Abstract：Objective: To study the Doppler flow spectrum of fetal hepatic vein and inferior vena cava and determine the gestational age-related reference range of their preload index. Methods: Doppler measurements were obtained for the 4 veins of 118 normal fetuses at the 26~40 week of gestation. A and S values were measured from the recorded flow velocity waveform of each vein and the A/S ratio was calculated and analyzed as the preload index. Results: There was a three-phase blood flow spectrum which could be observed in the hepatic vein and the inferior vena cava. The A/S ratios decreased gradually with the increase of the gestational age, which were less than 0.5. There was no significant difference between the four regression equations. Conclusions: The flow indexes of fetal hepatic vein and inferior vena cava are statistically similar, which may be utilized as an index for the estimation of fetal cardiac function.
2015, Vol. 26 
