Trifurcation of Right Portal Vein: A Rare Anatomic Variation

Abstract The portal sinus is the crossing point of three vessels: The umbilical vein and the left and right portal branches. The main portal vein gives rise to the right and left portal veins. Normally, on the right side, the right portal vein (RPV) is further divided into anterior and posterior branches that supply the posterior–inferior and posterior–superior Couinaud's segments 6 and 7, and an anterior branch that supplies the anterior–inferior and anterior–superior segments. On the left lobe, the lateral segment (Couinaud's segment 2) is supplied by the left portal vein (LPVs), and the Left Portal Vein inferior branch (LPVi) supplies the left (para)median (Couinaud's segment 3). On the right side of the umbilicoportal tract, the Left Portal Vein medial branch (LPVm) supplies the right (para)median segment (Couinaud's segment 4).