Causes of Oesophageal Varices Beyond Portal Hypertension
While portal hypertension is the predominant cause of oesophageal varices, they can develop from superior vena cava (SVC) obstruction causing "downhill varices," splenic or portal vein thrombosis without cirrhosis, and in specific cardiac conditions like Fontan circulation.
Non-Portal Hypertension Causes
Superior Vena Cava Obstruction ("Downhill Varices")
The most important non-portal hypertension cause is SVC obstruction, which creates varices through an entirely different mechanism 1, 2. These "downhill varices" result from:
- Obstruction of the SVC and azygous venous system causing blood to drain downward through oesophageal veins
- Key distinguishing feature: Varices located in the upper and middle oesophagus (not lower oesophagus like portal hypertension varices)
- Common causes 2:
- Hemodialysis access in end-stage renal disease patients
- Mediastinal malignancies
- Thrombosis of central venous catheters
Clinical pitfall: These patients will have evidence of SVC syndrome (facial/upper extremity swelling, dilated chest wall veins) rather than signs of liver disease. The varices appear only in upper/middle oesophagus on endoscopy, which should immediately alert you to look for SVC obstruction rather than assuming liver disease.
Splenic or Portal Vein Thrombosis Without Cirrhosis
Isolated splenic or portal vein thrombosis can cause varices in the absence of cirrhosis or underlying liver disease 1:
- Splenic vein thrombosis most commonly from pancreatitis causes interruption of splenic venous outflow
- Results in isolated gastric varices (and can extend to oesophageal varices) without cirrhosis
- Portal vein occlusion without cirrhosis develops both oesophageal and gastric varices
- These are typically isolated gastric varices rather than gastroesophageal varices
Key mechanism: The thrombosis blocks normal venous drainage, forcing blood through portosystemic collateral veins including oesophageal varices, despite normal liver architecture.
Fontan-Type Circulation
In patients with Fontan surgery (congenital heart disease repair), varices develop through unique haemodynamics 3:
- Elevated superior vena cava and pulmonary pressures create veno-venous communications
- Causes diffuse dilatation of upper venous plexus
- Results in "downhill varices" in upper oesophagus even without liver fibrosis or cirrhosis
- Can also develop true portal hypertension-related varices from Fontan-associated liver disease (FALD)
Important distinction: These patients may have both types of varices simultaneously - downhill varices from elevated systemic venous pressure AND traditional varices if they've developed FALD with portal hypertension 3.
Idiopathic Non-Cirrhotic Portal Hypertension (INCPH)
While technically involving portal hypertension, INCPH causes varices without cirrhosis 4:
- Portal venous obliteration from thrombophilia, immunological disorders, specific medications (azathioprine, didanosine), or HIV infection
- Diagnosis requires: Signs of portal hypertension (splenomegaly, varices, ascites) + exclusion of cirrhosis on biopsy + patent portal/hepatic veins + exclusion of other chronic liver diseases
- Patients often have normal liver function at presentation
- Clue: Low liver stiffness on elastography (<12 kPa) despite portal hypertension signs
Diagnostic Approach
When encountering oesophageal varices:
Assess varix location on endoscopy:
- Upper/middle oesophagus only → Consider SVC obstruction or Fontan circulation
- Lower oesophagus → Portal hypertension (cirrhotic or non-cirrhotic)
Look for SVC syndrome signs: Facial swelling, upper extremity oedema, dilated chest wall veins
Evaluate for liver disease: If absent, obtain contrast-enhanced CT or MRI to identify portal/splenic vein patency and assess for thrombosis 1
Check cardiac history: Fontan surgery or congenital heart disease
If portal hypertension suspected without cirrhosis: Screen for thrombophilia, autoimmune conditions, medication history, and consider liver biopsy to exclude INCPH 4
Critical point: The treatment differs fundamentally - downhill varices require addressing the underlying SVC obstruction rather than portal pressure reduction 2. Without treating the primary cause, patients face recurrent potentially fatal bleeding.