Anti-Phospholipid Syndrome

Autoimmune disorder that manifests clinically as recurrent venous or arterial thrombosis and/or fetal loss

Aetiology

  • Genetic predisposition
  • More common in females
  • Some patients with APS have no evidence of any definable associated disease (primary APS), while, in other patients, APS occurs in association with SLE or another rheumatic or autoimmune disorder (secondary APS)

Pathophysiology

  • Antiphospholipid antibodies react against proteins that bind to anionic phospholipids on plasma membranes

Clinical presentation

Venous

  • DVT/PE
  • Recurrent pulmonary emboli or thrombosis can lead to life-threatening pulmonary hypertension
  • Livedo reticularis - blood clots in capillaries lead to swelling of venules, resulting in a purplish, net-like discoloration of the skin

Arterial

  • May contribute to an increased frequency of stroke or MI, especially in younger individuals
    • Strokes may develop secondary to in situ thrombosis or embolization that originates from the valvular lesions of Libman-Sacks (sterile) endocarditis, which may be seen in patients with APS

Others

  • Catastrophic APS (rare) - multiorgan infarctions over a period of days to weeks, often fatal
  • Miscarriage
    • Late spontaneous fetal loss (second or third trimester) is common; however, it can occur at any time during pregnancy
    • Recurrent early fetal loss (< 10 weeks’ gestation) is also possible
  • Many patients have migraine

Investigations

Bloods

  • Thrombocytopenia
  • Prolongation of aPTT (partial thromboplastin time)
  • Lupus anticoagulant, anti-cardiolipin antibodies and anti-beta 2 glycoprotein may be positive

Management

  • Anticoagulation for those with an episode of thrombosis - acute LMWH then warfarin or aspirin prophylaxis
    • Patients who are found to have positive antibodies but who have never had had an episode of thrombosis do not require anti-coagulation
  • LMWH and aspirin used during pregnancy for patients with recurrent pregnancy loss