Portal hypertension is a condition characterised by prolonged elevation of portal venous pressure (more than 30 cm saline).
Normal portal venous pressure is 10-15 cm saline or 7-10 mmHg.
Classification of portal hypertension
In presinusoidal extrahepatic portal hypertension, the obstruction is in the main portal vein.
In presinusoidal intrahepatic portal hypertension, the obstruction is usually in the portal tracts.
Another classification is based on the three levels in relation to hepatic sinusoids, where increased resistance to flow can occur.
Extrahepatic--e.g. portal vein thrombosis, splenic vein thrombosis.
Intrahepatic—e.g. schistosomiasis, non-cirrhotic portal fibrosis, primary biliary cirrhosis.
Extrahepatic—e.g. Budd-Chiari syndrome, congestive heart failure, constrictive pericarditis.
Intrahepatic—e.g. veno-occlusive disease affecting central hepatic venules.
Portal venous pressure is determined by:
Portal blood flow.
Portal vascular resistance.
Increased portal vascular resistance is almost always the main factor producing portal hypertension, irrespective of its cause. Increased portal vascular resistance leads to:
Reduction in the flow of portal blood to the liver.
Development of collateral vessels allowing portal blood to bypass the liver and enter systemic circulation. e Collateral vessel formation occurs particularly in the oesophagus, stomach, rectum, anterior abdominal wall and in the renal, lumbar, ovarian and testicular (spermatic) vasculature.
With the development of collateral vessels, initially most of the portal blood and later almost all of the entire portal blood is shunted directly to the systemic circulation, bypassing the liver.
Azygos and hemiazygos system
The sites of collateral circulation in the presence of intrahepatic portal vein obstruction
Causes of portal hypertension
I. Pre-hepatic and post-hepatic causes. II. Intra-hepatic causes.
A. Heart: Rise in atrial pressure, e.g. constrictive pericarditis. B. Inferior vena cava: Congenital webs, tumour invasion, thrombosis. C. Large hepatic veins: Thrombosis, webs, tumour invasion. D. Small hepatic veins: Veno-occlusive disease. E. Portal vein: Thrombosis, invasion or compression by tumours. F. Splenic vein: Thrombosis, invasion or compression by tumours. G. In¬creased blood flow: Idiopathic tropical splenomegaly, arteriovenous fistulae.
A. Post-sinusoidal causes: Veno-occlusive disease, alcoholic central hyaline sclerosis. B. Sinusoidal causes: Cirrhosis, acute alcoholic hepatitis, cytotoxic drugs, vitamin A intoxication. C. Pre-sinusoidal causes: Schistosomiasis, chronic active hepatitis, congenital hepatic fibrosis, sarcoidosis, toxins (vinyl chloride, copper, arsenic), idiopathic portal hypertension.
History and symptoms related to the aetiology of portal hypertension.
Past history of hepatitis.
Past history of abdominal inflammation (especially neonatal umbilical sepsis).
Prolonged use of oral contraceptives.
Haematemesis and melaena from variceal bleeding.
Stigmata of liver cell failure.
Foetor hepaticus is a musty odour of breath, resulting from portal-systemic shunting of blood which allows mercaptans to pass directly to the lungs.
Caput medusae—a number of prominent collateral vessels radiating from the umbilicus. Typical caput medusae is rare. Usually, only one or two veins are seen, especially in the epigastrium. The flow of blood is always away from the umbilicus.
In extrahepatic portal hypertension, prominent dilated veins are seen in the left flank.
A venous hum may be audible in the region of xiphoid process or umbilicus. This is due to the flow in collateral vessels. Very rarely, a thrill might be palpable at the site of maximum intensity of venous hum.
Cruveilhier-Baumgarten syndrome is the association of dilated abdominal wall veins and a loud venous hum at the umbilicus.
Splenomegaly is the single most important diagnostic sign of portal hypertension. A diagnosis of portal hypertension is unlikely if splenomegaly cannot be doeumented clinically, radiographically or by ultrasonography. Splenic size is usually less than 5 cm below costal margin. However, marked splenomegaly can occur in younger patients, those with macronodular cirrhosis and in extrahepatic portal hypertension. Hypersplenism is manifested as thrombocytopenia and leucopenia.
Liver size may be enlarged or shrunken.
Small, contracted, fibrotic liver is associated with very high portal venous pressure.
Soft liver suggests extrahepatic portal vein obstruction.
Firm liver suggests cirrhosis and hence intrahepatic portal hypertension.
Haemorrhoids may occur from dilation of rectal veins.
Ascites occurs partly due to portal hypertension and mainly due to liver cell failure. Portal hypertension determines the localisation of fluid to peritoneal cavity.
I. Barium swallow usually shows varices as filling defects in the lower third of oesophagus ('bag of worms appearance').
2. Upper gastrointestinal scopy.
Most reliable method.
Oesophageal varices are seen as blue rounded projections under submucosa.
"Cherry red spots" indicate impending rupture.
3. Ultrasonography detects.
Size of liver and spleen.
Size of portal vein and splenic vein.
Patency of portal vein and splenic vein.
4. Portal venography (splenoportovenogram) rarely done presently, can give information regarding the following:
Patency of portal vein and splenic vein.
Calibre of portal vein and splenic vein.
Sites of collaterals.
Varices at unusual sites.
The intrahepatic pattern of splenoportovenogram in cirrhosis is called tree in winter appearance.
5. Measurement of portal venous pressure by wedged hepatic venous pressure (WHVP) or transhepatic venous pressure.
Confirms portal hypertension.
Differentiates sinusoidal from presinusoidal forms.
6.Proctoscopy and barium enema for rectal and colonic varices.
7.Liver function tests for liver diseases.
Beta-blockers (propranolol, etc.) produce vasodilatation of both splanchnic arterial bed and portal venous system along with reduced cardiac output. Also reduce recurrence of variceal bleed.
Treatment of underlying disease.