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

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.