Definition Portal hypertension is defined as a pressure >12 mmHg This increased pressure results from a functional obstruction to blood flow from any point in the portal system s origin(in the splanchnic bed )through the hepatic veins(exit into the systemic circulation)or from an increase in blood flow in the systemDefinition • Portal hypertension is defined as a pressure > 12 mmHg. • This increased pressure results from a functional obstruction to blood flow from any point in the portal system's origin (in the splanchnic bed) through the hepatic veins (exit into the systemic circulation) or from an increase in blood flow in the system