What Is Anti-Phospholipid Syndrome?

Anti-Phospholipid Syndrome is otherwise known as APLS or Hughes Syndrome. Dr Iqbal Malik, Consultant Cardiologist and Medical Director of OneWelbeck Heart Health, takes a closer look.

What is APLS?

Anti-Phospholipid Syndrome is a disease that increase the risk of arterial and venous system clots, due to the presence of auto-antibodies against the bodies cell surface phospholipids, part of the human cell wall.

APLS can affect people of all ages, including children and babies. But most people are diagnosed with APS between 20 and 50 years of age, and it affects 3 to 5 times as many women as men.

The effects are:

  1. Increased risk of clots
  2. Complications in pregnancy (slow baby growth- fetal growth retardation), pre-eclapmsia (a condition, with blood pressure rise, and kidney issues in the mother, affecting placenta function also, recurrent miscarriages
  3. A link to other auto-immune diseases such as Lupus

How does APLS affect you?

APLS may present in a number of ways.


  • In the arteries, which may present as stroke, heart attack, or clots in other blood vessels. The arteries supply blood to your organs, and thus the organ is damaged by the clot. If you had an arterial clot first time, it is likely to come back in the arteries next time (>90%).
  • In the veins - they take blood away from the organ. People know about DVT (deep vein thrombosis) in the legs, but clots can occur in the blood pools in the brain (cerebral sinus thrombosis) AND travel to the lungs, Pulmonary Emboli (PE), which can also be fatal. If the clot was in the veins, it is likely to come back in the veins if it recurs (76%).
  • Micro-clots, which can affect kidneys, eyes, heart, and brain.


  • Loss of the baby
    • Lupus Anticoagulant (LA) Positive and  anticardiolipin antibody (ACA) are linked to death of the fetus, but  abeta2GPI (another antibody) is probably not when looking at fetal death >10 weeks
    • When looking at fetal death >20 weeks, all three antibodies appear linked (ACA and beta2GPI) , with the risk of still birth 3-5x higher.
    • Use of aspirin and blood thinners still carries about a 10% chance of fetal loss (not much lower than without treatment)
  • Pre-eclampsia leading to early delivery, and fetal growth retardation all increase.  LA seems worst for this.  About 10% of women with APLS develop severe pre-eclampsia and slowed baby growth needing urgent intervention. Conversely, about 11% of women needing such intervention for preeclampsia have APL antibodies, vs 1.4% of the control population.
  • Recurrent miscarriages:
    • Loss of the baby <10 weeks - the data on this is less clear.

You may get low platelets, skin rashes, and non-specific symptoms such as fatigue, pain, even memory issues:

  • Livedo reticularis is a skin condition caused by small blood clots that develop inside the blood vessels of the skin. Its can cause red or blue coloured blotches on white skin, and dark or brownish coloured blotches on black and brown skin. Some people also develop ulcers (sores) and nodules (bumps)
Livedo reticularis
Livedo reticularis

How is APLS diagnosed?

When diagnosing APLS, the clinical presentation is important, i.e. what happened to you. APLS might be diagnosed if you've had one or more blood clots plus:

  • 1 or more unexplained late miscarriage at or after week 10 of your pregnancy
  • 1 or more premature birth at or before week 34 of your pregnancy
  • 3 or more unexplained early miscarriages before week 10 of your pregnancy

Blood tests are also used. You may think that a positive blood test result means an undisputed APLS diagnosis, however it is a lot more complicated than that.

  • Lupus Anticoagulant (LA) Positive (this is 10x more risky than anticardiolipin antibody (ACA).
  • If you have LA and ACA and abeta2GPI (another antibody), you have the highest risk- a 44% chance of a clot in the next 10years- and the risk is reduced with blood thinners!
  • All three tests should be done, and then repeated at 12 weeks- “slightly positive” tests often go back to normal.
  • If pregnant, then the tests need to be repeated 3 months after the end of pregnancy, as they can be falsely positive in pregnancy.

How is APLS managed?

There are various avenues to take when it comes to managing APLS.

Risk factor reduction - the ones we know - blood pressure, weight, cholesterol etc. If you're diagnosed with APS, it's important to take all possible steps to reduce your risk of developing blood clots.

Effective ways of achieving this include:

  • quit smoking
  • eating a healthy, balanced diet – low in fat and sugar and containing plenty of fruit and vegetables
  • taking regular exercise
  • maintaining a healthy weight and losing weight if you're obese (have a body mass index of 30 or more)

Primary prevention - what happens if the antibody test is positive?

  • Aspirin- no strong support for this at 75mg or 300mg.
  • One study suggest a 1.8% annual event rate, another 5.3% when all there antibodies are positive.  Aspirin did not help.

Secondary prevention - what should you do if you have had a clinical event?

  • Warfarin with INR 2-3 vs INR 3-4? The evidence base is weak- bleeding risk goes up with INR 3-4, without definite benefit- it tends to be used when there is arterial clot.
  • Catastrophic APLS- this thankfully rare issue is treated with anticoagulation (warfarin or heparin), steroids, and plasmapheresis (washing the blood to get rid of the antibodies).

Pregnancy issues

  • There is a recommendation of 75mg-150mg after 12 weeks gestation, and definitely by 16-20 weeks to reduce pre-eclampsia. The evidence is weak.
  • Recurrent miscarriage in the past with APLS. The evidence is weak, but aspirin 75-150mg and low dose heparin tends to be given, in hope rather than conviction.
  • Patients with APLS without a history of clots getting to second and third terms of pregnancy are often given aspirin subcutaneous heparin.

Patent Foramen Ovale (PFO) - what should you do if you have both APLS and PFO?

  • 25% of the population have a PFO - if you have never had a clot, it is NOT a risk factor for clot and does NOT need to be closed.
  • If you have had a clot, consensus in the USA guidelines, which I agree with, is that a large shunt across your PFO means risk of clot travelling from veins to arteries and the PFO should probably be closed.


In short, if you have had blood clots, you need specialist care. It may be that you don't have APLS, and the antibody test may become negative again. If you do have APLS, you will need lifelong monitoring and really need to pay attention to your health.

For more information on APLS, visit the NHS website.