胎儿脐带绕颈时静脉导管及大脑中动脉的血流变化

目的探讨胎儿脐带绕颈时静脉导管、大脑中动脉的血流变化。方法应用彩色多普勒超声检查288例28~40孕周胎儿的静脉导管、大脑中动脉的血流波形并测定血流参数,其中无脐带绕颈125例,绕颈1周136例、2周24例、3周及3周以上3例,测定静脉导管的前负荷指数（PLI）、搏动指数（PIV）、S/a值、静脉导管分流率（QDV/QUV）,大脑中动脉的阻力指数（RI）、搏动指数（PI）、胎儿脐动脉收缩压与舒张压比值（S/D）。结合胎儿心电监护（ECG）,比较静脉导管及大脑中动脉各血流阻力指标预测胎儿宫内缺氧的敏感性、特异性。结果脐带绕颈组比正常对照组静脉导管的PLI、PIV、S/a值增高,差异有统计学意义（P〈0.05）,ODV/QUV增加,差异无统计学意义（P〉0.05）,大脑中动脉的RI、PI降低,差异有统计学意义（P〈0.05）,S/D值降低,差异无统计学意义（P〉0.05）。静脉导管的PLI、PIV、S/a值均可对胎儿宫内缺氧作出预测,ROC曲线下面积分别为0.776、0.784、0.776。大脑中动脉各血流阻力指标诊断价值不大。结论脐带绕颈组比正常组静脉导管的血流阻力指标增加,大脑中动脉血流阻力指标降低。在预测胎儿宫内缺氧中,静脉导管比大脑中动脉诊断价值高。静脉导管血流阻力指标的测定可以用来判断脐带绕颈的松紧性。

Blood flow changes of ductus venosus and middle cerebral artery in fetus with cord around neck

Objective To explore the changes of the resistant parameters of ductus venosus（DV） and middle cerebral artery（MCA） in fetus with cord around neck.Methods Among 288 cases of fetus（28-40 gestational weeks）,the waveform and resistant parameters of DV and MCA including preload index of DV（DV-PLI）,pulsatility index of DV（DV-PIV）,DV-S/a,QDV/QUV,resistance index of MCA（MCA-RI）,pulsatility index of MCA（MCA-PI）,peak-systolic/diastolic ratio of MCA（MCA-S/D） were analyzed with color Doppler ultrasound,125 cases were normal and 163 fetuses with cord around neck,among which 136 cases of fetuses with one nuchal loop,24 cases with two loops,3 cases with three loops.The sensitivity and specificity of the resistant parameters of DV′s predicting fetal distress were compared with MCA,combined with the results of ECG.Results The resistant parameters of DV,including PLI,PIV,S/a were higher in the study group than those in the control group,there were significant differences（P 0.05）.QDV/QUV was also higher but there was no statistical difference（P 0.05）.While MCA-PI and MCA-RI were lower in the study group than those in the control group（P 0.05）,MCA-S/D was lower（P 0.05）.DV-PLI,DV-PIV,DV-S/a could predict fetal distress.The area of receiver-operator characteristics curve（ROC curve） of DV-PLI,DV-PIV,DV-S/a were 0.776,0.784,0.776.The resistant parameters of MCA in fetus didn′t have much value in diagnosis.Conclusion The resistant parameters of DV are higher in the study group than those in the control group,while the resistant parameters of MCA are lower in the study group than those in the control group.In prediction of fetal distress,DV plays a much more significant diagnostic role.We can predict whether the nuchal cord is loose or tight by measuring the resistant parameters of DV.