Power Doppler signals of fetal brain and lung blood flow in normal and high-risk pregnancies

Objective The aim of this study was to evaluate blood flow in the fetal bra in and lung by means of computer analysis of power Doppler ultrasound image s in normal and high-risk pregnancies. Study design Fetal brain and lung power Doppler signals were recorded in a combined longitudinal and cross-sectional study of 35 normal and 43 high-ri sk singleton pregnancies of 27-42 weeks' gestation. A fixed preinstalled ul trasound system for each organ was used during the examination. Power Doppl er images were recorded on videotape and fed into a computer for analysis. Mean flow signal intensity and 95% confidence intervals were constructed fo r normal pregnancies and then compared with findings in high-risk pregnanci es. Brain/lung power Doppler intensity ratios were calculated. Results As term approached, the fetal cerebral power Doppler signal intensi ty increased and the lung signal intensity decreased. The brain/lung ratio increased towards the end of gestation. Twenty of the high-risk pregnancies had an increased power Doppler brain/lung ratio, which was associated with preterm delivery and newborn acidosis. Conclusion Increased fetal brain and decreased lung blood flow at the end o f normal pregnancy may indicate a redistribution of the feta I circulation as a physiological response to a relative decrease in placental perfusion. In high-risk pregnancies, an increase in the power Doppler brain/lung signa l intensity ratio may be an indicator of fetal compromise.