In the UK, the diagnosis of antiphospholipid syndrome is met if one clinical criteria and one laboratory criteria is met.
Clinical Criteria:
Vascular thrombosis – 1 or more clinical episode(s) of arterial, venous or small-vessel thrombosis.
Pregnancy morbidity – 3 or more unexplained consecutive spontaneous abortions before 10 weeks gestation OR 1 or more premature birth(s) of a normal neonate before the 34 weeks gestation because of eclampsia or severe pre-eclampsia OR 1 or more unexplained deaths of morphologically normal fetuses at or beyond the 10th week of gestation.
Laboratory Criteria
Lupus anticoagulant – present in the plasma on 2 or more occasions, at least 12 weeks apart.
Anticardiolipin antibody – present in medium or high titre (>40 IgG GPL units or IgM phospholipid [MPL] units, or >99th percentile) on 2 or more occasions, at least 12 weeks apart.
Anti-beta2-glycoprotein I – present in serum or plasma (in titre >90th percentile) on 2 or more occasions, at least 12 weeks apart.