APS is diagnosed when medical, obstetric, and appropriate laboratory findings are present. Diagnosis of APS requires the presence of at least 1 of the clinical criteria and at least 1 of the laboratory criteria:
Clinical criteria
Vascular thrombosis
Pregnancy morbidity
3 or more unexplained consecutive miscarriages with anatomic, genetic, and hormonal causes excluded
1 or more unexplained death(s) of a morphologically normal fetus at or after the 10 weeks’ gestation
1 or more premature birth(s) of a morphologically normal neonate at or before 34 weeks’ gestation, associated with severe preeclampsia or severe placental insufficiency
Laboratory criteria
aCL: Immunoglobulin G (IgG) and/or immunoglobulin M (IgM) isotype is present in medium or high titer on 2 or more occasions, 6 or more weeks apart.
Demonstration of a prolonged phospholipid-dependent coagulation on screening tests (eg, activated partial thromboplastin time, kaolin clotting time, dilute Russell viper venom time, dilute prothrombin time, Textarin time)
Failure to correct the prolonged screening test result by mixing with normal platelet-poor plasma
Shortening or correction of the prolonged screening test result with the addition of excess phospholipids
Exclusion of other coagulopathies as clinically indicated (eg, factor VIII inhibitor) and heparin