Budd-Chiari Syndrome Definition
Budd-Chiari syndrome (BCS) is a rare disorder defined as the obstruction of hepatic venous outflow, ranging from the small hepatic venules up to the entrance of the inferior vena cava (IVC) into the right atrium 1.
Key Defining Features
The syndrome specifically excludes hepatic outflow obstruction caused by:
- Cardiac disease
- Pericardial disease
- Sinusoidal obstruction syndrome (SOS)
Classification
BCS is classified into two types 1:
- Primary BCS: Caused by thrombosis without compression from space-occupying lesions, malignancy invasion, or parasites
- Secondary BCS: All other causes (e.g., extraluminal compression from abscesses, tumors, or cysts)
Geographic Variations in Presentation
The anatomic pattern differs by region 1:
- Western countries: Pure hepatic vein thrombosis is most common
- Asia: Pure IVC obstruction or combined IVC/hepatic vein block predominates
Pathophysiology
The obstruction leads to a cascade of hepatic injury 1:
- Sinusoidal congestion
- Ischemia
- Hepatocellular necrosis
- Centrilobular fibrosis
- Nodular regenerative hyperplasia and/or cirrhosis
Clinical Presentation Spectrum
The clinical presentation is highly heterogeneous, ranging from completely asymptomatic patients (3% of cases) to fulminant hepatic failure 2, 3. Common findings at diagnosis include 1:
- Ascites: 83% of patients
- Hepatomegaly: 67% of patients
- Abdominal pain
Asymptomatic presentations typically occur when large hepatic venous collaterals are present.
Common Etiologies
Myeloproliferative neoplasms are the most prevalent underlying cause, present in more than 40% of cases 3. Other important risk factors include 2:
- Prothrombotic conditions
- Oral contraceptive use
- Lower socioeconomic status and malnutrition