Overview
Portal hypertension is an abnormal (pathological) increase in blood pressure within the portal venous system.
The portal system carries blood rich in nutrients to the liver. Veins from the spleen, pancreas, gallbladder, and the lower part of the GIT (gastrointestinal tract) drain into the portal vein, the main vessel of the portal system. The portal vein then divides into major branches to supply the liver tissue.
When the formation of scar tissues obstructs the flow of blood in the liver, as in the case of cirrhosis, the pressure within the portal vein is increased. This abnormal pressure causes the development of large, fragile veins within the oesophagus and the stomach and a subsequent rupture and bleeding, which may lead to fatal complications.
Key Facts
- Portal hypertension develops due to resistance to portal blood flow. Resistance may occur within the liver (intrahepatic), as in cirrhosis, outside the liver (prehepatic), or between the liver and heart (posthepatic).
- Identifying the point of resistance to portal blood flow allows the determination of the origin of portal hypertension.
- The primary cause is cirrhosis, which is the scarring of the liver due to continuous injury and healing of the liver tissue.
- Portal hypertension symptoms may not be specific at the onset.
- The major complication is bleeding from large swollen veins (varices), especially the veins within the oesophagus.
- Diagnosis is usually based on swollen abdomen (ascites) and swollen veins (varices).
- Treatment focuses on decreasing the pressure in the portal system and managing complications, particularly bleeding from ruptured vessels.
Categories of Portal Hypertension
Depending on where the resistance to blood flow occurs, portal hypertension can be divided into the following types:
Prehepatic Portal Hypertension
An increase in blood flow to the portal vein or an obstruction within this vein gives rise to prehepatic portal hypertension. Thrombosis (blockage in vessels by blood clots) and the abnormal narrowing of the portal vein (stenosis) due to a tumour present within the vein are responsible for this type of hypertension.
Ascites rarely occur in this condition because collateral circulation is immediately formed to decrease the pressure.
Intrahepatic Portal Hypertension
This type of hypertension mostly results from liver scarring (cirrhosis). Consequently, conditions like chronic hepatitis and primary biliary cholangitis (a chronic autoimmune disease of the bile ducts) give rise to intrahepatic portal hypertension.
Posthepatic Portal Hypertension
It occurs between the liver and the heart. Obstruction at the heart level may be caused by an elevation of the pressure in the heart’s atria, as in constrictive pericarditis, which is the thickening of the heart’s covering. Similarly, it can occur at the inferior vena cava level due to blood clot formation (thrombosis) or narrowing (stenosis) of the vessel.
Symptoms and Diagnosis
Symptoms
A decrease in blood flow causes symptoms of portal hypertension through the liver and increased pressure within the portal venous system.
Symptoms may include:
- Gastrointestinal bleeding: There may be vomiting of blood or the presence of blood in stools as a result of ruptured blood vessels within the oesophagus or stomach.
- Ascites: Fluid accumulation in the abdominal cavity
- Caput medusa: A visible network of veins may be seen around the umbilical region.
- Splenomegaly: Enlargement of the spleen
- Hepatic encephalopathy: is the loss of brain function due to liver damage and dysfunction. It is characterized by confusion and lethargy.
- Oedema: Swelling of the legs may be seen due to fluid retention.
- Jaundice: Yellowing of the sclera (white of the eyes) and skin.
Diagnosis
The presence of ascites, varices, or both can confirm this clinical syndrome, and the doctor may not need to perform any other diagnostic tests for confirmation.
Laboratory tests, imaging, elastography, and endoscopy may be used for diagnosis.
Laboratory Tests
Full blood count (FBC), liver function test and coagulation studies ( prothrombin time and partial thromboplastin time) indicate impaired liver function.
Imaging Tests
Duplex Doppler Ultrasonography of the upper abdomen and liver is usually the first imaging test recommended by a doctor. This test shows the speed and direction of blood flow through the portal vein and a detailed image of the blood vessels that make up the portal venous system, thereby revealing the conditions of these vessels.
MRI and CT
MRI (magnetic resonance imaging) and CT (computed tomography) procedures can be employed when there is still uncertainty after ultrasonography findings.
Elastography
It is used to measure the elasticity of the liver and surrounding tissues. Stiffness suggests portal hypertension.
Endoscopic Examination
Endoscopic diagnosis is mainly made when gastrointestinal bleeding occurs. Endoscopy can provide a conclusive diagnosis of varices (swollen veins).
Causes and Prevention
Causes
The leading cause of portal hypertension is scarring of the liver tissue (cirrhosis), which results from various clinical conditions, such as viral hepatitis, fatty liver disease, and nonalcoholic fatty liver disease.
Other causes may be classified based on the level at which resistance to blood flow is offered.
They include:
Prehepatic Causes
- Portal or splenic vein thrombosis
- Splenomegaly (enlargement of the spleen)
Intrahepatic Causes
- Primary sclerosing cholangitis (bile duct scarring)
- Chronic pancreatitis (long-term inflammation of the pancreas)
- Schistosomiasis
Posthepatic Causes
- Hepatic thrombosis
- Constrictive pericarditis
- Inferior vena cava thrombosis
- Inferior vena cava stenosis
Prevention
Prevention should aim to reduce the risk of cirrhosis, the primary cause of portal hypertension.
Some tips for the prevention of cirrhosis include:
- Eating a healthy diet: Plant-based diet full of fruits and vegetables is recommended.
- Exercising regularly
- Avoiding alcohol misuse
- Taking only prescribed medications
- Getting the vaccine for hepatitis
Typical Treatments
The treatment procedures for portal hypertension focus on preventing complications or managing any already present.
They include:
- Endoscopic therapy: It is the first line of treatment for bleeding vessels. A treatment called sclerotherapy is used to stop bleeding in the liver, while banding (the use of rubber bands) helps stop bleeding in enlarged veins of the digestive system.
- Medications: Beta-blockers like propranolol can reduce blood pressure in the portal vein. They can also be used to stop bleeding from swollen vessels of the gastrointestinal tract. Additionally, diuretics are used to reduce the fluid level of the body in patients with ascites.
Conclusion
Portal hypertension is a clinical syndrome characterized by an increase in the pressure within the veins of the portal system.
Cirrhosis is considered the primary cause of this clinical condition. Thus, preventive measures focus on decreasing a person’s risk of cirrhosis.
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