Budd-Chiari syndrome

Etiology and causes of occlusion

Budd-Chiari syndrome belongs to the group of vascular hemodynamic disorders causing hepatic venous congestion. Occlusion of the hepatic veins can result from thrombosis, congenital developmental anomalies (e.g., a membrane in the lumen of the inferior vena cava), as well as external compression by dense fibrous adhesions or a growing tumor.

In descending order of frequency, the main factors triggering hepatic vein thrombosis are distributed as follows:

1. Polycythemia vera.
2. Conditions associated with pregnancy and the postpartum period.
3. Use of oral contraceptives.
4. Paroxysmal nocturnal hemoglobinuria.
5. Malignant abdominal tumors (especially hepatocellular carcinoma — HCC).

It is important to note that in approximately 30% of patients, the exact cause of the disease cannot be determined.

Clinical presentation and morphological changes of the liver

Classic clinical manifestations of the syndrome include hepatomegaly (enlargement of the liver), rapid weight gain due to fluid accumulation, ascites, and severe abdominal pain.

The macroscopic appearance of liver tissue directly depends on the rate of development of the vascular event:

• In acute occlusion: the liver becomes markedly edematous and takes on a rich purple-red color. The Glisson's capsule of the organ is severely tense due to acute blood engorgement.
• In the chronic course: signs of local venous congestion come to the forefront. Prolonged venous blood stasis leads to a specific pattern — the development of "nutmeg liver". Subsequently, chronic hypoxia triggers connective tissue proliferation: nutmeg fibrosis progresses and predictably turns into liver cirrhosis.

Development of portal hypertension

As cirrhosis develops in the liver, a diffuse sclerotic process unfolds. Dense connective tissue compresses the microvasculature, creating a serious mechanical obstacle to blood flow. As a result, blood flow from the portal vein to the hepatic vein is impeded, leading to venous congestion and a persistent increase in pressure within the portal venous system — portal hypertension syndrome.

The body attempts to compensate for this condition by shunting blood bypassing the liver through portosystemic anastomoses. This leads to severe consequences:

• Esophageal varices.
• Gastric cardia varices.
• Hemorrhoidal plexus varices of the rectum.
• Dilatation of subcutaneous veins of the anterior abdominal wall (clinical sign of "caput medusae").
• Progressive ascites.

Splenic changes (congestive splenomegaly)

Increased pressure in the portal venous system inevitably affects the spleen, causing congestive splenomegaly. Macroscopic and microscopic examination reveals the following changes:

• Significant increase in organ weight (up to 700 g or more, with a normal weight of about 150 g).
• Marked dilation of sinusoids with blood.
• Development of hemosiderosis (pigment deposition from destroyed erythrocytes) and splenic pulp sclerosis.

Differential diagnosis of hemodynamic disorders

Budd-Chiari syndrome is only one of the causes of venous congestion. It must be differentiated from cardiac factors that also lead to liver congestion and enlargement. Cardiac causes include:

• Congestive heart failure (right-sided).
• Constrictive pericarditis (compression of the heart by a thickened pericardium, preventing adequate diastolic filling).
• Valvular heart disease, primarily tricuspid regurgitation, which leads to backflow of blood into the inferior vena cava and liver.

Class and exam questions

What else to study on this topic

• Morphogenesis of liver cirrhosis and stages of nutmeg fibrosis
• Portosystemic anastomoses: anatomy and clinical significance
• Hepatocellular carcinoma (HCC) as a cause of vascular complications
• Pathogenesis of ascites in portal hypertension
• Morphological changes in congestive heart failure

Other topics in the "Additional Topics" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.