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
Antibodies lead to a conformational change in β2 glycoprotein 1 (a protein with unknown function in health) which leads to activation of both primary and secondary haemostasis and vessel wall abnormalities
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
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