What anatomy of the liver must be understood for the treatment of hepatocellular carcinoma (HCC)?

Updated: Jan 31, 2021
  • Author: Luca Cicalese, MD, FACS; Chief Editor: John Geibel, MD, MSc, DSc, AGAF  more...
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Answer

A complete understanding of the surgical and interventional approach to the liver requires a comprehensive understanding of its anatomy and vascular supply. [5, 6] The liver is the largest internal organ, representing 2-3% of the total body weight in an adult. It occupies the right upper quadrant of the abdomen, surrounding the inferior vena cava, and attaches to the diaphragm and parietal peritoneum by various attachments that are commonly referred to as ligaments.

The vascular supply of the liver includes two sources of inflow that travel in the hepatoduodenal ligament, as follows:

  • Hepatic artery
  • Portal vein

The hepatic artery is generally derived from the celiac axis, which originates on the ventral aorta at the level of the diaphragm. Common variations include a replaced right hepatic artery, which originates from the superior mesenteric artery, a replaced left hepatic artery, which is derived from the left gastric artery, or a completely replaced common hepatic artery, which can originate from the superior mesenteric artery or the aorta. The hepatic artery supplies 30% of the blood flow to the normal liver parenchyma but greater than 90% to hepatic tumors, including both HCC and metastatic lesions.

The other major inflow vessel is the portal vein which carries 70-85% of the blood into the liver. The portal vein is confluence of the splenic vein and the superior mesenteric vein, which drain the intestines, pancreas, stomach, and spleen.

The primary venous drainage of the liver is through three large hepatic veins that enter the inferior vena cava adjacent to the diaphragm. The right hepatic vein is generally oval in shape, with its long axis in the line of the vena cava. The middle and left hepatic veins enter the inferior vena cava through a single orifice in about 60% of individuals. In addition, there are 10-50 small hepatic veins that drain directly into the vena cava.

The biliary anatomy of the liver generally follows hepatic arterial divisions. The common bile duct gives off the cystic duct and becomes the hepatic duct. The hepatic duct then divides into two or three additional ducts draining the liver. There is significant variation in the biliary anatomy, and thus, careful preoperative imaging is vital before any major hepatic resection. [5]

The vascular anatomy of the liver defines its functional segments. Bismuth synthesized existing knowledge and new insight into the anatomy of the liver. [7] Bismuth defined the right and left hemilivers, which are defined by a line connecting the gallbladder fossa and the inferior vena cava, roughly paralleling the middle hepatic vein that is slightly to the left. [7]

The right hemiliver (lobe) is divided into four segments (ie, 5, 6, 7, 8), each of which is supplied by a branch of the portal vein. The right hemiliver drains via the right hepatic vein. The left hemiliver (lobe) is composed of three segments (ie, 2, 3, 4). Segment 4 is the most medial and is adjacent to the middle hepatic vein. Segments 2 and 3 make up the left lateral section, are to the left of the falciform ligament, and drain via the left hepatic vein. Finally, segment 1 (caudate lobe) is located behind the porta hepatis and adjacent to the vena cava.

In general, resection of the liver is divided into the following two main categories [8] :

  • Nonanatomic (wedge) resections are generally limited resections of a small portion of liver, without respect to the vascular supply
  • Anatomic resections involve removing one or more of the eight segments of the liver

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