Adults
Antiphospholipid syndrome (APS)
Unexplained thrombosis or pregnancy morbidity with antiphospholipid antibodies that persist for at least 12 weeks.
What to look for
- Venous or arterial thrombosis, especially when young, unprovoked or at unusual sites
- Pregnancy morbidity: recurrent early loss, fetal death, or preterm delivery from preeclampsia or placental insufficiency
- Livedo, thrombocytopenia, heart valve thickening, microvascular kidney disease
- Lupus anticoagulant, anticardiolipin or anti-β2-glycoprotein I positive on two occasions at least 12 weeks apart
What to do
- Test lupus anticoagulant, anticardiolipin IgG/IgM and anti-β2-glycoprotein I IgG/IgM. Anticoagulants interfere with lupus anticoagulant testing, so note what the patient is taking.
- Repeat positive tests after at least 12 weeks.
- For confirmed thrombotic APS, warfarin is preferred. DOACs, rivaroxaban in particular, are not recommended for high-risk APS (triple-positive or arterial events).
- Pregnancy planning needs specialist input; LMWH and low-dose aspirin are typical.
About this urgency level
Early specialist assessment changes outcomes. Send the usual workup with the referral, but don't hold the referral while waiting for results.
Timeframes are typical targets. Local pathways, capacity and clinical judgment come first.