Clinical Manifestations Of Cirrhosis Portal Hypertension
- The range of clinical features in cirrhosis varies widely, from an asymptomatic state to progressive liver failure and death. The onset of the disease is insidious.
- In general, the features of cirrhosis are more marked in the alcoholic form than in other varieties.
- These include weakness, fatiguability, weight loss, anorexia, muscle wasting, and low-grade fever due to hepatocellular necrosis or some latent infection.
- Advanced cases develop a number of multisystem complications which have been discussed under hepatic failure. However, portal hypertension, the commonest complication of cirrhosis and its sequelae are discussed below.
Read And Learn More: Systemic Pathology Notes
Portal Hypertension Definition
- An increase in pressure in the portal system usually follows obstruction to the portal blood flow anywhere along its course.
- Portal veins have no valves and thus obstruction anywhere in the portal system raises the pressure in all the veins proximal to the obstruction.
- However, unless proven otherwise, portal hypertension means obstruction to the portal blood flow by cirrhosis of the liver.
- The normal portal venous pressure is quite low (10-15 mm saline). Portal hypertension occurs when the portal pressure is above 30 mm saline.
- Measurement of intrasplenic pressure reflects pressure in the splenic vein the percutaneous transhepatic pressure provides a measure of pressure in the main portal vein, and wedged hepatic venous pressure represents sinusoidal pressure.
- Measurement of these pressures helps in localising the site of obstruction and classifying portal hypertension.
Portal Hypertension Classification
- Based on the site of obstruction to portal venous blood flow, portal hypertension is categorised into 3 main types—intrahepatic, posthepatic and prehepatic.
- Rare cases of idiopathic portal hypertension showing non-cirrhotic portal fibrosis are encountered as discussed above.
1. Intrahepatic portal hypertension: Cirrhosis is by far the commonest cause of portal hypertension.
- Other less frequent intrahepatic causes are metastatic tumours, non-cirrhotic nodular regenerative conditions, hepatic venous obstruction (Budd-Chiari syndrome), venoocclusive disease, schistosomiasis, diffuse granulomatous diseases and extensive fatty change.
- In cirrhosis and other conditions, there is an obstruction to the portal venous flow by fibrosis, thrombosis and pressure by regenerative nodules. About 30-60% patients of with cirrhosis develop significant portal hypertension.
Major causes of portal hypertension.
1. Intrahepatic
- Cirrhosis
- Metastatic tumours
- Budd-Chiari syndrome
- Hepatic veno-occlusive disease
- Diffuse granulomatous diseases
- Extensive fatty change
2. Posthepatic
- Congestive heart failure
- Constrictive pericarditis
- Hepatic veno-occlusive disease
- Budd-Chiari syndrome
3. Prehepatic
- Portal vein thrombosis
- Neoplastic obstruction of portal vein
- Myelofibrosis
- Congenital absence of portal vein
2. Posthepatic portal hypertension: This is uncommon and results from obstruction to the blood flow through a hepatic vein into the inferior vena cava.
- The causes are neoplastic occlusion and thrombosis of the hepatic vein or of the inferior vena cava (including Budd-Chiari syndrome).
- Prolonged congestive heart failure and constrictive pericarditis may also cause portal hypertension by transmitting elevated pressure through the hepatic vessels into the portal vein.
3. Prehepatic portal hypertension: Blockage of portal flow before portal blood reaches the hepatic sinusoids results in prehepatic portal hypertension.
- Such conditions are thrombosis and neoplastic obstruction of the portal vein before it ramifies in the liver, myelofibrosis, and congenital absence of the portal vein.
Major Sequelae of Portal Hypertension
- Irrespective of the mechanisms involved in the pathogenesis of portal hypertension, there are 4 major clinical consequences ascites, varices (collateral channels or portosystemic shunts), plenomegaly and hepatic encephalopathy.
1. Ascites: Ascites is the accumulation of an excessive volume of fluid within the peritoneal cavity. It frequently accompanies cirrhosis and other diffuse liver diseases.
The development of ascites is associated with haemodilution, oedema and decreased urinary output.
- Ascitic fluid is generally transudate with a specific gravity of 1.010, protein content below 3 gm/dl and electrolyte concentrations like those of other extracellular fluids.
- It may contain a few mesothelial cells and mononuclear cells. The presence of neutrophils is suggestive of secondary infection and red blood cells in ascitic fluid point to disseminated intra-abdominal cancer.
- However, some cases of ascites may develop serious complications of spontaneous bacterial peritonitis characterised by spontaneous infection of the ascitic fluid without any intra-abdominal infection
Pathogenesis: The ascites become clinically detectable when more than 500 ml of fluid has accumulated in the peritoneal cavity.
