When the liver suffers from cirrhosis or another intra-hepatic obstruction, blood in the portal vein becomes congested and "backed-up". This can lead to a decrease in metabolic activity, resulting in a decreased clearance of drugs.
The increased pressure in the portal vein leads to dilation of the vessels (oesophageal varices), which in turn can cause rupture of the vessel wall and gross bleeding in the oesophageal lumen.
In addition to oesophageal varices, portal hypertension can lead directly to all of the following EXCEPT:
Extra info: The pathophysiological theories of hepatic encephalopathy generally center around altered ammonia metabolism, not portal hypertension.