晚孕期脐带绕颈胎儿大脑中动脉和脐动脉阻力指标与比值预测胎儿窘迫

Prediction of fetal hypoxia by measuring middle cerebral and umbilical artery resistance index in fetuses with umbilical cord around the neck in late pregnancy

目的探讨妊娠晚期脐带绕颈胎儿大脑中动脉（MCA）和脐动脉（UA）阻力指标与比值预测宫内缺氧的早期诊断价值。方法运用彩色多谱勒超声检测80例38--40孕周的正常胎儿和88例脐带绕颈胎儿的MCA和UA搏动指数（PI）、阻力指数（RI）、收缩期峰值流速与舒张末期流速比值（S／D），然后计算其阻力指标与比值结果，用测得的正常值对脐带绕颈胎儿进行宫内缺氧的判断，将结果进行诊断试验评价。组间比较采用完全随机的方差分析。结果各组间比较胎儿MCA和UA阻力指标比值有非常显著性差异（P〈0．01），正常组与绕颈1周组阻力指标比较无差异（P〉0．05）；与绕颈2周及以上组比较有非常显著性差异（P〈0．01）。绕颈1周组与绕颈2周及以上组比较也有显著性差异（P〈0．05）。用UA、MCA阻力指标与阻力指标比值的正常参考值，预测脐带绕颈胎儿缺氧的敏感性和特异性分别为43％、85％、92％，83％、89％、100％。结论MCA与UA阻力指标比值预测脐带绕颈胎儿宫内缺氧优于其阻力指标，可早期发现脐带绕颈胎儿宫内缺氧状态，在胎儿窘迫发生前作出诊断，具有重要的临床价值。

Objective To investigate the value of middle cerebral artery （MCA） and umbilical artery （UA） resistance index in predicting fetal hypoxia in fetuses with umbilical cord around the neck in late pregnancy. Methods Eighty normal fetuses between 38 and 40 weeks of gestation and 88 fetuses with umbilical cord around neck were measured for MCA and UA pulsatility index （PI）, resistance index （RI） and the peak-systolic/diastolic ratio （S/D） by means of color Doppler ultrasonography, and the resistance index ratio was calculated. Fetuses with umbilical cord around neck were estimated according to the measured normograms for the presence of fetal hypoxia, and the results were evaluated by diagnostic test. Results Significant differences were found in MCA and UA resistance index ratio between the groups （P〈0.01）. There was no significant difference in the resistance index ratio between the normal group and around the neck （one round） group （P〉0.05）, but significant difference was found between normal group and around the neck （two rounds and more） group （P〈0.01）, and between the two arounds and one round groups （P〈0.05）. The sensitivity and specificity of MCA and UA resistance index and resistance index ratio in predicting fetal hypoxia of fetuses with umbilical cord around neck was 43%, 85%, 92%, 83%, 89%, and 100%, respectively. Conclusion MCA and UA resistance index ratio is a better indicator than its resistance index in predicting fetal hypoxia of fetuses with umbilical cord around neck, and may help in early detection of fetal hypoxia for a diagnosis before fetal distress.