Hepatic venous outflow obstruction
- Lesion
If blood cannot leave the liver, it swells, becomes painful and congested, and the cells near the central vein die.
What it is
Obstruction to outflow at the level of the hepatic veins (Budd-Chiari syndrome), the small terminal venules and sinusoids (sinusoidal obstruction syndrome) or the heart (right heart failure) causes centrilobular congestion, hepatomegaly and ascites. Low flow from shock adds centrilobular necrosis. Chronic congestion leaves the classic nutmeg liver and, in long-standing heart failure, cardiac sclerosis.
Structure
- Acute: enlarged, tense, red-purple liver; centrilobular congestion and hemorrhage.
- Chronic: nutmeg pattern on cut surface; zone 3 fibrosis and sinusoidal dilation.
Step by step
- Venous outflow is blocked or right atrial pressure rises.
- Sinusoids around central veins dilate and fill with red cells.
- Pressure and low oxygen injure zone 3 hepatocytes; they atrophy or die.
- Plasma leaks into the space of Disse and peritoneum: hepatomegaly and ascites.
- Persistent block: perivenular fibrosis, nodular regeneration, sometimes cirrhosis.
Disorders of hepatic venous outflow
| Disorder | Level of block | Causes | Liver |
|---|---|---|---|
| Budd-Chiari syndrome | Large hepatic veins or suprahepatic cava | Myeloproliferative neoplasms, PNH, pregnancy, contraceptives, tumours | Swollen red-purple liver, zone 3 congestion and necrosis |
| Sinusoidal obstruction syndrome | Sinusoids and terminal hepatic venules | Myeloablative chemotherapy, pyrrolizidine alkaloids | Zone 3 congestion, obliterated venules, necrosis |
| Passive congestion | Heart | Right heart failure, constrictive pericarditis | Nutmeg liver; cardiac sclerosis if chronic |
| Ischemic hepatitis | Low inflow plus congestion | Shock, left heart failure | Centrilobular coagulative necrosis |
Test yourself
Think of the answer, then tap the question to see it.
Which hematologic disorders most often cause Budd-Chiari syndrome?
Myeloproliferative neoplasms such as polycythemia vera (often JAK2-mutated) and paroxysmal nocturnal hemoglobinuria.
What is sinusoidal obstruction syndrome?
Toxic injury to sinusoidal endothelium that obliterates terminal venules, seen after myeloablative chemotherapy or pyrrolizidine alkaloid ingestion.
What gives the nutmeg pattern of chronic passive congestion?
Dark red congested centrilobular regions alternating with paler, sometimes fatty, periportal parenchyma.
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Hepatic vein obstruction (Budd-Chiari): MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); Hepatic ischemia: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026).
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Representative model, for educational purposes only.