What is the recommended anticoagulation therapy for portal vein thrombosis?

Anticoagulation for Portal Vein Thrombosis

Anticoagulation therapy is recommended for patients with symptomatic portal vein thrombosis (PVT), recent (<6 months) occlusive or partially occlusive (>50%) thrombosis of the main portal vein, or progressive thrombosis for a minimum of 6 months. 1

Indications for Anticoagulation

Definite Indications

• Symptomatic PVT 1
• Recent (<6 months) occlusive or partially occlusive (>50%) thrombosis of main portal vein 1
• Progressive thrombosis on follow-up imaging 1
• Liver transplant candidates 1, 2
• Thrombus involving mesenteric vessels 1, 2
• Multiple vascular bed involvement 1, 2
• Inherited thrombophilia 1, 2

Consider Observation Rather Than Anticoagulation

• Recent (<6 months) thrombosis involving only intrahepatic portal vein branches 1
• <50% occlusion of main portal vein, splenic vein, or mesenteric veins 1

Anticoagulation Not Recommended

• Chronic (>6 months) PVT with complete occlusion with collateralization (cavernous transformation) 1

Pre-Anticoagulation Assessment

• Evaluate for presence of varices and ensure adequate management prior to initiating anticoagulation 1
• Endoscopic variceal screening is warranted if patients are not already on nonselective beta-blocker therapy 1
• Avoid delays in initiating anticoagulation as this decreases odds of portal vein recanalization 1, 2

Anticoagulation Options

For Child-Pugh A or B Cirrhosis

• Direct oral anticoagulants (DOACs) 1, 2
• Low molecular weight heparin (LMWH) 1, 2
• Vitamin K antagonists (VKAs) with target INR 2-3 1, 2

For Child-Pugh C Cirrhosis

• LMWH alone 1
• LMWH as bridge to VKA in patients with normal baseline INR 1

Monitoring and Duration

• Cross-sectional imaging every 3 months to assess response to treatment 1, 2
• Continue anticoagulation for a minimum of 6 months 1
• If clot regresses, continue anticoagulation until transplantation or at least until clot resolution in non-transplantation patients 1
• Regular reassessment of bleeding risk (e.g., at 6-month intervals) 1
• Consider withdrawing anticoagulation in the event of active bleeding or significant increase in bleeding risk 1

Expected Outcomes

• Complete recanalization rates with anticoagulation: 33-75% 2, 3
• Early initiation of anticoagulation is associated with higher recanalization rates 2, 4
• Specific recanalization rates by vessel: 38-39% for portal vein, 54-80% for splenic vein, 61-73% for superior mesenteric vein 2

Special Considerations

Thrombocytopenia

• Anticoagulation should not be withheld in patients with moderate thrombocytopenia secondary to advanced liver disease 1
• Case-by-case decision when platelet count is <50 × 10^9/L, based on site and extent of thrombosis, risk of thrombus extension, and presence of active bleeding/additional bleeding risk factors 1

Interventional Approaches

• Portal vein revascularization with transjugular intrahepatic portosystemic shunting (TIPS) may be considered for selected patients with additional indications such as refractory ascites or variceal bleeding 1
• TIPS may also be considered for liver transplantation candidates 1

Common Pitfalls and Caveats

• Failure to screen for varices before initiating anticoagulation may increase bleeding risk
• Delaying anticoagulation reduces chances of successful recanalization 1, 2
• No patient failing to recanalize within first 6 months of therapy is likely to recanalize later 2
• Major bleeding complications are relatively rare (1-2%) when appropriate prophylaxis for gastrointestinal bleeding is implemented 2
• Discontinuation of anticoagulation may lead to PVT recurrence 4