Transcription of 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)
2 Cardiolipin Antibody 2-GPI Antibody PTT-LA dRVVT Hexagonal phase confirmation dRVVT confirm dRVVT 1:1 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.
3 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. 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.
4 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.
