Mesenteric venous thrombosis

Definition and Incidence

• Thrombosis of a mesenteric vein
• Accounts for 5-15% of mesenteric ischaemia
• Associated with a 30-50% mortality and a high recurrence rate, esp. within 30 days

Classification

• Acute (sudden onset)
• Subacute (over days to weeks)
• Chronic (pain-free, extensive collateralisation)

Aetiology

• Any pro-thrombotic state
  • Hereditary Thrombophilia - 75%
    • Anti-Thrombin III deficiency
    • Protein C deficiency or Protein S deficiency
    • Factor V Leiden mutation
    • Prothrombin G20210A
  • Acquired
    • Paroxysmal Benign Haemoglobinuria
    • Myeloproliferative states
  • Intra-abdominal
    • IBD
    • Pancreatitis
    • Peritonitis/sepsis
    • Diverticulitis
    • Post-op (esp. Splenectomy)
    • Portal HTN/Portal Vein Thrombosis
    • Malignancy
  • Pregnancy
  • OCP in young women (4-5%)

Pathology

• Primary or secondary (aetiology found)
• Intra-abdominal compression
  • Large vessel thrombosis with progression to small vessels
• Hypercoagulable state
  • Small vessel thrombosis with progression to large vessels
• Strangulated segment e.g. closed loop obstruction
• Compared to arterial ischaemia:
  • Insidious onset and progression of ischaemia
  • Gradual transition to unaffected bowel

Presentation

• Acute/subacute:
  • Depends on extent of thrombus, size of vessel and depth of ischaemia
  • Mucosal ischaemia: abdo pain, diarrhoea
  • Transmural: GIT bleeding, peritonitis, perforation
  • Abdominal pain not explained by abdominal findings
• Chronic:
  • MC in setting of portal hypertension
  • Management is to prevent variceal bleeding

Investigations

• Lactate/metabolic acidosis late sign
• AXR abnormal in 50-75%
  • But ischaemic signs only in 5%
  • Thumb-printing
  • Pneumatosis
  • Portal gas
• CT: 90% sensitivity, visible as a venous filling defect
  • May miss small vessel thromboses
• Mesenteric angiography may then have a role

Management

• Medical in the absence of infarction
  • Anticoagulation
    • Improves survival and decreases recurrence
• At diagnosis/intra-operative
  • IV heparin 5000 unit bolus, then APTT twice upper limit of normal
  • Warfarin when stable
• NGT
• IV fluids / antibiotics
• NBM
• Surgery: for peritonitis
  • Conserve bowel length
  • Consider relook laparotomy
• Prothrombotic screen