正常胎儿脐静脉血流率与脐动脉搏动指数比值的研究

Study of the ratio of normal fetal umbilical venous blood flow rate to umbilical artery pulsatility index

目的建立胎儿脐静脉血流率与脐动脉搏动指数比值(VAI)的正常参考值范围。方法随机选取2018年10月至2020年12月在广西壮族自治区妇幼保健院行产前检查并分娩的816例正常胎儿。通过测量胎儿双顶径、头围、腹围及股骨长获取胎儿体重;测量腹内段脐静脉血流量(Quv);获取羊水中游离段脐动脉血流搏动指数(UA-PI);将Quv按照胎儿体型标准化,计算脐静脉血流率(nQuv)、VAI。采用相关性分析法分析Quv、nQuv、UA-PI、VAI与胎儿孕周的相关性;统计VAI以±s表示,取95%参考值上限及5%参考值下限作为VAI增高和减低的标准。将VAI低于正常值参考值5%的26例胎儿及VAI高于正常值参考值95%的20例胎儿纳入病例组。结果①胎儿Quv与孕周呈正相关(r=0.893,P<0.001),nQuv、UA-PI与孕周呈负相关(r=-0.552、-0.827,均P<0.001),VAI与孕周无明显相关性(r=0.000,P=0.758)。②VAI均值、标准差、5%参考值下限、95%参考值上限分别为195.81、55.61、105.95、293.33。③VAI异常病例组中26例VAI减低(孕妇高血压疾病16例,并发重度子痫前期13例,并发子痫前期1例,脐带扭转40圈1例,死胎3例,早产16例,新生儿低出生体重19例,1 min Apgar评分≤7分4例,脐动脉血pH<7.2者6例,孕期母体胎儿及随访新生儿均无异常1例);20例VAI增高(胎儿重型α-地中海贫血10例,地中海贫血2例,骶尾部畸胎瘤1例,门体静脉分流1例,胎盘绒毛膜血管瘤3例,孕期母体胎儿及随访新生儿均无异常3例)。结论胎儿VAI的测量、计算简单易行,作为一个综合指标在中晚孕期保持恒定,便于异常胎儿的追踪观察,具有潜在的临床应用价值。

Objective To establish the normal reference range of the ratio of fetal umbilical venous flow rate to umbilical artery pulsatility index(VAI).Methods A total of 816 normal fetuses underwent prenatal examination and delivery were randomly selected from October 2018 to December 2020 in Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region.Fetal weight was obtained by measuring fetal biparietal diameter,head circumference,abdominal circumference,and femoral length.Umbilical venous flow(Quv)was measured.Umbilical artery pulsatility index(UA-PI)was obtained in the free segment of amniotic fluid.Quv was standardized according to fetal size to calculate the umbilical venous flow rate(nQuv)and VAI.The association between Quv,nQuv,UA-PI,VAI and the fetal gestational week were analyzed using correlation analysis.VAI was presented as±s,the upper limit of 95%reference value and the lower limit of 5%reference value were taken as the standards of VAI increase and decrease,respectively.Twenty-six fetuses whose VAI were lower than limit of 5%and 20 fetuse whose VAI were than limit of 95%were chosed as the case group.Results①Fetal Quv was positively correlated with gestational week(r=0.893,P<0.001),nQuv and UA-PI were negatively correlated with gestational week(r=-0.552,-0.827;all P<0.001),and VAI had no significant correlation with gestational week(r=0.000,P=0.758);②The mean,standard deviation,lower 5%reference value,and upper 95%reference value of VAI were 195.81,55.61,105.95,and 293.33,respectively;③In the cases with abnormal VAI,26 fetuses with reduced VAI,of whom there were 16 cases of maternal hypertension,and 13 cases complicated by severe preeclampsia;1 case with 40 turns of umbilical cord torsion,3 cases of stillbirth,16 cases of preterm delivery,19 cases of low neonatal birth body weight,4 cases of 1-min Apgar score≤7,6 cases of umbilical artery blood pH<7.2,and 1 case without abnormalities in fetus during pregnancy and follow-up newborn.Among the 20 fetuses with increased VAI,there were 10 cases of fetal severe thalassemia,2 cases of thalassemia,1 case of sacrococcygeal teratoma,1 case of portal venous shunt,3 cases of placental chorioangioma,and 3 cases without abnormalities in fetus during pregnancy and follow-up newborn.Conclusions The measurement and calculation of fetal VAI is simple and easy to perform.As a comprehensive index,fetal VAI remains constant in mid and late pregnancy,facilitates the follow-up of abnormal fetuses,and has potential clinical application.