For a diagnosis of APS to be made, at least one clinical and one laboratory criteria must be met.
Clinical criteria:
- Vascular thrombosis: defined as one or more clinical episodes of arterial, venous, or small-vessel thrombosis in any tissue or organ confirmed by findings from imaging studies, Doppler studies, or histopathology.
- Pregnancy morbidity is defined as the following:
- One or more late-term (>10 weeks gestation) spontaneous abortions
- One or more premature births of a morphologically healthy neonate at or before 34 weeks gestation because of severe preeclampsia or eclampsia or severe placental insufficiency
- Three or more unexplained, consecutive, spontaneous abortions before 10 weeks gestation
Laboratory criteria:
- Lupus anticoagulant (LA): presents on two occasions at least 12 weeks apart with prolongation of at least one phospholipid-dependent coagulation test.
- Anti-cardiolipin antibodies (ACA): IgG/IgM ACA antibodies detected in medium to high titer on at least two occasions at least 12 weeks apart, measured by ELISA testing.
- Anti-ß2 GPI: IgG/IgM anti-ß2 GPI detected on at least two occasions at least 12 weeks apart, measured by ELISA testing.
