Portal hypertension syndrome

Etiology and classification of blocks

Depending on the level at which the obstacle (block) to blood flow has occurred, three variants of the pathology are distinguished:

1. Intrahepatic (sinusoidal) block. This is the most frequent cause of obstructed blood flow. It is based on the proliferation of connective tissue in the interlobular spaces of the liver, leading to mechanical compression of small branches of the portal vein. The main triggers are viral and alcoholic liver cirrhosis, as well as Wilson's disease. Other causes include acute alcoholic and chronic viral hepatitis, primary forms of biliary cirrhosis, and primary sclerosing cholangitis.
2. Prehepatic (presinusoidal) block. It is localized directly in the portal vein bed prior to its entry into the liver. The vessel lumen can be occluded due to thrombosis or inflammation of the venous wall. The vein is frequently compressed from the outside by space-occupying lesions, such as tumors or enlarged lymph nodes. Rarer factors include sarcoidosis and parasitic infestations (schistosomiasis).
3. Posthepatic (postsinusoidal) block. The obstruction is located at the level of the hepatic veins or the right chambers of the heart. A typical example is Budd-Chiari syndrome, in which the hepatic veins are occluded. The block can also form with a sharp increase in central venous pressure (CVP), which is characteristic of constrictive pericarditis.

Clinical presentation: the classic triad

The full clinical picture of the syndrome is based on three classic signs:

• Collateral circulation. Since the direct path through the liver is blocked, blood is forced to bypass the obstruction. It is shunted into the superior and inferior vena cava systems, bypassing the liver. The volume of blood flow through portosystemic anastomoses increases sharply; they become overloaded and dilate. Esophageal varices are detected instrumentally. Proctoscopy reveals dilation of the superior rectal veins. Visual examination of the abdomen often reveals a characteristic picture — caput Medusae, which represents tortuous venous cords on the anterior abdominal wall. The most formidable complication is the rupture of esophageal varices. This is accompanied by life-threatening hemorrhage and the appearance of melena, a specific tarry stool.
• Splenomegaly. The spleen significantly increases in size because outflow through the splenic vein (one of the main tributaries of the portal vein) is severely impaired. Enlargement of the organ is often accompanied by hypersplenism, a syndrome of increased splenic function. Laboratory tests reflect this as pancytopenia: the patient simultaneously experiences a drop in red blood cells (anemia), white blood cells (leukopenia), and platelets (thrombocytopenia).
• Ascites. Accumulation of fluid in the abdominal cavity generally develops slowly and only after venous collaterals have formed. The only exception is acute portal vein thrombosis, in which the abdomen enlarges rapidly.

Features of the ascitic syndrome

The appearance of ascites is often preceded by prodromal phenomena, primarily persistent flatulence. Bloating occurs because venous congestion in the intestinal wall seriously disrupts digestion. As ascites progresses, the abdomen enlarges significantly, pale striae (stretch marks) appear on the skin, and umbilical and femoral hernias form.

The fluid accumulating in the cavity is initially a transudate. The mechanism of its formation is the hydrostatic transudation of the liquid part of the blood through the walls of dilated capillaries. The composition of the fluid changes in the event of complications: if an infection joins (spontaneous bacterial peritonitis), it transforms into an exudate. When lymphatic outflow is blocked, the ascites acquires a chylous character.

Massive ascites causes secondary problems:

• Fluid can migrate through the diaphragmatic lymphatics into the pleural cavity, causing hydrothorax (more frequently on the right).
• Compression of the inferior vena cava leads to edema of the lower extremities, varicocele, and the formation of collaterals on the flanks.
• Due to impaired water absorption in the intestines, the patient experiences decreased urine output (oliguria).

In addition to ascites, patients suffer from systemic manifestations: dyspepsia (heartburn, belching, anorexia) and severe nutritional status disorders. Severe weight loss occurs, contrasting with the massively distended abdomen.

Differential diagnosis of ascites

Although portal hypertension due to liver cirrhosis is the primary cause of ascites, a number of other diseases must be ruled out.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Pathogenesis of portosystemic anastomosis formation
• Instrumental diagnostic methods for esophageal varices
• Mechanisms of hypersplenism development in splenomegaly
• Laboratory criteria for distinguishing transudate from exudate
• Clinical manifestations of inferior vena cava compression syndrome

Other topics in the section "Liver, Biliary Tract, and Spleen"

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