Antiphospholipid Syndrome-Diagnostic and Methodologic Approach

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by venous and arterial thrombosis and obstetric complications, driven by antiphospholipid antibodies (APLAs). This review synthesizes the latest advancements and current understanding, diagnosis, and treatment of APS. APLAs, including lupus anticoagulant (LAC), anticardiolipin (aCL), and anti-β2-glycoprotein I (aβ2-GPI), interfere with coagulation and endothelial function, as well as with placental health. APS can be primary or secondary; it is often associated with systemic autoimmune diseases like lupus. The pathogenesis of APS remains only partially understood. APLAs promote thrombosis through endothelial damage, platelet activation, and inflammatory signaling pathways. Laboratory diagnosis relies on persistent positivity for APLAs and LAC through tests like ELISA and clotting assays, following a three-step confirmation process. New integrated test systems have been introduced to improve standardization. Classification criteria have evolved, with the 2023 EULAR-ACR criteria providing a weighted, domain-based scoring system, enhancing diagnostic precision. Catastrophic APS (CAPS) is a severe, rare manifestation of APS, characterized by multi-organ failure due to rapid, widespread microthrombosis and systemic inflammation, which requires urgent anticoagulation. Seronegative APS is proposed for patients with clinical features of APS but negative standard antibody tests, possibly due to non-criteria antibodies or transient immunosuppression. Treatment primarily involves long-term anticoagulation with vitamin K antagonists; direct oral anticoagulants are generally not recommended. APS diagnosis and management remain complex due to clinical heterogeneity and laboratory challenges. Continued refinement of diagnostic tools and criteria is essential for improving outcomes in this life-threatening condition.