Division of the left hemiliver in man--segments, sectors, or sections.

A major obstacle to coherent terminology for liver anatomy and resections has been that American and French anatomists have divided the left side of the liver through different planes. Couinaud divided the left hemiliver into "sectors" by a plane through the left hepatic vein. Healey and Schroy divided it into "segments" through the umbilical fissure. One anatomic justification for Couinaud's system of sectors is that the transverse portion of the left portal vein was said to terminate by dividing into the umbilical portion of the left portal vein and the vein to segment II. However, corrosion cast studies fail to consider the position of the ligamentum venosum, the structure defining the end of the transverse portion of the left portal vein. Therefore, it is uncertain whether the branch to segment II is a terminal branch of the transverse portion of the left portal vein or a branch of the first part of the umbilical portion. Ten cadaver livers were dissected to determine the position of the branch to segment II in relation to the ligamentum venosum. In all, the branch to segment II came off downstream to the ligamentum venosum, showing that it is a branch of the umbilical portion of the left portal vein. This study does not support the "sectoral" system of Couinaud on the left side of the liver. Division of the left side of the liver through the umbilical fissure as proposed by Healey is anatomically logical and fits well with common surgical resections.