see also:

• thrombosis with thrombocytopenia syndrome (TTS / VITT / VIPIT)

• an uncommon site for venous thrombosis
• two thirds of SVT patients are men

• transient risk factors
  • thrombosis with thrombocytopenia syndrome (TTS / VITT / VIPIT) eg. post-AZ Covid-19 vaccination
  • intra-abdominal infections
  • abdominal surgery
  • hormonal therapy
  • pregnancy
  • puerperium
• persistent acquired factors
  • cirrhosis
  • solid cancers
  • myeloproliferative neoplasms
  • inflammatory bowel disease (IBD)
  • antiphospholipid syndrome
  • other haem diseases such as polycythaemia rubra vera, paroxysmal nocturnal haemoglobinuria
  • autoimmune diseases such as behcet's disease
• inherited thrombophilia factors
  • Factor V Leiden mutation
  • Prothrombin G20210A mutation
  • JAK2V617F mutation
  • Protein C deficiency
  • Protein S deficiency
  • Antithrombin deficiency

• generally non-specific symptoms (nausea, vomiting, anorexia, diarrhoea or constipation, and fever) although abdominal pain occurs in over half and less commonly GIT bleeding and/or ascites may occur
• portal vein thrombosis (PVT)
  • acute presentation:
    • abdominal pain
  • chronic:
    • portal hypertension features such as hypersplenism, ascites, oesophageal varices, and the presence of portal cavernoma or other porto-systemic collateral veins on imaging
• mesenteric vein thrombosis (MVT)
  • acute presentation:
    • sudden onset of abdominal pain and particularly if it extends into the superior mesenteric vein, may be complicated by intestinal infarction in one third of patients which may be fatal
  • subacute presentation:
    • abdominal pain lasting for several days without intestinal infarction
  • chronic presentation:
    • signs of portal hypertension
• splenic vein thrombosis
  • up to 17% are asymptomatic
  • almost 2/3rds have abdominal pain
  • almost 1/3rd have gastrointestinal bleeding (29%)
  • around 23% have nausea
• Budd-Chiari syndrome (BCS)
  • least common manifestation of SVT, with reported incidence rates of around 1–2 cases per million inhabitants per year (5-7 per million in the Eastern countries)
  • includes any obstruction of the hepatic venous outflow located between the small hepatic venules and the confluence of the IVC into the right atrium

• D-Dimer is generally elevated but has limited utility if there are other conditions present which may cause this such as cirrhosis, post-surgery, neoplasia or infections
• Doppler USS is generally first line for suspected portal V thrombosis as has high sens and spec.
• CT abdopelvis with contrast is the standard 1st line investigation for other types and for PVT when USS is not available

• if incidental and asymptomatic, current recommendation is no Rx unless acute extensive SVT or ongoing chemotherapy in cancer patients
• for other patients:
  • early anticoagulation if benefits outweigh risks
  • see Vasc Health Risk Manag. 2019; 15: 449–461. Splanchnic Vein Thrombosis: Current Perspectives