Portal hypertension

Portal Hypertension

Portal vein is formed by union of;
- Superior mesenteric vein
- Splenic vein

Portal hypertension classified according to the site of obstruction;
Prehepatic; blockage of the portal vein before the liver
Intrahepatic; due to distortion of the liver architecture.
Post-hepatic; venous blockage outside the liver.

Portal pressure rises above 10-12 mmHg -> compliant venous system dilates + collaterals occur within the systemic venous system.
Main sites of collaterals: gastro-oesophageal junction, rectus, left renal vein, diaphragm, retroperitoneum and anterior abdominal wall via the umbilical vein. Collaterals at the gastro-oesophaegeal jnction (varices) are superficial and tend to rupture. Other sites seldom give symptoms. Rectal varices are frequently found (30%), if carefully looked it can be differentiated from haemorrhoids.

Cause

Most common cause = cirrhosis.

Prehepatic causes: portal vein thrombosis, portal vein occlusion secondary to congenital portal venous abnormalities or neonatal sepsis of the umbilical vein, prothrombic conditions (e.g. factor V leiden)

Intrahepatic causes:
- Non-cirrhotic portal hypertension; histoligically the liver shows mild portal tract fibrosis.
- Schistosomiasis, it's confined to endemic areas, often there maybe concomitant liver disease such as HCV infection.
- Other causes; congenital hepatic fibrosis, nodular regenerative hyperplasia, partial nodular transformation.

Post-hepatic causes: prolonged severe heart failure with tricuspid incompetence, constrictive pericarditis, Budd-Chiari syndrome.

Clinical features

Often asymptomatic, only clinical evidence of portal hypertension is splenomegaly. Clinical features of chronic liver disease are usually present.