Antiphospholipid syndrome Investigation Indications for screening BSH Q Does the patient have a history of ischemic stroke at a young age (< 50 years)? Q Does the patient have a history of recurrent unprovoked proximal DVT or PE after cessation of anticoagulation? Q Does the patient have a history of recurrent pregnancy loss ( 3 pregnancy losses) prior to 10 weeks gestation? Yes to any Screen women with 3 pregnancy losses before 10 weeks gestation for antiphospholipid antibodies. B Screen young adults (< 50 years) with ischemic stroke for antiphospholipid antibodies. B Test for antiphospholipid antibodies in patients with unprovoked proximal DVT or PE after stopping anticoagulation (for 7 days), as the presence of antiphospholipid antibodies will influence the balance of risks and benefits and support long-term anticoagulant therapy. B Avoid routine screening for antiphospholipid antibodies in unselected patients with ischemic stroke. D No to all Initial laboratory testing Obtain lupus anticoagulant testing and testing for IgG antibodies to -2-glycoprotein I (either IgG anticardiolipin ELISA or an IgG anti- -2-glycoprotein I ELISA). An anticardiolipin ELISA may detect antibodies to other phospholipid binding proteins as well as anti- -2-glycoprotein I. B Confirmatory testing Q Is lupus anticoagulant testing positive? Yes Perform a confirmatory test (e.g., using a high phospholipid concentration, platelet neutralizing reagent or a lupus-anticoagulant insensitive reagent) to definitively establish the presence of lupus anticoagulant. A No Classification Diagnose antiphospholipid antibody syndrome in patients meeting laboratory criteria on two or more occasions at least 12 weeks apart, in addition to either thrombotic criteria or obstetrical criteria. Classification criteria for antiphospholipid syndrome (Sydney criteria) Laboratory criteria (present on 2 occasions at least 12 weeks apart) Positive lupus anticoagulant Elevated anticardiolipin antibodies Elevated anti- 2 glycoprotein antibodies Thrombotic criteria Arterial thrombosis Venous thrombosis Small vessel thrombosis Obstetrical criteria 3 unexplained miscarriages at < 10 weeks gestation 1 unexplained fetal death > 10 weeks gestation 1 pre-term birth before 34th week gestation due to preeclampsia or placental insufficiency Diagnostic criteria are not met