Ultrasound of the fetal veins part 1: the intrahepatic venous system.

Advances in high-resolution ultrasound combined with color Doppler and three-dimensional (3 D) rendering have contributed to an increasing understanding of the fetal venous circulation in recent years. Still the sonographic evaluation of the venous system in the fetus remains difficult. This article reviews the normal and abnormal intrahepatic venous system. Normal anatomy and abnormal findings of the umbilical vein (UV), the ductus venosus (DV), portal veins, hepatic veins and the inferior vena cava are demonstrated by grayscale, color Doppler and 3D ultrasound and explained by numerous schemes. Typical variants and abnormalities such as agenesis of the DV and portal venous system, persistence of the right UV, UV varix are explained and the clinical value of normal and abnormal Doppler findings in the DV is discussed. Many of these abnormal findings can be detected by a targeted examination of the intrahepatic vasculature with means of color Doppler.