Subdivision of liver anterior segment into two units according to hepatic venous drainage

In anatomic liver resection, consideration of the distribution of the hepatic vein is important for maximizing remnant liver function. We have examined the anterior segment of the liver tomographically and subdivided it according to the hepatic venous distribution.

Thirty patients in whom liver tumors were diagnosed and who were examined by three-dimensional computed tomography were reviewed. Portal and hepatic venous distributions in the anterior segment were analyzed using the tomograms obtained, and the anterior segment was divided into the ventral and dorsal units.

S8d was present in only 23 cases, out of which in 14 cases, drainage veins were present. When P8d was supplied by P8, S8d together with S8a were classified into the ventral unit (8 cases). When P8d was supplied by P8c, S8d and S8b and S8c were in the dorsal unit (4 cases). S5a was in the ventral unit in 26 cases and the dorsal unit in 4 cases. S5b was in the ventral unit in 11 cases and in the dorsal unit in 19 cases. The ventral unit was drained by the middle, and the dorsal by the right, hepatic vein.

Three-dimensional computed tomography made it possible to classify the anterior segment into ventral and dorsal units according to the distribution of the hepatic vein. This new classification makes possible new operative procedures in which resection is limited to one of the units with or without one or more segments, and which result in better remnant liver function.