Uterine artery color Doppler assisted velocimetry and perinatal outcome.

BACKGROUND

Previously, we have found uterine artery blood velocimetry performed with Doppler ultrasound without vessel visualization to be a poor predictor of perinatal outcome. The aim of this study was to ascertain whether the combination of color Doppler imaging with the method would improve its predictive value.

METHODS

In a cross-sectional study of 110 uncomplicated pregnancies, uterine artery blood velocity was recorded bilaterally from 18 to 42 weeks of gestation to obtain reference values for pulsatility index (PI). Using color Doppler imaging, the main uterine artery was located as it crosses the iliac vessels and blood velocity was then recorded with pulsed Doppler ultrasound. The uterine and umbilical blood velocity waveforms were also obtained in 421 complicated pregnancies, and the results related to placental site and perinatal outcome.

RESULTS

In uncomplicated pregnancies, the uterine artery PI was unrelated to gestational age using 1.20 as the upper cut-off limit for the mean PI of both vessels (mean+2 s.d.). Corresponding values for unilateral placental localization were 1.00 at the placental side and 1.40 at the non-placental side. Blood velocities obtained using the color Doppler combination were similar to previously presented results. In the complicated pregnancies, significant correlation was found between abnormal perinatal outcome and abnormality of the uterine artery blood velocity waveform, either increased PI (n = 44) or a notch in early diastole (n = 92). The predictive value of an early diastolic notch was superior to an increased PI in predicting abnormal outcome. The mean PI for both uterine arteries was a better predictor of outcome than blood velocity on the placental side. The blood velocity waveforms on the non-placental side were the poorest predictors of outcome.

CONCLUSION

The addition of color Doppler imaging to pulsed wave Doppler ultrasound recording of uterine artery blood velocity improves the predictive value of blood velocity waveforms with regard to the perinatal outcome.