Biliary atresia pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Pathophysiology
As the biliary tract cannot transport bile to the intestine, bile is retained in the liver (known as stasis) and results in cirrhosis of the liver.
There have been many theories about etiopathogenesis such as Reovirus 3 infection, congenital malformation, congenital CMV infection, autoimmune theory. This means that the etiology and pathogenesis of biliary atresia are largely unknown. However, there have been extensive studies about the pathogenesis and proper management of progressive liver fibrosis, which is arguably one of the most important aspects of biliary atresia patients. As the biliary tract cannot transport bile to the intestine, bile is retained in the liver (known as stasis) and results in cirrhosis of the liver. Proliferation of the small bile ductules occur, and peribiliary fibroblasts become activated. These "reactive" biliary epithelial cells in cholestasis, unlike normal condition, produce and secrete various cytokines such as CCL-2 or MCP-1, Tumor necrosis factor (TNF), Interleukin-6 (IL-6), TGF-beta, Endothelin (ET), and nitric oxide (NO). Among these, TGF-beta is the most important profibrogenic cytokine that can be seen in liver fibrosis in chronic cholestasis. During the chronic activation of biliary epithelium and progressive fibrosis, afflicted patients eventually show signs and symptoms of portal hypertension (esophagogastric varix bleeding, hypersplenism, hepatorenal syndrome(HRS), hepatopulmonary syndrome(HPS)). The latter two syndromes are essentially caused by systemic mediators that maintain the body within the hyperdynamic states.
Associated anomalies include, in about 20% cases,
- Cardiac lesions
- Polysplenia
- Situs inversus
- Absent vena cava
- A preduodenal portal vein