Studies on fetal lung/brain circulation by means of power Doppler technique have suggested a marked reduction in lung perfusion in high-risk pregnancies as a sign of circulation redistribution. The ratio between lung/brain perfusion might therefore give a new method to predict fetal circulation centralization.
Objective: The aim of the present study was to obtain fetal lung and cerebral artery ratio in normal and high-risk pregnancies.
Study design: Doppler samples from proximal right pulmonary artery blood velocities and middle cerebral artery (MCA) were recorded cross-sectionally in 228 normal singleton pregnancies at gestational age 22 to 40 weeks. MCA/right pulmonary artery pulsatility index (PI) ratio was calculated. Doppler samples from proximal right pulmonary artery and MCA were also recorded in 89 high-risk singleton pregnancies and the results related to perinatal outcome.
Results: In the normal controls, right pulmonary artery PI remained stable until 30 weeks of gestation with slight increase thereafter until term. The MCA to right pulmonary artery PI ratio increased between 22 and 28 weeks of gestation with the rapid fall towards term. In the high-risk pregnancies group, right pulmonary artery PI showed no significant correlation to perinatal outcome, but signs of brain-sparing in the MCA were correlated to all adverse outcome parameters.
Conclusion: Velocimetry of the middle cerebral artery is better than velocimetry of right pulmonary artery in predicting adverse outcome of pregnancy The brain/lung PI ratio does not improve the prediction of adverse outcome of pregnancy.