Proposal for a reclassification of liver based anatomy on portal ramifications

Portal branching patterns that differ from those previously described are occasionally encountered during liver surgery. A total of 60 patients with normal intrahepatic venous anatomy underwent helical computed tomography during arterial portography (CTAP). Next, 3 dimensional portograms were reconstructed to verify the locations of the portal veins. Portal branching patterns in the right hemiliver were assessed. In all 60 patients examined, the right anterior portal vein bifurcated into the ventral and dorsal branches. In 42 (70 %) of 60 patients, some branches arose from the right posterior portal trunk. Between 1 and 3 branches (mean 2.3 branches per patient) coursed cranially, between 2 and 5 branches (mean 3.2 branches per patient) coursed caudally, and between 1 and 2 branches (mean 1.3 branches per patient) coursed laterally. We propose that the right liver should be divided into 3 segments, which are designated as the right anterior, middle, and posterior segments.