足月妊娠低风险初产妇阴道试产失败中转剖宫产预测模型的建立

A model for predicting cesarean delivery in term low-risk primipara after failure of trial of labor

目的建立适用于国内本地区足月妊娠低风险初产妇阴道试产失败中转剖宫产的预测模型。方法回顾性分析2011年1月1日至2017年8月31日苏州大学附属第一医院妇产科所有足月单胎头位低风险初产妇的病例资料,按最终分娩方式分为中转剖宫产组和阴道分娩组。采用t检验、χ^2检验及多因素logistic回归分析进行统计学分析,筛选出阴道试产失败中转剖宫产的影响因素,并建立预测模型。利用受试者工作特性(receiver operating characteristic,ROC)曲线和Hosmer-Lemeshow goodness-of-fit检验等对模型预测性能进行评估。利用R语言基于风险预测模型构建列线图。结果(1)共纳入6551例初产妇,中转剖宫产组576例(8.8%),阴道分娩组5975例(91.2%)。(2)中转剖宫产组产妇的年龄、孕前体重指数、孕期增重、分娩时妊娠天数均高于阴道分娩组[分别为(27.5±3.1)与(26.8±3.0)岁,t=-4.963;(21.5±2.6)与(20.8±2.5)kg/m^2,t=-6.743;(14.8±4.2)与(14.1±4.2)kg,t=-3.446;(282±7)与(278±7)d,t=-10.499;P值均<0.01],身高低于阴道分娩组[(159.5±4.2)与(161.7±4.6)cm,t=11.548,P<0.01],胎膜早破发生率高于阴道分娩组[26.4%(152/576)与20.7%(1238/5975),χ^2=10.101,P<0.01],使用催产素、人工破膜、水囊、欣普贝生引产比例均高于阴道分娩组[分别为26.4%(152/576)与16.3%(976/5975)、46.5%(268/576)与36.6%(2189/5975)、2.6%(15/576)与1.1%(65/5975)、4.7%(27/576)与2.5%(149/5975),χ^2=134.918,P<0.01],羊水污染Ⅰ、Ⅱ及Ⅲ/血性羊水比例高于阴道分娩组[分别为5.2%(30/576)与3.5%(209/5975)、5.7%(33/576)与2.5%(150/5975)、13.7%(79/576)与1.8%(105/5975),χ^2=307.664,P<0.01],男性胎儿比例[58.0%(334/576)与49.1%(2934/5975),χ^2=16.576,P<0.01]和新生儿出生体重均高于阴道分娩组[(3528±389)与(3344±368)g,t=-11.431,P<0.01]。(3)多因素logistic回归分析结果显示,初产妇的年龄越大、身高越矮、孕前体重指数越大、孕期增重越多、妊娠时间越长、胎膜早破、使用催产素引产、人工破膜、水囊引产、欣普贝生引产、羊水污染及男性胎儿是中转剖宫产的独立影响因素。并根据是否纳入胎儿性别因素建立了2个中转剖宫产的预测模型及列线图。(4)未纳入胎儿性别建立的模型,其ROC曲线下面积为0.774(95%CI:0.763~0.784),最佳临界风险为>8.7%,此时灵敏度为0.707,特异度为0.706;如果将胎儿性别纳入建立的模型,其ROC曲线下面积为0.782(95%CI:0.771~0.791),当最佳预测概率>7.4%时,灵敏度为0.785,特异度为0.645。通过Hosmer-Lemeshow goodness-of-fit检验,两模型的拟合程度均较好(P值均>0.05)。两模型的内部验证结果提示预测的中转剖宫产的概率与实际观察到的概率存在较好的一致性。结论联合上述因素建立的足月单胎头位低风险初产妇阴道试产失败中转剖宫产的风险预测模型预测效能较好,准确率较高,可为临床医生指导产妇选择恰当的分娩方式提供参考,以改善母婴结局。

