外倒转术成功的影响因素及其临床意义

Factors influencing success of external cephalic version and their clinical significance

目的探讨外倒转术(external cephalic version,ECV)成功的影响因素并根据影响因素建立术前评分表,以期对拟行ECV的孕妇进行分层管理。方法前瞻性纳入2017年1月1日至2019年12月31日在福建省妇幼保健院非麻醉下行ECV的单胎妊娠孕妇。采用单因素(两独立样本t检验、Mann-WhitneyU检验和χ^(2)检验)及多因素logistic回归分析影响ECV成功的临床特征,采用受试者工作特征(receiver operating characteristic,ROC)曲线计算计量变量的截断值,转换成二分类变量,根据多因素logistic回归分析的回归系数对自变量进行评分,建立术前评分表;采用ROC曲线计算评分表的截断值,根据截断值将研究对象分为低、高分组,采用曲线下面积评估评分表及分组预测ECV成功的效能,比较高分组和低分组ECV成功率、难易程度和分娩方式等。结果研究期间符合纳入标准的孕妇共1 338例,排除885例后,165例拒绝ECV选择直接剖宫产,27例ECV前自发转为头位故取消ECV,最后261例孕妇接受ECV,纳入分析。ECV成功202例,失败59例。(1)非麻醉状态下ECV成功的有利因素有:胎臀与坐骨棘距离<-3.5 cm(OR=0.177,95%CI:0.071~0.438,P=0.009)、宫高与胎臀高低之和<30.25 cm(OR=0.225,95%CI:0.094~0.537,P=0.001)、羊水指数≥12 cm(OR=0.399,95%CI:0.164~0.969,P=0.042)、术者能单手握持胎头或胎臀(OR=0.241,95%CI:0.098~0.589,P=0.002;OR =0.219,95%CI:0.087~0.546,P=0.001)、胎头位于母亲右上腹(OR=0.184,95%CI:0.059~0.568,P=0.003)或左上腹(OR=0.253,95%CI:0.084~0.760,P=0.014)。(2)术前评分预测ECV成功的ROC曲线下面积为0.881(95%CI:0.821~0.941),截断值为5.5,据此将研究对象分为低分组(0~5分)和高分组(6~11分)。分组预测ECV成功的ROC曲线下面积为0.843(95%CI:0.774~0.912);高分组ECV持续时间短[2.0 min(0.5~10.0 min)与10.0 min(0.9~25.8 min),Z=-6.83,P<0.001],操作次数少[1.0次(1.0~4.0次)与3.0次(1.0~5.0次),Z=-8.41,P<0.001],成功率高[92.7%(190/205)与21.4%(12/56),χ^(2)=127.64,P<0.001],术后经阴道分娩率高[75.4%(147/195)与18.5%(10/54)]而剖宫产率低[24.6%(48/195)与81.5%(44/54)](χ^(2)=58.70,P<0.001)。结论胎臀与坐骨棘距离、宫高与胎臀高低之和、羊水指数≥12 cm、术者能单手握持胎头或胎臀以及胎头位于母亲右上腹或左上腹是ECV成功的影响因素,根据这些影响因素建立的评分表可个体化评估ECV的难易度、成功率、术后阴道分娩率等,为临床分层管理提供参考。

Objective To analyze the factors influencing the success rate of external cephalic version(ECV)and to create a preoperative scoring scale for stratified management of pregnant women who were preparing for ECV.Methods This prospective study was conducted on singleton pregnant women who underwent ECV without anesthesia in Fujian Maternity and Child Health Hospital from January 1,2017,to December 31,2019.Univariate(two independent samples t-test,Mann-Whitney U test,and Chi-square test)and multivariate logistic regression were used to screen the clinical characteristics affecting the success of ECV,and receiver operating characteristic(ROC)curve was used to determine the cut-off value and convert quantitative variables into dichotomous variables.The independent variables were scored according to the regression coefficient in multivariate logistic regression analysis,and then a preoperative scoring scale was created.The ROC curve was used to calculate the cut-off value for the scoring scale.The subjects were divided into low and high score groups according to the cut-off value.The area under the ROC curve was used for evaluating the effectiveness of the scale in predicting the success of ECV.The success rate of ECV,difficulty of the operation and mode of delivery were compared between the two groups.Results A total of 1338 pregnant women met the inclusion criteria during the study period.After the exclusion of 885 women,165 refused ECV in favor of direct cesarean section,27 spontaneously converted to cephalic position before ECV,261 who voluntarily accepted ECV were finally enrolled.ECV succeeded in 202 cases and failed in 59.(1)Favorable factors for ECV without anesthesia were the distance between the fetal breech and ischial spine<-3.5 cm(OR=0.177,95%CI:0.071-0.438,P=0.009),the sum of the fundal height and the station of the fetal breech based on the ischial spine<30.25 cm(OR=0.225,95%CI:0.094-0.537,P=0.001),amniotic fluid index≥12 cm(OR=0.399,95%CI:0.164-0.969,P=0.042),the surgeon's ability to hold the fetal head or breech with one hand(OR=0.241,95%CI:0.098-0.589,P=0.002;OR=0.219,95%CI:0.087-0.546,P=0.001),and the fetal head located on the right or left upper abdomen of the mother(OR=0.184,95%CI:0.059-0.568,P=0.003;OR=0.253,95%CI:0.084-0.760,P=0.014).(2)The area under the ROC curve of the preoperative score for predicting the success of ECV was 0.881(95%CI:0.821-0.941)and the cut-off value was 5.5.The subjects were divided into low(0-5 scores)and high(6-11 scores)score groups and the area under the ROC curve for predicting the success of ECV by grouping was 0.843(95%CI:0.774-0.912).Compared with the low score group,the high score group had a shorter ECV duration[2.0 min(0.5-10.0 min)vs 10.0 min(0.9-25.8 min),Z=-6.83,P<0.001],less attempts[1.0 times(1.0-4.0 times)vs 3.0 times(1.0-5.0 times),Z=-8.41,P<0.001],higher success rate[92.7%(190/205)vs 21.4%(12/56),χ^(2)=127.64,P<0.001],higher rate of vaginal birth[75.4%(147/195)vs 18.5%(10/54)]and lower cesarean section rate[24.6%(48/195)vs 81.5%(44/54)](χ^(2)=58.70,P<0.001).Conclusions Preoperative scoring based on the factors influencing the success rate of ECV(the distance between the fetal breech and ischial spine,the sum of the fundal height and the station of the fetal breech based on the ischial spine<30.25 cm,amniotic fluid index≥12 cm,the surgeon's ability to hold the fetal head or breech with one hand,and the fetal head locating on the right or left upper abdomen of the mother)is conducive to the individualized evaluation of the difficulty and the success rate of ECV as well as the success rate of vaginal delivery after ECV,which can provide a reference for clinical stratified management of ECV patients.