Antiphospholipid antibody (APLA) syndrome (APS) is a heterogeneous disorder defined by the finding of persistent APLA in patients with arterial or venous thrombosis or pregnancy morbidity. APS manifestations range from deep vein thrombosis to stroke and even rapid multiorgan failure (the rare catastrophic APS). APS may be primary or secondary; in both cases, however, the clinical consequences appear to be the same. Although crucial to thrombotic risk assessment and clinical management, current laboratory testing for APLA lacks standardization and data from randomized trials. Consequently, correlating laboratory findings with clinical features is still a challenge for clinicians facing APS. This chapter presents the current definition of APS and discusses its etiopathogenesis and diagnosis and approaches for its treatment.
