Portal hypertension - Causes

The main causes of portal hypertension are:

Prehepatic (subhepatic) portal hypertension.

1. Increased portal venous blood flow:
   1. arteriovenous fistula;
   2. splenomegaly not associated with liver disease;
   3. portal vein cavernomatosis.
2. Thrombosis or occlusion of the portal or splenic veins.

Intrahepatic portal hypertension

1. Liver diseases.
   1. Spicy:
      1. alcoholic hepatitis;
      2. alcoholic fatty liver;
      3. fulminant viral hepatitis.
   2. Chronic:
      1. alcoholic liver disease;
      2. chronic active hepatitis;
      3. primary biliary cirrhosis;
      4. viral cirrhosis;
      5. Wilson-Konovalov disease;
      6. hemochromatosis;
      7. alpha1-antitrypsin deficiency;
      8. cryptogenic cirrhosis;
      9. idiopathic portal hypertension;
      10. liver diseases caused by arsenic, vinyl chloride, copper salts;
      11. congenital liver fibrosis;
      12. schistosomiasis;
      13. sarcoidosis;
      14. obliteration of intrahepatic branches of the hepatic veins associated with treatment with cytostatics;
      15. metastatic carcinoma;
      16. nodular regenerative hyperplasia of the liver;
      17. focal nodular hyperplasia.

Posthepatic portal hypertension

1. Diseases of the hepatic venules and veins, inferior vena cava:
   1. congenital membranous occlusion of the inferior vena cava;
   2. veno-occlusive disease;
   3. hepatic vein thrombosis (Budd-Chiari disease and syndrome);
   4. inferior vena cava thrombosis;
   5. developmental defects of the inferior vena cava;
   6. tumor compression of the inferior vena cava and hepatic vein.
2. Heart diseases:
   1. cardiomyopathy;
   2. heart disease with valve damage;
   3. constrictive pericarditis.

Infections

In neonates, extrahepatic presinusoidal hypertension may be caused by omphalitis, including that caused by umbilical vein catheterization. The infection spreads through the umbilical vein to the left branch of the portal vein and then to its main trunk. In older children, acute appendicitis and peritonitis are the cause.

Portal vein occlusion is particularly common in India, accounting for 20-30% of all variceal bleeding cases. In neonates, it may be due to dehydration and infection.

Portal vein obstruction can develop in ulcerative colitis and Crohn's disease.

It can also be a complication of a bile duct infection, such as gallstones or primary sclerosing cholangitis.

Surgical interventions

Portal and splenic vein obstruction often develops after splenectomy, especially if the platelet count was normal before surgery. Thrombosis extends from the splenic vein to the main trunk of the portal vein. It is especially common in myeloid metaplasia. A similar sequence of events is observed in thrombosis of a surgically created portosystemic shunt.

Portal vein thrombosis can develop as a complication of major and complex operations on the liver and bile ducts, for example, when eliminating a stricture or removing a common bile duct cyst.

Injuries

Portal vein injury is sometimes seen in car accidents or penetrating knife wounds. Portal vein rupture is fatal in 50% of cases, and the only way to stop bleeding is to ligate the vein.

Conditions accompanied by increased thrombus formation

In adults, the hypercoagulable state often causes portal vein thrombosis. It is more often observed in myeloproliferative diseases, which can be latent. At autopsy, thrombotic changes are often detected macroscopically and histologically in patients with portal hypertension and myeloproliferative disease. Portal vein thrombosis is accompanied by ascites and esophageal varices.

Portal vein thrombosis may complicate the course of congenital protein C deficiency.

Tumor invasion and compression

A classic example of a tumor that can grow into or compress the portal vein is hepatocellular carcinoma. Portal vein block can also be caused by cancer of the pancreas (usually its body) or other structures adjacent to the vein. In chronic pancreatitis, the splenic vein is often obstructed; the portal vein is rarely affected (5.6%).

Congenital anomalies

Congenital obstruction of any part of the right and left vitelline veins, from which the portal vein is formed, is possible. The portal vein may be absent altogether, and blood from the internal organs flows into the central veins, mainly into the inferior vena cava. Venous collaterals do not form in the liver gates.

Congenital anomalies of the portal vein are usually combined with other congenital malformations.

Cirrhosis

Portal vein thrombosis is a rare complication of liver cirrhosis. The most common cause is hepatocellular carcinoma that develops against the background of cirrhosis. Another mechanism of portal vein obstruction is thrombocytosis after splenectomy. Mural thrombi found in the lumen of the portal vein at autopsy apparently form in the terminal state. There is a risk of overdiagnosis of thrombosis, since the portal vein is sometimes not filled with visualization methods, which is associated with redistribution of blood into large collaterals or into an enlarged spleen.

Other reasons

In very rare cases, portal vein thrombosis is associated with pregnancy, as well as with long-term use of oral contraceptives, especially in older women.

Portal vein block may be associated with systemic venous disease, especially migratory thrombophlebitis.

In retroperitoneal fibrosis, dense fibrous tissue can compress the portal vein.

Unknown causes

In about half of patients, after a thorough examination, the cause of portal vein obstruction remains unknown. Some of them are found to have concomitant autoimmune diseases, such as hypothyroidism, diabetes mellitus, pernicious anemia, dermatomyositis, rheumatoid arthritis. In some cases, obstruction develops after undiagnosed infections of the abdominal organs, such as appendicitis or diverticulitis.

1. Spicy:
   1. alcoholic hepatitis;
   2. alcoholic fatty liver;
   3. fulminant viral hepatitis.
2. Chronic:
   1. alcoholic liver disease;
   2. chronic active hepatitis;
   3. primary biliary cirrhosis;
   4. viral cirrhosis;
   5. Wilson-Konovalov disease;
   6. hemochromatosis;
   7. alpha1-antitrypsin deficiency;
   8. cryptogenic cirrhosis;
   9. idiopathic portal hypertension;
   10. liver diseases caused by arsenic, vinyl chloride, copper salts;
   11. congenital liver fibrosis;
   12. schistosomiasis;
   13. sarcoidosis;
   14. obliteration of intrahepatic branches of the hepatic veins associated with treatment with cytostatics;
   15. metastatic carcinoma;
   16. nodular regenerative hyperplasia of the liver;
   17. focal nodular hyperplasia.
3. Diseases of the hepatic venules and veins, inferior vena cava:
   1. congenital membranous occlusion of the inferior vena cava;
   2. veno-occlusive disease;
   3. hepatic vein thrombosis (Budd-Chiari disease and syndrome);
   4. inferior vena cava thrombosis;
   5. developmental defects of the inferior vena cava;
   6. tumor compression of the inferior vena cava and hepatic vein.
4. Heart diseases:
   1. cardiomyopathy;
   2. heart disease with valve damage;
   3. constrictive pericarditis.

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