Antiphospholipid Syndrome (APS) Diagnostic Algorithm

1 Figure. Antiphospholipid Syndrome (APS) Diagnostic Algorithm1,11-13 Vascular Thrombosis and/or Pregnancy Morbidity Clinical Criteria Laboratory Criteria Pregnancy morbidity defined as at least 1 of the following: 1) 1 unexplained deaths of morphologically normal fetus 10 weeks gestation 2) 1 premature births of morphologically normal fetus <34 weeks gestation, because of eclampsia, pre-eclampsia, or placental insufficiency 3) 3 consecutive spontaneous abortions before 10th week of gestation Cardiolipin antibody negative 2-GPI antibody negative APS identified Cardiolipin antibody positive 2-GPI antibody positive IgG and/or IgM >40 GPL/MPL on 2 tests, 12 wks apart IgG and/or IgM >99th percentile of controls on 2 tests, 12 wks apart IgG and/or IgM 40 GPL/MPL on 2 tests, 12 wks apart IgG and/or IgM 99th percentile of controls on 2 tests, 12 wks apart Abnormal LA positive LA negative Correction No correction Both PTT-LA and dRVVT normal LA negative LA negative LA negative Negative Positive Negative Positive Abnormal Lupus anticoagulant (LA) test (both PTT-LA and dRVVT) Cardiolipin Antibody 2-GPI Antibody PTT-LA dRVVT Hexagonal phase confirmation dRVVT confirm dRVVT 1.

2 1 Mixing Study Repeat LA testing and confirmation after 12 wks APS-associated clinical features such as thrombocytopenia, livedo reticularis, and stroke are excluded from the 2006 international consensus classification criteria to maintain Diagnostic Only one positive test (PTT-LA or dRVVT) is required for LA The presence of LA is confirmed when the PTT-LA is abnormal and neutralization by hexagonal phase phospholipids is The hexagonal phase confirm test also incorporates a heparin neutralizer and a source of normal plasma (for patients on anticoagulant therapy such as warfarin), which further improves the specificity for LA. At Quest diagnostics , a positive dRVVT screen reflexes to dRVVT confirm (phospholipid neutralization) which reflexes to a dRVVT mixing study. Repeat testing recommended in the figure is in accordance with the classification criteria in the 2006 international consensus Positive cardiolipin IgG or 2-GPI IgG tests are associated with a high risk of APS, while positive cardiolipin IgM or 2-GPI IgM tests are associated with a low APS ,7 Cardiolipin or 2-GPI IgM antibodies very rarely occur without IgG antibodies in APS ,7 If LA, cardiolipin, and 2-GPI antibodies are all negative, APS is Non first-line Antiphospholipid antibodies may help identify risk of developing clinical symptoms in symptomatic patients with negative test results.

3 See text. PTT-LA indicates the activated partial thromboplastin time assay that is sensitive for lupus anticoagulant antibodies; and dRVVT, dilute Russell s viper venom time assay. References This figure was developed by Quest diagnostics based on references 1,11,12, and 13. It is provided for informational purposes only and is not intended as medical advice. A physician s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient. LA negative Content reviewed 02/2013 Quest, Quest diagnostics , any associated logos, and all associated Quest diagnostics registered or unregistered trademarks are the property of Quest diagnostics . All third party marks - and - are the property of their respective owners. 2013 Quest diagnostics Incorporated. All rights reserved.

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