Right hemihepatectomy in presence of congenital absence of portal vein bifurcation: a challenging but feasible procedure.

Preoperative radiologic findingsAs an example, we present a 3-phase liver CT scan with3-dimensional vascular reconstruction performed for vol-ume estimation in a patient who is a candidate to undergoRH for a single large liver metastasis from colorectal neo-plasm localized in the right liver and invading the righthepatic vein. The images demonstrate the congenital ab-sence of PV bifurcation at the hilum, with the main PVentering the liver like a right paramedian vein, then cross-ing the liver parenchyma of segment IVb transversally to-ward the left and reaching the umbilical fissure, where itturns down and, in the inferior surface of the liver, formsthe Rex’s recessus with its branches for segments II and III(Fig. 1). As reported previously, the intraparenchymalLBPVformsanarch,withanascendingportionrunningintherightparamediansectorreleasingbranchesforsegmentV and a transverse portion releasing branches for segmentVIII; the portal supplies for the right paramedian sectororiginatefromtheexternalanddorsalpartofthearch,andthe internal aspect embraces the origin of the median he-patic vein and release branches for segment IVb (Figs. 1A,1B). As shown in Figure 1C, a preoperative 3-dimensionalvascularandparenchymalreconstructionroutinelyusedinourcenterbeforeeverymajorliverresectionwashelpfultoplanthelineoftransectiontosparetheportalsupplyfortheremnant left liver.Surgical techniqueThe patient is placed in a supine position. A J-shaped in-cisionisusedtoentertheperitonealcavity.ThefirststepistodissectthemainPVatthehilumandplaceavessel-looparoundit.Theanatomyofthearterialandbiliarysystemisverified and is usually found to follow the normal branch-ing pattern, as demonstrated by Couinaud.