[Segmentation of the liver and anatomical variants of the portal system]

The authors, who studied 605 human livers according to various techniques, present their own anatomo-surgical conception of human liver segmentation, based on the distribution of the whole intrahepatic Glisson's system, and by dividing the liver into two hemi-livers, right and left (the term "lobe" being reserved, according to Tôn-Thât-Tùng, for the classical anatomical lobes): the right hemi-liver is subdivided into two segments: anterior and posterior; the left hemi-liver is subdivided into three segments: medial (IV), lateral-anterior (III) and lateral-posterior (II); the dorsal segment (I) or the classical Spigel's lobe tends to overlap both half livers (more on the left than on the right). The authors then describe, indicating the percentages, the typical patterns and anatomical variants of intersegmental fissures and the portal system. During the discussion, the authors say that, according to their experience, the right hemi-liver segments can be divided into some smaller units: the posterior segment into two subsegments (VI and VII) and the anterior ones into three subsegments (V, VIIIi and VIIIe); and they justify the segmental division of the left hemi-liver. The authors conclude that statistical and analytical study can define a typical anatomical pattern but that, owing to many anatomical variants, it is easier to perform the transparenchymal approach to the vasculo-biliary structures, enveloped in the same Glisson's capsule, rather than to make long and dangerous dissections at the porta hepatis.