A comparative study of fetal umbilical velocimetry with continuous- and pulsed-wave Doppler ultrasonography in high-risk pregnancies: Relationship to outcome

Abstract

Systolic/diastolic ratios of umbilical velocimetry obtained with either continuous-wave or pulsed-wave Doppler ultrasonography have been used to assess downstream placental vascular resistance and fetal well-being. The purpose of this study is to compare the efficacy of systolic/diastolic ratios obtained by continuous-wave and pulsed-wave Doppler ultrasonography in the prediction of poor pregnancy outcome. Continuous-wave and pulsed-wave umbilical velocimetry was performed and systolic/diastolic ratios were measured in 200 high-risk pregnancies in the third trimester by use of Angioscan III and a General Electric RT 3600 scanner, respectively. A total of 165 study participants had normal systolic/diastolic ratios and 35 participants had elevated ratios (greater than 3.0) with both continuous-wave and pulsed-wave Doppler ultrasonography. Both methods identified 35 participants with abnormal ratios, and none of the women was misclassified by either method. The pulsed-wave and continuous-wave values for 35 participants with elevated ratios were 6.35 +/- 1.52 and 6.23 +/- 1.58, respectively; values for 165 participants with normal ratios were 1.95 +/- 0.40 and 1.96 +/- 0.41, respectively (not significantly different). Participants with elevated systolic/diastolic ratios within 7 days of delivery had significantly higher incidence of adverse pregnancy outcome as judged by small-for-gestational-age fetuses, presence of meconium at delivery, fetal distress in labor, cesarean sections and 5-minute Apgar scores less than 7. Fetuses with elevated ratios were delivered at an earlier gestational age (34 +/- 1.2 weeks), had lower birth weights (1422 +/- 151 gm), and spent more time in the neonatal intensive care unit (17.1 +/- 5.2 days), compared with fetuses with normal ratios (delivered at 38.5 weeks +/- 0.9 weeks, 3100 +/- 210 gm birth weights, and 2 +/- 0.2 days spent in neonatal intensive care units, respectively, p less than 0.05). We therefore conclude that continuous-wave and pulsed-wave Doppler ultrasonography produce similar results with regard to systolic/diastolic ratios in high-risk pregnancies, and either method appears to be a valuable adjunct in the surveillance of high-risk pregnancies.