterm birth remained after adjusting for confounders including maternal age and previous spontaneous preterm birth (adjusted odds ratio, 4.71; 95% confidence interval, 1.84-12.09). Using cervical length shortening of >10 mm as a screening test had a sensitivity of 47.8%, a specificity of 83.9%, a positive predictive value of 21.2%, and a negative predictive value of 94.7%.
In women presenting with preterm labor symptoms, a cervical length that is >10 mm shorter from anatomic ultrasound is associated with an increased risk of spontaneous preterm birth.
区分真假早产仍然是一个挑战。人们认为，妊娠期间宫颈长度的缩短可能是自发性早产的一个预测指标。虽然有一些研究评估了宫颈长度缩短作为自发性早产的预测指标，但尚不清楚当患者出现早产症状时，从无症状状态到有症状状态的宫颈长度缩短是否可以预测自发性早产。
本研究旨在确定从无症状时间点（解剖超声）到出现早产症状时宫颈长度缩短作为自发性早产预测指标的效用。
本研究采用前瞻性队列研究评估了 2013 年 1 月至 2015 年 3 月间我院就诊的 22 0/7 周至 33 6/7 周有早产症状的单胎妊娠妇女中经阴道宫颈长度评估在预测自发性早产中的应用。将有早产症状的单胎妊娠妇女纳入总体队列，这些妇女的妊娠时间在 22 0/7 周至 33 6/7 周之间。这是一项旨在评估从无症状状态（解剖超声）到有症状状态时宫颈长度缩短作为早产预测指标的二次分析。本分析的纳入标准为已知分娩状态、在解剖超声时进行宫颈长度筛查以及在出现早产症状时有有效宫颈长度测量值。排除了有胎膜早破、宫颈扩张>2cm 或中重度出血的患者。宫颈长度缩短定义为从解剖超声到出现早产症状时宫颈长度缩短>10mm。本研究评估的结局为 37 周前自发性早产。采用卡方检验和受试者工作特征曲线来评估数据。采用多变量逻辑回归计算比值比。确定了宫颈长度缩短>10mm的测试特征。
原始队列共纳入 549 例患者，二次分析纳入 277 例患者。自发性早产总发生率为 8.3%。有 52 例（19%）患者的宫颈长度缩短>10mm。与宫颈长度缩短≤10mm的患者相比，宫颈长度缩短>10mm的患者自发性早产发生率显著更高（21.2% vs 5.3%；P=.001）。调整包括母亲年龄和既往自发性早产在内的混杂因素后，这种自发性早产的风险仍然更高（调整后的比值比，4.71；95%置信区间，1.84-12.09）。使用宫颈长度缩短>10mm作为筛查试验，其敏感性为 47.8%，特异性为 83.9%，阳性预测值为 21.2%，阴性预测值为 94.7%。
在出现早产症状的妇女中，与解剖超声相比宫颈长度缩短>10mm与自发性早产风险增加相关。
