Antiphospholipid syndrome
An autoimmune tendency to form blood clots, with important effects on pregnancy. Very manageable once recognised.
What is antiphospholipid syndrome?
Antiphospholipid syndrome (APS) is an autoimmune condition in which antibodies make the blood more likely to clot. It can cause clots in the veins or arteries and complications in pregnancy. It can occur on its own or alongside lupus.
What it can cause
- Clots in the legs (DVT) or lungs (pulmonary embolism)
- Stroke or mini-stroke at a young age, heart attack
- Recurrent early miscarriages, a later pregnancy loss, severe pre-eclampsia or a poorly growing baby
- A lace-like purple rash on the legs (livedo), low platelets, heart valve changes
How it is diagnosed
Diagnosis needs both a clinical event (a clot or a pregnancy complication) and persistently positive antibodies:
- Lupus anticoagulant
- Anticardiolipin antibodies
- Anti-β2-glycoprotein I antibodies
Antibodies must be positive on two occasions at least 12 weeks apart, because brief positives occur with infections. Testing for lupus anticoagulant is affected by blood thinners, so timing matters.
How it is treated
- After a clot: long-term warfarin (target INR usually 2–3), managed with regular INR checks
- The newer blood thinners (DOACs such as rivaroxaban) are not recommended in high-risk APS, especially with arterial clots or "triple-positive" antibodies
- In pregnancy: low-dose aspirin and heparin injections greatly improve the chance of a healthy baby — warfarin is switched before 6 weeks of pregnancy
- Hydroxychloroquine if there is lupus
- Stop smoking; avoid oestrogen-containing contraceptive pills
In line with the 2019 EULAR recommendations for antiphospholipid syndrome in adults.
Common questions
Can I have a healthy pregnancy with APS?+
Why can't I take the newer blood thinners?+
Is a single positive antibody test enough to diagnose APS?+
Clots or pregnancy losses unexplained?
Testing and a clear plan make a real difference. Walk-in, no appointment needed.
Clinic timings & location