11 The liver and spleen

Questions

What is the most common type of liver malignancy in the UK?

What are the complications of splenectomy?

The Liver

The liver has a dual blood supply, from the hepatic artery (arterial blood) and the hepatic portal vein (splanchnic blood). The hepatic portal vein is formed from the splenic vein and the superior mesenteric vein. The common bile duct, hepatic artery and portal vein form the portal triad. Three main hepatic veins drain from the liver into the inferior vena cava.

Portal hypertension

Portal hypertension (Fig. 3.11.1) occurs when the outflow to the hepatic portal vein is blocked, causing backflow. The portal system has five sites of anastomoses with the systemic circulation (portal systemic anastomoses; Table 3.11.1). When portal hypertension occurs, portal blood flow through these sites increases and causes formation of varices. The most important site is the lower oesophagus, as these oesophageal varices may cause massive upper gastrointestinal haemorrhage and possibly death (Ch. 8). Portal hypertension can also cause ascites (below).

Fig. 3.11.1 Causes of portal hypertension.

Table 3.11.1 Portosystemic Anastomoses

Area	Portal veins	Systemic veins
A Lower oesophagus	Left gastric	Azygos (via oesophageal veins)
B Rectum	Superior rectal into inferior mesenteric	Middle/inferior rectal into pudendal/internal iliac
C Bare area of liver	Hepatic	Inferior phrenic
D Periumbilical	Paraumbilical vein	Anterior abdominal wall
E Retroperitoneum	Colic and splenic	Lumbar

Management

The transjugular intrahepatic portosystemic shunt (TIPS; Fig. 3.11.2) may be used for long-term management. It is an interventional radiological procedure. A metallic stent creates a communication between the hepatic vein (low pressure) and the portal venous system (high pressure), allowing blood to flow into the inferior vena cava without passing through the liver.