Autoimmune disorder characterised by arterial and venous thrombosis, adverse pregnancy outcomes (for mother and foetus), and raised levels of antiphospholipid antibodies
Aetiology
Genetic predisposition
More common in females
While it can occur as a primary condition, it often occurs secondary to SLE (or another rheumatic or autoimmune disorder)
Pathophysiology
Antiphospholipid antibodies react against proteins that bind to anionic phospholipids on plasma membranes
Clinical features
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 discolouration 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 embolisation 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
