Question

Extrahepatic portal hypertension: Pathophysiology.

Hint:

EHPH is typically caused by a blockage of the portal vein or its branches, and the key feature is the development of collateral circulation to bypass the blockage.

Answer 1

Step 1: Pathophysiology of Extrahepatic Portal Hypertension.
Extrahepatic portal hypertension (EHPH) is a condition where there is increased pressure within the portal venous system due to obstruction or narrowing of the extrahepatic portal vein. The pathophysiology includes:
(1) Obstruction of the Portal Vein: The most common cause is thrombosis or fibrosis of the extrahepatic portal vein. This leads to impaired blood flow and increased pressure in the portal system.
(2) Development of Collateral Circulation: As a result of the obstructed portal flow, collateral veins (e.g., esophageal, gastric, or rectal veins) dilate to bypass the obstruction, leading to varices and other complications.
(3) Increased Portal Pressure: The backup of blood increases pressure in the spleen and gastrointestinal tract, leading to splenomegaly and variceal bleeding.
(4) Liver Function: In EHPH, the liver is usually not involved in the obstructive process, unlike cirrhosis. However, portal pressure rises as a result of the obstruction or thrombosis of the extrahepatic portal vein.