Clinical aspects of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disorder, characterized by thrombosis, either arterial or venous, and/or pregnancy morbidity in the setting of persistently positive antiphospholipid antibodies. These antibodies include the lupus anticoagulant, anticardiolipin, and anti-β₂-glycoprotein I. This syndrome was described in the early 1980s in patients with systemic lupus erythematosus (SLE) in whom clotting times had long been known to be abnormal. Since then, it has been recognized that APS can occur both with and without an accompanying systemic autoimmune disorder. Obstetric APS describes recurrent pregnancy loss and pregnancy morbidity associated with antiphospholipid antibodies. Catastrophic APS (CAPS) is the term used to describe the rare phenomenon of life-threatening, multiorgan thromboses associated with antiphospholipid antibodies. This chapter outlines the diagnosis and management of this complex condition.