What are the causes of splanchnic/portal vein thrombosis (SPVT)?

Causes of Splanchnic/Portal Vein Thrombosis (SPVT)

SPVT results from a combination of local and systemic risk factors, with the etiology being multifactorial in the majority of cases—prothrombotic factors are identified in up to 84% of Budd-Chiari syndrome patients and 42% of portal vein thrombosis patients. 1

Local Risk Factors

Liver Disease and Malignancy

• Liver cirrhosis is the most common cause of portal vein thrombosis, accounting for over half of all cases, particularly in advanced disease with decreased portal flow velocity below 15 cm/s 2
• Hepatocellular carcinoma causes portal vein thrombosis in 20-30% of patients at diagnosis and represents a major local risk factor 1
• Other abdominal malignancies, particularly pancreatic carcinoma, are common causes of SPVT 1

Inflammatory and Infectious Conditions

• Pancreatitis is a significant local risk factor for SPVT development 1
• Intra-abdominal infections and inflammatory conditions (inflammatory bowel disease, diverticulitis, appendicitis, cholecystitis) increase thrombosis risk 1, 2

Surgical and Traumatic Causes

• Abdominal surgery, particularly splenectomy, is a well-established risk factor 1
• Liver transplantation and surgical portosystemic shunting can precipitate SPVT 2
• In neonates and children, umbilical vein catheterization and omphalitis are age-specific causes 1, 2

Systemic Risk Factors

Inherited Thrombophilias

• Factor V Leiden mutation increases SPVT risk by 4-11 fold 2
• Prothrombin G20210A mutation increases risk by 4-5 fold 2
• Antithrombin deficiency (prevalence 0-5% in SPVT patients) 1
• Protein C and protein S deficiencies contribute to thrombosis risk 1

Acquired Thrombophilias

• Myeloproliferative neoplasms (polycythemia vera, essential thrombocythemia) are predominant systemic risk factors 1, 3
• JAK2 V617F mutation is detected in approximately 20-40% of SPVT patients even without overt myeloproliferative disorders 1
• Paroxysmal nocturnal hemoglobinuria (PNH) has high propensity for splanchnic venous thrombosis 1
• Antiphospholipid syndrome increases SPVT risk 2

Hormonal Factors

• Oral contraceptive use is linked to SPVT development 1
• Hormone replacement therapy and pregnancy increase thrombosis risk 1, 2

Multifactorial Nature

The etiology is frequently multifactorial, with 46% of Budd-Chiari syndrome patients and 10% of portal vein thrombosis patients having two or more prothrombotic factors. 1, 2

• In patients with a local risk factor, an additional prothrombotic factor is found in 36% of cases 1, 2
• Over 60% of patients with inherited thrombophilia have an additional risk factor 1, 2
• In 18% of Budd-Chiari syndrome patients, three or more risk factors are present 1

Geographic Variations

• In Western countries, myeloproliferative disorders and inherited thrombophilias predominate 2
• In Asian countries, Behçet's disease, inferior vena cava webs (membranous obstruction), and hydatid cysts are more prevalent causes 1, 2

Emerging Risk Factors

• Obesity, metabolic syndrome, and NASH cirrhosis are increasingly recognized as independent risk factors for portal vein thrombosis 2
• Non-selective beta-blockers may increase PVT risk in cirrhotic patients, though this association may be confounded by more severe portal hypertension 2

Common Pitfalls

A critical pitfall is failing to recognize the multifactorial nature of SPVT—even when a local cause like cirrhosis is identified, systemic prothrombotic factors should still be investigated, as they are present in 36% of such cases. 1 Additionally, decreased portal flow velocity below 15 cm/s in cirrhotic patients is a significant modifiable risk factor that warrants monitoring. 2