From the Guidelines
Antiphospholipid testing during pregnancy can be reliable but has important limitations, and the most recent guidance from the ISTH-SSC subcommittee on lupus anticoagulant/antiphospholipid antibodies 1 emphasizes the need for careful interpretation of test results.
Key Considerations
- Testing is most reliable when performed before pregnancy or at least 12 weeks after delivery, as pregnancy itself can cause transient positive results that don't represent true antiphospholipid syndrome (APS) 1.
- If testing is necessary during pregnancy, results should be interpreted cautiously and confirmed with repeat testing, considering the potential for false positives with certain medications or acute infections.
- The standard testing panel includes lupus anticoagulant, anticardiolipin antibodies (IgG and IgM), and anti-β2 glycoprotein I antibodies, with positive tests requiring confirmation on two occasions at least 12 weeks apart for a definitive APS diagnosis 1.
Clinical Recommendations
- Women with recurrent pregnancy loss, unexplained late pregnancy complications, or thrombotic events should be tested, ideally before conception or postpartum, to assess their risk and guide management decisions 1.
- If APS is diagnosed, treatment typically involves low-dose aspirin and sometimes prophylactic heparin during pregnancy to reduce complications like miscarriage, preeclampsia, and thrombosis, as recommended by the 2020 American College of Rheumatology guideline for the management of reproductive health in rheumatic and musculoskeletal diseases 1.
Important Limitations
- False positives can occur due to various factors, including pregnancy itself, certain medications (especially anticoagulants), and acute infections, highlighting the need for cautious interpretation of test results and consideration of clinical context 1.
- The distinction between detection and interpretation of antiphospholipid antibodies for classification versus routine clinical care is critical, with classification criteria aiming to enhance specificity and improve research quality, while clinical care focuses on optimizing diagnosis and patient management 1.
From the Research
Antiphospholipid Testing Reliability
- The reliability of antiphospholipid testing during pregnancy is a critical aspect of managing antiphospholipid syndrome (APS) [(2,3,4,5,6)].
- Antiphospholipid syndrome is characterized by thrombosis and/or pregnancy complications in the presence of persistent antiphospholipid antibodies (APLA) 4.
- Laboratory diagnosis of APLA depends upon the detection of a lupus anticoagulant, which prolongs phospholipid-dependent anticoagulation tests, and/or anticardiolipin (aCL) and anti-β2-glycoprotein-1 (β2GPI) antibodies 4.
Factors Affecting Reliability
- Several factors are thought to have roles in the pathogenesis of adverse obstetric events related to APS, including platelet and endothelial cell activation, complement activation, and ultimate activation of the thrombotic pathway 2.
- The use of low-dose aspirin and heparin has improved the pregnancy outcome in obstetric APS, but current management does not prevent all maternal, fetal, and neonatal complications of APS 6.
- Clotting tests such as the activated partial thromboplastin time (aPTT) vary greatly during pregnancy, and the aPTT is often not even prolonged when antithrombotic levels of heparin are achieved 3.
Treatment and Management
- Heparin, usually combined with low-dose aspirin, is used in patients at risk for thrombosis 5.
- Pregnancy in women with APS is associated with increased rates of preeclampsia, placental insufficiency, and preterm delivery, so that attentive clinical care is required for best outcomes 5.
- Recent studies indicate that women at low risk for thrombosis may be treated with low-dose aspirin 5.