Objective To establish a model for predicting cesarean delivery after failure of trial of labor among low-risk term primipara.Methods This study retrospectively analyzed the clinical data of low-risk primiparas,with singleton cephalic full-term fetus,who delivered in the Department of Obstetrics and Gynecology of the First Affiliated Hospital of Soochow University from January 1,2011 to August 31,2017.Women experienced cesarean delivery(CS)following failed trial of labor were grouped as CS group,while those successfully delivered normally as vaginal delivery group(VD group).Chi-square test,t-test and multivariate logistic regression analysis were used for statistical analysis.Influencing factors of CS after a failed trial of labor were screened to establish the prediction model.The area under the receiver operating characteristic curve(AUC)and Hosmer-Lemeshow goodness-of-fit test were used to assess the performance of the model.A nomogram was established using R programming language based on the predictive model.Results(1)This study recruited 6551 subjects and among them,576(8.8%)women experienced CS after a failed trial of labor and the rest 5975(91.2%)delivered vaginally.(2)The women in CS group were older[(27.5±3.1)vs(26.8±3.0)years,t=-4.963,P<0.01]and shorter in height[(159.5±4.2)vs(161.7±4.6)cm,t=11.548,P<0.01],had higher pre-pregnancy body mass index(BMI)[(21.5±2.6)vs(20.8±2.5)kg/m^2,t=-6.743,P<0.01]and higher weight gain during pregnancy[(14.8±4.2)vs(14.1±4.2)kg,t=-3.446,P<0.01]and delivered later[(282±7)vs(278±7)d,t=-10.499,P<0.01]compared with those in VD group.The incidence of premature rupture of membranes(PROM)[26.4%(152/576)vs 20.7%(1238/5975),χ^2=10.101,P<0.01],labor induction[oxytocin:26.4%(152/576)vs 16.3%(976/5975),artificial rupture of membranes:46.5%(268/576)vs 36.6%(2189/5975),application of cervical dilator balloon:2.6%(15/576)vs 1.1%(65/5975)and Propess:4.7%(27/576)vs 2.5%(149/5975),χ^2=134.918,P<0.01],and the proportion of cases with meconium-stained amniotic fluid[Ⅰ:5.2%(30/576)vs 3.5%(209/5975),Ⅱ:5.7%(33/576)vs 2.5%(150/5975),Ⅲ/bloody:13.7%(79/576)vs 1.8%(105/5975),χ^2=307.664,P<0.01]were all higher in CS group than in VD group.There were more male infants[58.0%(334/576)vs 49.1%(2934/5975),χ^2=16.576,P<0.01]and higher neonatal birth weight[(3528±389)vs(3344±368)g,t=-11.431,P<0.01]in the CS group as well.(3)Multivariate logistic regression analysis showed that maternal age and height,pre-pregnancy BMI,weight gain during pregnancy,gestational age at delivery,PROM,labor induction with oxytocin,artificial rupture of membrane,application of cervical dilator balloon and Propess,meconium-stained amniotic fluid,and fetal gender were all independent factors for CS.Two prediction models and nomograms were established according to fetal gender was involved or not.(4)The AUC of the prediction model not involving fetal gender was 0.774(95%CI:0.763-0.784)and the cut-off value was>8.7%with the sensitivity and specificity of 0.707 and 0.706,while that involving fetal gender was 0.782(95%CI:0.771-0.791)with the sensitivity and specificity of 0.785 and 0.645,respectively,when the cut-off value was>7.4%.The Hosmer-Lemeshow goodness-of-fit test showed that the two models fitted well(both P>0.05).Results of the internal validation using Bootstrap method indicated that the CS rates predicted by both models were consistent with the real data.Conclusions The established models could effectively and accurately predict CS in term,singleton,cephalic,and low-risk primipara after failure of trial of labor,which might be a tool for clinicians to inform pregnant women to choose an appropriate delivery mode,thus improving maternal and infant outcomes.