Fetal and placental power Doppler imaging in normal and high-risk pregnancy.

OBJECTIVE: Computer analysis of organ power Doppler (PD) imaging has recently become available. The aim of the study was to evaluate gestational trends in placenta-, fetal lung-, liver- and kidney-blood flow in normal pregnancies and relate it to signals in high-risk pregnancies. METHODS: PD signals were recorded in normal singleton pregnancies between 26 and 42 weeks of gestation. Signals were also recorded in 63 high-risk pregnancies. Fixed preinstalled PD system installations for each organ were used during examinations. Images from PD scan were recorded on video tape and off-line analysed by computer. Mean flow signal intensity was calculated for each organ. Umbilical and uterine artery Doppler velocimetry were also recorded in high-risk pregnancies. RESULTS: PD signals from the four organs indicated increasing organ blood flow until approximately 34 weeks of gestation, from where the organ signals seemed to decrease. High-risk pregnancies seemed to have lower PD signal intensity, which was more pronounced in cases with signs of placental vascular resistance. CONCLUSION: The results suggest that a decrease in fetal organ blood flow might indicate a centralisation of fetal circulation in normal pregnancy at term, as a physiological response to a decrease in placental perfusion. In the high-risk pregnancies the placental and fetal organ blood flow seem to be even further reduced, suggesting a more intense centralisation of circulation.