Intrahepatic Porto-Ductus Venosus Shunt: A Rare Prenatal Variant Mimicking Ductus Venosus Duplication

Abstract The ductus venosus (DV), a branchless hourglass-shaped vessel, is an extracardiac type shunt that redirects maternal oxygenated blood from the umbilical vein to the fetal heart, bypassing the liver. Anatomical variations in the fetal DV can include agenesis, abnormal drainage, size and course variations, and atypical flow patterns. In about 1 in 500 to 2,500 pregnancies, the DV is either missing or drains at an unusual site. Duplication or double DV, a very rare anatomical variation with two DV instead of one, remains challenging to understand due to limited prenatal and postnatal research. We describe a rare fetal vascular variant in which an accessory vessel from the portal sinus joins the DV before its drainage into the infracardiac inferior vena cava (intrahepatic porto-DV shunt). On spectral Doppler imaging, both the individual vessels and the common segment showed triphasic waveforms. To our knowledge, this is the first reported case in the current literature. This variant may have implications for fetal hemodynamics and portal system development, underscoring the need for detailed prenatal imaging and further embryological research.