INTERRELATIONSHIP AND CLINICAL-SIGNIFICANCE OF INCREASED RESISTANCE IN THE UTERINE ARTERIES IN PATIENTS WITH HYPERTENSION OR PREECLAMPSIA OR BOTH

OBJECTIVES: This study was designed to evaluate the clinical significance of the Doppler flow velocity waveform analysis of the two uterine arteries on an individual basis and in combination expressed as the mean uterine artery. STUDY DESIGN: We evaluated uterine artery resistance by means of continuous wave Doppler ultrasonography in 123 pregnant women with chronic hypertension, preeclampsia, or both. The placental location was determined by real-time ultrasonography. Clinical outcomes were compared according to uterine artery abnormalities. The Doppler flow studies were not used in patient management. RESULTS: In patients with unilateral placentas (n = 67) the placental uterine artery was found to be a better predictor of poor pregnancy outcome than the nonplacental artery and the mean of the two arteries. There was a strong degree of correlation between abnormal nonplacental uterine artery and abnormal mean of uterine artery (r = 0.75, p < 0.001), and there was a moderate degree of correlation between abnormal placental uterine artery and abnormal mean uterine artery (r = 0.46, p < 0.001). Uterine artery discordance (left - right uterine artery systolic/diastolic ratio) was mostly the result of an abnormal nonplacental uterine artery (r = 0.74, p < 0.0001) and not the result of an abnormal mean uterine artery (r = 0.44, p < 0.003); the degree of discordance did not relate to pregnancy outcome. Unilateral palcental location was associated with longer stays in neonatal intensive care units and more perinatal deaths. CONCLUSION: Because of the differences between the two uterine arteries, we conclude that for proper interpretation of uterine artery flow velocity waveforms, the placental location should be known and each vessel analyzed individually.