ABSTRACT
A detailed knowledge of the intrahepatic ramification of the portal vein is fundamental for the examination and treatment of liver diseases. We studied the ramification of the portal vein 40 human left hemilivers. The hemiliver consisted of lateral superior (S2), lateral inferior (S3), and medial (S4) subsegments, of which the latter two were subdivided into superior and inferior regions. Four hundred and ninety-three branches were detected, 85 of them to S2, 132 to S3 and 276 to S4. The lateral superior portal branch (P2) was constant and ranged in caliber from 1.0 mm to 6.4 mm (meanñSD:3.6ñ1.2mm). In 3/40 cases (7.5per cent) and intermediate P2 branch was directed to the lower S2 region. The lateral inferior portal branches (P3) ranged in caliber from 1.0 mm to 7.5 mm (meanñSD:3.2ñ0.9mm). The medial P4 portal branches were more numerous but of smaller caliber, which ranged from 0.8 mm to 6.6 mm (meanñSD:2.5ñ0. 4mm). In 17/40 cases (42.5per cent), one or two branches, in addition to vascularizing their own subsegment, reached a region of the adjacent subsegment.