Antiphospholipid syndrome

1. Big picture

Antiphospholipid syndrome (APS) is an autoimmune acquired thrombophilia. The key paradox is:

In vitro: prolonged activated partial thromboplastin time (aPTT). In vivo: thrombosis, not bleeding.

The examiner usually wants you to recognize:

1. Venous thrombosis: deep vein thrombosis (DVT), pulmonary embolism (PE).
2. Arterial thrombosis: stroke, transient ischemic attack (TIA), myocardial infarction in young patients.
3. Pregnancy morbidity: recurrent miscarriage, fetal death, severe preeclampsia, placental insufficiency.
4. Laboratory confirmation: persistent antiphospholipid antibodies on repeat testing ≥12 weeks apart.
5. Treatment: long-term anticoagulation, usually warfarin/coumarin, not direct oral anticoagulants (DOACs), especially in high-risk APS.

The attached hematology textbook describes APS as an autoimmune disease characterized by venous or arterial thrombosis and recurrent miscarriage due to antiphospholipid antibodies.

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