Relations between fetal brain-sparing circulation, oxytocin challenge test, mode of delivery and fetal outcome in growth-restricted term fetuses

摘要

Objective. The study was designed as a prospective non-interventional, observational study to elucidate the potential value of fetal middle cerebral artery Doppler velocimetry to identify brain-sparing flow in a surveillance program for suspected intrauterine growth restriction (IUGR). Material and methods. The study was carried out at Skane University Hospital, Malmo, Sweden. One hundred and twenty-six single pregnancies suspected of IUGR at >36 gestational weeks were assessed. The main outcome measures were positiveegative oxytocin challenge test (OCT) and cesarean/vaginal delivery. The pregnancies were managed with ultrasound fetom-etry, uterine and umbilical artery Doppler flow velocimetry, nonstress test, and an OCT to decide the optimal time and mode of delivery. Cases with a positive OCT were promptly delivered by cesarean section, whereas negative cases were allowed a trial of labor. Middle cerebral artery Doppler flow velocimetry results were blinded to the managing obstetricians. Brain-sparing flow was denned as a middle cerebral artery-to-umbilical artery pulsatility index ratio of < 1.08. Nonparametric statistics with significance set at p < 0.05 were used, and Cohen's kappa coefficient was calculated for congruence of brain-sparing flow with OCT and mode of delivery, respectively. Results. The positive predictive value and sensitivity figures of brain-sparing flow to indicate a positive OCT and cesarean delivery were 33-63%. The inter-rater reliability of brain-sparing flow vs. positive OCT showed a kappa coefficient of 0.19, and brain-sparing flow vs. cesarean section among OCT-negative cases a kappa coefficient of 0.23. Conclusion. Fetal brain-sparing flow is a poor predictor of a positive OCT, and of cesarean section in OCT-negative cases.