Pathogenesis and clinical aspects: Antiphospholipid syndrome (APS) is characterized by recurrent arterial or venous thromboembolism or pregnancy loss in association with antibodies directed against anionic phospholipids or against plasma proteins bound to anionic phospholipids. It occurs in 15-30 % of patients suffering from systemic lupus erythematosus (secondary APS) but can also occur without an underlying connective tissue disease (primary APS). The reason for the huge variety of clinical manifestations is thromboembolic vaso-occlusive disease and not vasculitis in blood vessels of different sizes and sites (e.g. deep vein thrombosis, pulmonary embolism and cerebrovascular disease). Accordingly, fetal abortion is also caused by infarctions of blood vessels in the placenta typically after the tenth week of gestation.
Diagnostics: Establishing the correct diagnosis of APS is not easy. Diagnosis should not rely on only slightly or temporarily elevated levels of AP antibodies as thrombosis might occur due to other reasons even in patients with AP antibodies. The estimation of the risk of thrombotic complications as well as the type and intensity of a suitable anticoagulation prophylaxis are challenging in the treatment of patients with APS.
Therapy: Antiplatelet agents (aspirin), heparin and vitamin K antagonists are used for therapy. Immunosuppression is not effective for the prevention of thromboembolic complications; therefore, not only problem issues on laboratory diagnostics but also current therapeutic recommendations are presented.