What is a common cause of pre-hepatic portal hypertension?

Pre-hepatic portal hypertension occurs due to causes that affect the blood flow before it reaches the liver. One of the most recognized reasons for this condition is portal vein atresia, which is the complete or partial obstruction of the portal vein either at birth or developing later in life. This obstruction prevents normal blood flow from the intestines and spleen to the liver, consequently raising the pressure in the portal venous system.

In contrast, hepatic fibrosis, splenic neoplasia, and cirrhosis all lead to post-hepatic or intrahepatic conditions rather than pre-hepatic. Hepatic fibrosis and cirrhosis cause increased resistance to blood flow through the liver itself due to structural changes in the liver tissue. Splenic neoplasia can contribute to an increase in splenic size and alterations in splenic circulation, but it does not directly obstruct the portal vein like atresia does. Understanding these distinctions is vital for diagnosing and managing liver-related vascular conditions effectively.