Splenic Vein Thrombosis

Splenic vein thrombosis is occlusion of the splenic vein by clot, most often as a complication of pancreatic disease. It is the commonest cause of sinistral portal hypertension.

It occurs in 10% to 45% of patients with chronic pancreatitis, 5% to 10% of acute necrotising pancreatitis and a similar share of pancreatic cancer. Other causes are pancreatic surgery, splenectomy, myeloproliferative neoplasms, paroxysmal nocturnal haemoglobinuria, antiphospholipid syndrome and inherited thrombophilia.

Pathophysiology.

Inflammation and fibrosis, mass effect, and hypercoagulability produce stasis and endothelial injury (Virchow triad) in the vein as it runs behind the pancreas.

Often found at imaging with no symptoms. Others have left upper quadrant pain, splenomegaly, gastric variceal bleeding, thrombocytopenia from hypersplenism or the signs of the underlying pancreatic disease.

Red flags.

• Gastrointestinal bleeding.
• Extension into the portal or mesenteric veins.
• Splenic infarct.

Contrast CT (portal venous phase) or magnetic resonance venography shows a non-enhancing splenic vein and collaterals. Doppler ultrasound is a first screen. Endoscopy shows gastric varices. Look for a cause: imaging of the pancreas, full blood count, JAK2 mutation, antiphospholipid antibodies and flow cytometry for paroxysmal nocturnal haemoglobinuria.

Differential diagnosis.

• Tumour compression or invasion of the vein.
• Chronic portal vein thrombosis.
• Cirrhotic portal hypertension.
• Splenic arteriovenous fistula.

Treat the cause. Give anticoagulation for acute or subacute thrombosis, especially with extension into the portal vein or a thrombophilia, once varices are assessed and bleeding risk is acceptable. Chronic asymptomatic occlusion with no extension does not need anticoagulation. For variceal bleeding, inject cyanoacrylate endoscopically and consider splenectomy.

• Enoxaparin: 1 mg/kg subcutaneously every 12 hours for the first 5 to 7 days; maximum 100 mg for each dose; monitor platelets and anti-Xa level in renal impairment and obesity; reduce to 1 mg/kg once daily when creatinine clearance is under 30 mL/min.
• Rivaroxaban (continuation, no cirrhosis): 15 mg orally twice daily with food for 21 days, then 20 mg once daily to complete 3 to 6 months; maximum 30 mg daily in the first 21 days; monitor renal function and haemoglobin; avoid when creatinine clearance is under 15 mL/min, and avoid in moderate or severe hepatic impairment.
• Warfarin (alternative): target INR 2.0 to 3.0, started with enoxaparin cover for at least 5 days and until INR is in range for 24 hours; monitor INR; reduce the dose in hepatic impairment and older adults.

Splenectomy is considered for recurrent variceal bleeding.

Monitoring. Repeat imaging at 3 months; full blood count and renal function during anticoagulation.

Referral and escalation. Haematology for thrombophilia; pancreatic and hepatobiliary surgery.

Special groups. Avoid rivaroxaban in pregnancy; use enoxaparin.