Daily variability of umbilical and lateral uterine wall artery blood velocity waveform measurements

Abstract

The daily variability of umbilical artery and lateral uterine wall artery velocity-time waveforms recorded by continuous wave Doppler ultrasound was determined by making three observations in each of 97 women on different days within a 7-day period. There were no significant changes in the maximal:minimal Doppler shift frequency (A/B ratio) or the pulsatility index in either artery over the period of study. Common pregnancy complications did not influence the variability of the recordings. The variability of uterine artery recordings was not affected by gestational age between 17 and 41 weeks but the degree of variability of the umbilical artery recordings was greater before 30 weeks. We conclude that after 30 weeks gestation this technique has an acceptable range of daily variability for clinical and research applications.