A comparative study of continuous- and pulsed-wave Doppler velocimetry in fetal and uteroplacental circulation.

Abstract

Continuous-wave and pulsed-wave Doppler ultrasonography are the two common methods used to study the fetal and uteroplacental circulation. We used both methods in the same patient population in three different gestations and in various fetal and uteroplacental vessels to compare the results from both machines. Thirty-one normal patients were studied at 20, 28, and 36 weeks gestation. The results showed significant correlation with no statistically significant differences between the two types of machines for the peak systolic/end-diastolic ratios and resistance index for the umbilical artery and uterine arteries. Significant differences, however, were demonstrated when the arcuate artery was studied, or when the pulsatility index was used for comparison. We therefore conclude that when different machines are used for study, comparison of the results is only valid for selected vessels and indices. Results for arcuate arteries and pulsatility index should be compared with caution.

Flow Velocity Waveforms of the Uterine Artery in Pregnancy: Transvaginal versus Transabdominal Approach

“…Both the CWD and PWD techniques can be used to study uterine hemodynamics in pregnancy. Similar uterine artery indices were obtained by PWD even when Color Doppler imaging was used [10], when compared to results from a CWD study [4], Chan et al [11] did not register any differences between indices obtained by PWD or CWD from the uterine artery, but significant differences were demonstrated when the arcuate arteries were studied. In other studies [12,13], no differences in the FVWs were noted between signals obtained from the arcuate or uterine arteries in the two techniques.…”

“…It is programmed to use waveforms of 14-second duration for analysis. For example, a maternal heart rate of 80 beats/min, about 18 waveforms are analyzed, while only 2-5 waveforms are used for analysis in PWD [2,3,11] or CWD machines [4,11], Furthermore, in our system, pro cessing of waveforms is fully computerized, while in the majority of other systems, manual measurements by cal ipers are performed. Our system ensures that accurate measurements were uniformly provided throughout the study.…”