Diagnostic Value In Predicting Fetal Hypoxia By Monitoring Hemodynamic Parameters Of Major Arteries In Fetuses With Nuchal Cord Before Delivery

Objective:To investigate the diagnostic value of color doppler ultrasound in predicting fetal hypoxia by monitoring the hemodynamic parameters of the middle cerebral artery (MCA), renal artery(RA) and umbilical artery(UA) in fetuses with umbilical cord around the neck before delivery, and choose the most valuable hemodynamic parameter for predicting fetal hypoxia, in order to provide evidences for choosing appropriate delivery time and mode, and to prevent undesirable pregnant outcomes and reduce the rate of blind cesarean section.Methods:Nity-nine women of singleton and full-term pregnancy before delivery who did antenatal examination in department of gynecology and obstetrics at The second Hospital of Shandong University between March,2011and November,2011were choosed as study objects, whose fetuses were diagnosed with umbilical cord around the neck by color Doppler ultrasound. The hemodynamic parameters of middle cerebral artery (MCA), renal artery (RA) and umbilical artery (UA) of all fetuses were prospectively obtained through Doppler flow velocimetry, including systolic peak velocity/end diastolic velocity (S/D), pulsatility index (PI) and resistance index (RI). Then the hemodynamic parameters ratioes of arteries were calculated, including PIUA/PIMCA, RIUA/RIMCA, S/DUA/S/DMCA. PIRA/PIMCA, RIRA/RIMCA, and S/DRA/S/DMCA. Followed up and recorded changes of fetal heart rate and property of amniotic fluid during delivery, laps of umbilical cord around neck, neonatal Apgar score. According to the delivery outcome of whether fetal hypoxia occurred or not, the research objects were divided into two groups:normal group and hypoxia group. All the hemodynamic parameters of the two groups were analyzed by SPSS13.0system with methods of independent-samples T-test.95%confidence interval were calculated. Finaly, we made diagnostic test evaluation of the hemodynamic parameters in predicting fetal hypoxia, calculated their sensitivity (true positive number/true positive number+false negative number), specificity(true negative number/true negative number+false positive number), Youden index (specificity+sensitivity-1), and selected the most valuable hemodynamic parameter for predicting fetal hypoxia in full-term fetuses with umbilical cord around the neck before delivery.Results:1. S/D value and PI value of RA in hypoxia group were significantly higher than normal group (S/DRA:P<0.05, PIRA:P<0.01). RI value of RA and hemodynamic parameters of UA and MCA had no significant differences between the two groups (P>0.05)2. S/D value ratio between RA and MCA, PI value ratio between RA and MCA in hypoxia group were significantly higher than normal group (P<0.05). RI value ratio between RA and MCA and the hemodynamic parameters ratios between UA and MCA (PIUR/PIMCA, RIUA/RIMCA,S/DUA/S/DMCA) had no significant difference between the two groups (P>0.05).3. The sensitivity of using S/D value(≥4.9), PI value(≥1.9) of renal artery to predict the occurrence of fetal hypoxia were respectively70.7%,51.2%; and the specificity were respectively74.2%,83.9%; and the Youden index were respectively0.45,0.35. When combined the two hemodynamic parameters, the sensitivity became46.3%, the specificity became87.1%, and the Youden index became0.33.4. After birth, it was confirmed that there were92fetuses with nuchal cord. The diagnostic rate of CDFI for nuchal cord was92.9%. Of the92fetuses,51fetuses were diagnosed with hypoxia by clinical manifestation in the process of delivery. The incidence of fetal hypoxia in fetuses with nuchal cord was55.43%.Conclusion:1. The hemodynamics of renal artery in full-term fetuses with umbilical cord around the neck before delivery has changed, which changes earlier than the hemodynamics of the middle cerebral artery and umbilical artery, and the abnormal fetal heart rate monitoring. S/D value and PI value of renal artery in predicting fetal hypoxia have certain clinical diagnosis value, especially S/D value of renal artery.2. Although the fetal heart rates of fetuses with umbilical cord around the neck are normal before delivery, who have fetal hypoxia during delivery, the fetuses may be in early stage of intrauterine hypoxia, and the blood flow have already distributed to start "the brain protection effect"3. The sensitivity and specificity of the major arteries (MCA,RA,UA)in full-term fetuses with umbilical cord around the neck before delivery in predicting fetal hypoxia are not ideal. It is difficult and time-consuming to monitor the hemodynamic parameters, and there are many objective factors influenting the results. It is difficult to popularize widely in clinical, so we need to look futher for a more convenient and practical monitoring method.