- The mechanisms involved in its formation were discussed. Briefly, the systemic and local factors favouring ascites formation are under
1. Systemic Factors
- Decreased plasma colloid oncotic pressure There is hypoalbuminaemia from impaired hepatic synthesis of plasma proteins including albumin, as well as from loss of albumin from the blood plasma into the peritoneal cavity.
- Hypoalbuminaemia, in turn, causes reduced plasma oncotic pressure and leads to loss of water into extravascular space.
- Hyperaldosteronism In cirrhosis, there is increased aldosterone secretion by the adrenal gland, probably due to reduced renal blood flow, and impaired hepatic metabolism and excretion of aldosterone.
- Impaired renal excretion Reduced renal blood flow and excessive release of antidiuretic hormone results in renal retention of sodium and water and impaired renal excretion.
2. Local Factors
- Increased portal pressure Portal venous pressure is not directly related to ascites formation but portal hypertension in combination with other factors contributes to the formation and localisation of fluid retention in the peritoneal cavity.
- Increased hepatic lymph formation Obstruction of the hepatic vein such as in Budd-Chiari syndrome and increased intra-sinusoidal pressure found in cirrhotic patients stimulates hepatic lymph formation that oozes through the surface of the liver.
2. Varices (Collateral Channels Or Porto-Systemic Shunts): As a result of rise in portal venous pressure and obstruction in the portal circulation within or outside the liver, the blood tends to bypass the liver and return to the heart by the development of portosystemic collateral channels (or shunts or varices).
- These varices develop at sites where the systemic and portal circulations have common capillary beds. The principal sites are as under
1. Oesophageal varices The development of oesophagogastric varices which is frequently manifested by massive haematemesis is the most important consequence of portal hypertension.
2. Haemorrhoids Development of collaterals between the superior, middle and inferior haemorrhoidal veins resulting in haemorrhoids is another common accompaniment.
- Bleeding from haemorrhoids is usually not as serious a complication as haematemesis from oesophageal varices.
3. Caput medusae Anastomoses between the portal and systemic veins may develop between the hilum of the liver and the umbilicus along the paraumbilical plexus of veins resulting in abdominal wall collaterals.
- These appear as dilated subcutaneous veins radiating from the umbilicus and are termed caput-medusae (named after the snake-haired Medusa).
4. Retroperitoneal anastomoses In the retroperitoneum, portocaval anastomoses may be established through the veins of Retzius and the veins of Sappey.
3. Splenomegaly The enlargement of the spleen in prolonged portal hypertension is called congestive splenomegaly The spleen may weigh 500-1000 gm and is easily palpable.
- The spleen is larger in young people and in macronodular cirrhosis than in micronodular cirrhosis.
4. Hepatic Encephalopathy Porto-systemic venous shunting may result in a complex metabolic and organic syndrome of the brain characterised by disturbed consciousness, neurologic signs and flapping tremors.
- Hepatic encephalopathy is particularly associated with advanced hepatocellular diseases such as cirrhosis.
- The ultimate causes of death in cirrhosis are hepatic coma, massive gastrointestinal haemorrhage from oesophageal varices (a complication of portal hypertension), intercurrent infections, hepatorenal syndrome and development of hepatocellular carcinoma.
Cirrhosis
- Cirrhosis is a diffuse liver disease characterised by the effacement of normal lobular architecture, formation of nodules separated by fibrous septa and alternate areas of hepatocellular necrosis and regenerative nodules.
- There are 3 morphologic types of cirrhosis—micronodular, macronodular and mixed.
- Based on aetiology, major forms are alcoholic, postnecrotic, biliary, and haemochromatosis.
- Alcoholic cirrhosis evolves through preceding sequential stages of steatosis and alcoholic hepatitis.
- The most common etiologic factor for postnecrotic cirrhosis is preceding chronic viral hepatitis with hepatitis B or C.
- A few variant forms are non-alcoholic fatty liver disease, cirrhosis in autoimmune hepatitis, non-cirrhotic portal fibrosis etc.
- Advanced cases of cirrhosis develop portal hypertension and its sequelae.
- Portal hypertension occurs when the portal pressure is above 30 mm saline (normal 10-15 mm saline).
- Based on the site of obstruction to portal venous blood flow, portal hypertension is categorised into intrahepatic (for example cirrhosis), posthepatic (for example CHF) and prehepatic (for example portal vein thrombosis).
- Major clinical consequences of portal hypertension are ascites, varices (collateral channels or portosystemic shunts), splenomegaly and hepatic encephalopathy.
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