Etiology

Portal hypertension in children can be divided into two major categories based upon the anatomic location of the increased portal resistance. Extrahepatic portal hypertension (EHPH) is most commonly the result of portal vein obstruction due to thrombosis. Risk factors for portal vein thrombosis include umbilical vein catheterization, neonatal sepsis, blunt abdominal trauma and omphalitis; idiopathic cases are also common. The thrombosis frequently recanalizes which results in cavernous transformation of the portal vein into numerous smaller channels. Other causes of EHPH include the Budd-Chiari syndrome, portal vein sclerosis and an extrahepatic artery-portal venous fistula.

Intrahepatic portal hypertension (IHPH) is typically associated with congenital liver or biliary diseases in children. Biliary atresia is by far the most common cause of IHPH in children, followed by cystic fibrosis. Other etiologies include sclerosing cholangitis, familial cholestatic syndromes, α-1-antitrypsin deficiency, hemochromatosis, Wilson's disease, viral hepatitis, autoimmune hepatitis, or idiopathic neonatal hepatitis. Manifestations of liver disease appear long before the sequelae of portal hypertension in most of these children.

Each of the causes of elevated portal pressure shares the common mechanism of increased resistance to blood flow from the splanchnic portal circulation to the right atrium (Table 4.6). In children, the location of this increased vas­cular resistance can be: (a) pre-hepatic, usually within the portal vein and its primary feeding branches; (b) intra-hepatic, most commonly related to intrinsic liver disease, but may be secondary to presinusoidal obstruction (congenital hepatic fibrosis or schistosomiasis); or, (c) post-hepatic, secondary to hepatic vein outflow obstruction.

Table 4.6

Pediatric diseases associated with portal hypertension

Pre-hepatic causes · Extrahepatic portal vein thrombosis · Cavernous transformation of the portal vein · Splenic vein thrombosis · Congenital portal vein malformation (web or diaphragm) · Extrinsic portal vein compression
Intra-hepatic causes Hepatocellular disease
  • Autoimmune hepatitis
  • Hepatitis B, C
  • Wilson's disease
  • Alpha-1-antitrypsin deficiency
  • Glycogen storage disease - type IV
  • Toxins and Drugs
  • Histiocytosis X
  • Gaucher's disease
Biliary tract disease
  • Biliary atresia
  • Cystic fibrosis
  • Intrahepatic cholestasis syndromes
  • Sclerosing cholangitis
Congenital hepatic fibrosis Schistosomiasis Sinusoidal veno-occlusive disease
Post-hepatic causes   · Budd-Chiari syndrome · Inferior vena cava obstructions (web) · Chronic congestive heart failure · Veno-occlusive disease (s/p bone marrow transplantation) · Postoperative hepatic vein stenosis · Prothrombotic disease
Hyperkinetic causes (high flow) Arteriovenous fistula (congenital or acquired)