Ultrasound measurement of fetal blood flow in predicting fetal outcome.

The efficacy of fetal blood flow assessment in predicting fetal outcome was evaluated in 159 pregnancies suspected of intrauterine growth retardation (IUGR). Blood flow in the fetal aorta and umbilical vein was measured with imaging and pulsed Doppler ultrasound. Volume blood flow values and variables describing the waveform of the maximum aortic blood velocity were checked for relations to subsequent fetal outcome. A new semi-quantitative velocity waveform variable, blood flow class (BFC), was designed and tested. The occurrence of IUGR, imminent fetal distress, a low Apgar score at 1 and 5 min, and a low pH in the umbilical artery and vein were adopted to characterize fetal outcome. Receiver operating characteristic curves were used to demonstrate the sensitivity and false positive rate, and the Cohen's Kappa index was used to compare the predictive capacity of the various blood flow variables. BFC, describing the blood velocity waveform with emphasis on its end-diastolic part, was found to be the most powerful marker of imminent fetal asphyxia (Kappa = 0.66) and of intrauterine growth retardation (Kappa = 0.48).