The objectives of this study were to characterize spiral artery flow velocity waveforms in normal pregnancies and pregnancies complicated by pregnancy-induced hypertension and/or intrauterine growth retardation, and to examine the diagnostic potential for predicting adverse perinatal outcomes in complicated pregnancies compared with uterine and umbilical artery flow velocity waveforms. In this cross-sectional study, 160 normal and 43 complicated pregnancies were assessed by color and pulsed Doppler during 18-41 weeks of gestation. Flow velocity waveforms were obtained from the spiral, uterine and fetal umbilical arteries. In normal pregnancies, the resistance index of spiral artery flow velocity waveforms decreased significantly with advancing gestation (r = -0.256, p < 0.001). In abnormal pregnancies complicated by pregnancy-induced hypertension and/or intrauterine growth retardation, the incidence of adverse perinatal outcome was significantly higher in patients with abnormal spiral artery resistance indices than in patients with normal spiral artery resistance indices (p < 0.001). An abnormal spiral artery resistance index had a better diagnostic accuracy for adverse perinatal outcome (sensitivity 85.0%, specificity 91.3%, positive predictive value 89.5%, negative predictive value 87.5%, accuracy 88.4%) when compared with the resistance index of uterine and umbilical artery waveforms and presence of a diastolic notch of the uterine artery waveform. Color flow imaging facilitates the precise analysis of spiral artery flow velocity waveforms and provides more accurate information about the uteroplacental circulation in the evaluation of placental function.

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