Portal Vein Stenosis

Portal vein stenosis is narrowing of the main portal vein or its branches that raises portal pressure and reduces hepatopetal flow. It is most often a complication of liver transplantation or hepatobiliary surgery.

After liver transplantation it occurs in 1% to 3% of adult recipients and up to 10% of children. Other causes are pancreatitis, tumour compression or invasion, previous thrombosis, radiation and anastomotic fibrosis.

Pathophysiology.

Anastomotic size mismatch, surgical technique, kinking, and fibrosis narrow the lumen. Flow limitation causes portal hypertension, thrombosis, ascites and graft dysfunction.

Ascites, splenomegaly, thrombocytopenia, variceal bleeding, portal hypertensive gastropathy, abnormal liver tests and graft dysfunction. Some patients have no symptoms.

Red flags.

• Variceal bleeding.
• Acute thrombosis with graft dysfunction.
• Refractory ascites.

Doppler ultrasound shows a velocity over 125 cm/s at the stricture, a velocity ratio over 3 with the pre-stenotic segment, and slow pre-stenotic flow. CT or magnetic resonance angiography confirms the stenosis. Direct portography with a pressure gradient over 5 mmHg (or over 3 mmHg in children) across the stricture confirms haemodynamic significance. Endoscopy assesses varices.

Differential diagnosis.

• Portal vein thrombosis.
• Hepatic artery thrombosis.
• Hepatic venous outflow obstruction.
• Recurrent cirrhosis.
• Tumour recurrence.

Percutaneous or transjugular balloon venoplasty, with a stent if venoplasty fails or the stenosis recurs, is the first treatment. Surgery (revision, interposition graft or shunt) is for failure. Give antithrombotic treatment after the procedure and prophylaxis against variceal bleeding.

• Enoxaparin: 1 mg/kg subcutaneously every 12 hours for 5 to 7 days after stenting; maximum 100 mg for each dose; monitor platelets and anti-Xa level; reduce to 1 mg/kg once daily when creatinine clearance is under 30 mL/min.
• Aspirin after stenting: 75 to 100 mg orally once daily for 3 to 6 months; maximum 100 mg daily; monitor bleeding and platelets; avoid with active bleeding and varices that are not treated.
• Carvedilol (variceal prophylaxis): 6.25 mg orally daily for 3 days then 12.5 mg daily; maximum 12.5 mg daily (25 mg daily without ascites); monitor blood pressure and heart rate; hold when systolic pressure is under 90 mmHg, and avoid in refractory ascites.

Band ligation is used when varices are large or have bled.

Monitoring. Doppler at 1 week, 1 month, 3 months and every 6 months; platelets and liver tests with each review.

Referral and escalation. Interventional radiology, transplant hepatology and surgery.

Special groups. Children need weight based enoxaparin dosing and paediatric venoplasty expertise.