Chronic Portal Vein Thrombosis

Chronic portal vein thrombosis is long standing occlusion of the main portal vein or its branches, with fibrosis and the formation of collateral veins (cavernous transformation). It causes non-cirrhotic portal hypertension in patients with normal liver function.

It is the commonest cause of extrahepatic portal hypertension and variceal bleeding in children in many regions. Causes are cirrhosis, myeloproliferative neoplasms (JAK2), prothrombotic states (factor V Leiden, prothrombin gene variant, antiphospholipid syndrome, paroxysmal nocturnal haemoglobinuria), abdominal sepsis, umbilical vein catheterisation in neonates, pancreatitis and malignancy.

Pathophysiology.

Occlusion shifts portal blood through collateral veins around the thrombus, causing portal hypertension. Collaterals compress the bile duct to cause portal cholangiopathy.

Variceal haemorrhage, splenomegaly with thrombocytopenia (hypersplenism), growth failure in children, abdominal pain, portal cholangiopathy with jaundice and biliary pain, and minimal encephalopathy. Ascites is less common.

Red flags.

• Haematemesis or melaena.
• Intestinal ischaemia from mesenteric extension.
• Jaundice with cholangitis.

Doppler ultrasound shows absent flow in the main portal vein with a cavernous collateral network. CT or magnetic resonance venography defines extension into the splenic and superior mesenteric veins and the status of the liver. Endoscopy shows oesophageal, gastric and ectopic varices. Search for the cause: full blood count, JAK2 V617F, thrombophilia screen, antiphospholipid antibodies and flow cytometry for paroxysmal nocturnal haemoglobinuria. Elastography excludes cirrhosis.

Differential diagnosis.

• Cirrhosis with portal vein thrombosis.
• Hepatic venous outflow obstruction.
• Idiopathic non-cirrhotic portal hypertension.
• Schistosomiasis.
• Tumour invasion of the portal vein.

Prevent variceal bleeding with non-selective beta blockers or band ligation, and treat bleeding promptly. Anticoagulation is given when there is a prothrombotic state, extension toward the mesenteric veins, or recent recurrence of thrombosis. Surgical shunt (mesenteric left portal vein Rex shunt in children, or splenorenal shunt) is for failed endoscopic control and symptomatic hypersplenism.

• Carvedilol: 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.
• Propranolol (alternative): 20 to 40 mg orally twice daily, increased to a resting heart rate of 55 to 60/min; maximum 160 mg daily (80 mg daily with ascites); monitor blood pressure and heart rate; avoid in asthma.
• Enoxaparin: 1 mg/kg subcutaneously every 12 hours for 5 to 7 days then oral anticoagulant; 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.
• Rivaroxaban (no cirrhosis): 20 mg orally once daily with food for 6 to 12 months or indefinitely with a persistent thrombophilia; maximum 20 mg daily; monitor renal function and haemoglobin; avoid when creatinine clearance is under 15 mL/min and in moderate or severe hepatic impairment.

Treat portal cholangiopathy with endoscopic stenting and, in refractory cases, a shunt.

Monitoring. Endoscopy to confirm eradication of varices every 3 to 6 months until cleared, then yearly; ultrasound and blood counts each year.

Referral and escalation. Hepatology, haematology and hepatobiliary surgery.

Special groups. Children need weight based dosing and early Rex shunt assessment.