Objective: To investigate the feasibility of predicting the risk of spontaneous preterm birth in singleton pregnancy women with low risk of preterm birth by transabdominal-transvaginal ultrasound cervical length sequential screening in the second trimester. Methods: This prospective longitudinal cohort study included singleton pregnant women at 11-13+6 gestational weeks who were admitted to Nanjing Drum Tower Hospital from January 2023 to September 2023. Transabdominal and transvaginal cervical lengths were measured during the mid-trimester fetal ultrasound scan at 18-24 weeks, and pregnancy outcomes were obtained after delivery. A short cervix was defined as a transvaginal cervical length of ≤25 mm, and the outcomes were defined as spontaneous preterm birth occurs between 20 and 36+6 weeks and extremely preterm birth before 32 weeks. The area under the receiver operating characteristic (ROC) curve was used to evaluate the effectiveness of predicting spontaneous preterm birth by transabdominal and transvaginal cervix length, as well as the effectiveness of predicting short cervix by transabdominal cervical length. The relationship between transabdominal and transvaginal cervical length was evaluated using a scatter plot. Results: A total of 562 cases were included in this study, comprising 33 cases of spontaneous preterm birth (7 cases occurring before 32 weeks) and 529 cases of term birth. (1) Compared to the term birth group, transabdominal cervical length (median: 37.6 vs 33.2 mm; Z=-3.838, P<0.001) and transvaginal cervical length (median: 34.0 vs 29.9 mm, Z=-3.030, P=0.002) in the spontaneous preterm birth group were significantly shorter. (2) The areas under the ROC curve for predicting spontaneous preterm birth by transabdominal and transvaginal cervical length were 0.699 (95%CI: 0.588-0.809) and 0.657 (95%CI: 0.540-0.774), respectively. The sensitivity, specificity and positive predictive value of transvaginal cervical length Conclusions: In singleton pregnancy women with low risk of preterm birth, transabdominal-transvaginal cervical length sequential screening can reduce unnecessary transvaginal ultrasounds by approximately 41% without missing the diagnosis of pregnant women with a short cervix. This method also enhances the effectiveness of transvaginal cervical length to spontaneous preterm birth.
目的： 探讨妊娠中期筛查胎儿结构时应用经腹-经阴道超声序贯法预测早产低风险单胎妊娠孕妇发生自发性早产的价值。 方法： 本研究采用前瞻性纵向队列，纳入2023年1—9月在南京大学医学院附属鼓楼医院就诊的妊娠11~13+6周的单胎妊娠孕妇，于妊娠18~24周行妊娠中期筛查胎儿结构时应用经腹超声（TAU）测量的子宫颈长度初步筛查短子宫颈，对可疑者再行经阴道超声（TVU）检查（即经腹-经阴道超声序贯法），并在分娩后获得妊娠结局，短子宫颈定义为TVU子宫颈长度≤25 mm，终点观察指标为发生于妊娠20~36+6周的自发性早产和极早产（妊娠32周前分娩）。采用受试者工作特征（ROC）曲线下面积（AUC）评估TAU和TVU子宫颈长度预测自发性早产的效能，以及TAU子宫颈长度预测短子宫颈的效能，散点图评估TAU与TVU子宫颈长度的关系。 结果： 最终562例单胎妊娠孕妇纳入本研究，包括自发性早产33例（其中极早产7例），足月分娩529例。（1）与足月分娩孕妇比较，自发性早产孕妇的TVU子宫颈长度（中位数分别为37.6、33.2 mm）、TAU子宫颈长度（中位数分别为34.0、29.9 mm）均较短，分别比较，差异均有统计学意义（P均<0.05）。（2）TVU子宫颈长度和TAU子宫颈长度预测早产，ROC曲线的AUC分别为0.699（95%CI为0.588~0.809）和0.657（95%CI为0.540~0.774）。TVU子宫颈长度≤25 mm预测自发性早产的敏感度为30.3%，特异度为98.9%，阳性预测值为62.5%，TAU子宫颈长度≤35 mm预测自发性早产的敏感度为66.7%，特异度为40.4%，阳性预测值为6.7%；TVU子宫颈长度≤25 mm预测极早产的敏感度为71.4%，特异度为98.0%，阳性预测值为31.3%，TAU子宫颈长度≤35 mm预测极早产的敏感度为85.7%，特异度为40.4%，阳性预测值为1.8%。（3）TAU子宫颈长度与TVU子宫颈长度之间呈显著正相关（r=0.622，P<0.001）。所有TVU子宫颈长度≤25 mm的孕妇，TAU子宫颈长度均<35 mm。仅在TAU子宫颈长度≤35 mm的孕妇中行TVU测量子宫颈长度预测自发性早产，敏感度为45.5%，预测极早产敏感度为83.3%。 结论： 在早产低风险的单胎妊娠孕妇中，对TAU子宫颈长度≤35 mm者再行TVU测量子宫颈长度可在几乎不漏诊短子宫颈孕妇的情况下，减少41%不必要的TVU检查，提高了TVU筛查子宫颈长度预测早产的效能。.