[Segment I of the liver or spigelian lobe. Anatomic study and surgical value]

Spigel's lobe, or segment I of the liver, currently represents the "smallest amount of hepatic parenchyma capable of regeneration". It is an autonomous lobe by virtue of its site and vasculo-biliary distribution, a true "accessory" liver connected to the "main" liver. Lesions of Spigel's lobe are rare, which is explained by the anatomy of the portal bifurcation. Hence the value of making every effort to preserve this segment during hepatectomy because of the possibilities of additional hepatic vein drainage. Segment I surgery is difficult and falls within the context of extended hepatectomies. Can Spigel's lobe be considered to be a "safety liver"? The possibility of subtotal hepatectomy, retaining only segment I, is being studied in the animal. It may be possible in man in the case of extensive hepatic lesions where only segment I is unaffected, as soon as effective artificial liver support is developed.