Fetal Hepatic Circulation: From Vascular Physiology to Doppler Assessment

During fetal life, the hepatic artery (HA) is responsible for a small contribution to the total hepatic blood inflow; however, it plays a key role in maintaining liver perfusion and reflects fetal hemodynamic adaptation. With advances in ultrasonography, HA Doppler assessment has emerged as a potential tool for evaluating fetal well-being. This review aims to synthesize current knowledge on the embryology, anatomy, physiology, and Doppler assessment of the fetal hepatic artery, highlighting its diagnostic and clinical significance. A prenatal hepatic arterial buffer response (HABR), analogous to that in postnatal life, allows for compensatory vasodilatation when umbilical or portal venous inflow decreases. Doppler studies demonstrate that a reduced pulsatility index (PI) and resistance index (RI) and an increased peak systolic velocity (PSV) correspond to enhanced arterial flow and decreased vascular resistance. These patterns have been observed in fetal growth restriction (FGR) and certain chromosomal abnormalities. Fetal hepatic artery Doppler assessment contributes to the understanding of fetal adaptation to hypoxia and has a promising role in fetal well-being evaluation. As of now, there are no established reference curves, and it has not yet been incorporated into routine obstetric screening; future research should focus on standardizing measurement techniques and validating its prognostic value.