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A combined sector and pulsed d.oppler system was used to measure blood flow velocity wave-forms n the fetal internal carotid artery and umbilical artery in 104 normal pregnancies and 52 growth - retarded pregnancies. For the analysis of the blood flow velocity waveform, A/B ratio ant. Resistance index(RI) were employed. The ratio between A/B ratio of umbilical artery and A/B ratio of internal carotid artery was calculated(UAB/CAB ratio). And, the ratio between RI of umbilical artery and RI of internal carotid artery was also calculated(URI/CRI ratio). Before term(< 38 weeks gestation),both the UAB/CAB ratio and URI/CRI ratio were significantly higer n growth-retarded pregnancies than in normal pregnancies. As gestation advanced, UAB/CAB ratio increased but URI/CRI ratio remained relatively constant during normal pregnancy. But UA.I/CAB ratio and URI/CRI ratio decreased with increasing gestation in growth -retarded p-regnant ies. If we defined the velocity waveform to be abnormal, when the UAB/CAB ratio or URI/CRI ratio were above mean + 2SD of normal pregnancy, the sensitivity of UAB/CAB ratio in predictiig growth- retarded fetus was 35.9% and specificity was 95.9%. Positive and negative predicti´i,e values of UAB/CAB ratio in predicting growth -retarded fetus were 84.8% and 70.2% respecti,yely. Those values of URI/CRI ratio in predicting growth-retarded fetus were 34.6%, 95.9%, 84.4% and 69.8% respectively.
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