Bleeding in the antiphospholipid syndrome.

Antiphospholipid syndrome (APS) is an autoimmune disease characterized clinically by the occurrence of venous or arterial thrombosis, and/or pregnancy morbidity. The detection of persistently elevated levels of antiphospholipid antibodies (aPL) is a requisite laboratory feature for the diagnosis of APS. The positivity for at least one aPL test: lupus anticoagulant and/or IgG/IgM anticardiolipin and/ or IgG/IgM anti-β2 glycoprotein I antibodies must be detected. Sometimes aPL coagulopathy may start with a hemorrhagic syndrome when a severe thrombocytopenia, or an acquired thrombocytopathy, or an acquired factor VIII inhibitor, or an acquired prothrombin deficiency is present. aPL-associated thrombocytopenia is usually moderate without clinical manifestations. Except in the occasional situations in which thrombocytopenia is associated with thrombotic microangiopathy, such as catastrophic APS, bleeding is uncommon in APS patients. When platelet counts are less than 30 × 109/L and there are symptoms of bleeding, the treatments used are the same for idiopathic thrombocytopenic purpura. In rare occasions a hemorrhagic diathesis due to the occurrence of non-neutralizing anti-prothrombin antibodies causing severe hypoprothrombinemia (HPT) can be observed. Levels of prothrombin in plasma are less than 10-20% in cases with HPT-related bleeding requiring transfusion and/or corticosteroid treatment. The APS mainly causes thrombosis, and pregnancy losses. However, other clinical manifestations are also associated with the presence of persistent autoimmune aPL. Bleeding is uncommon but can be the first clinical manifestation in patients having severe thrombocytopenia or prothrombin deficiency.