Antiphospholipid syndrome

Blood clotting (thrombosis) can occur:

• in the veins, causing pain and swelling, typically in the calf ( deep vein thrombosis or DVT) – this can sometimes lead to  pulmonary embolism if a piece of the clot breaks away and travels to the lung
• in the arteries, causing high blood-pressure or strokes
• in the brain, which can cause memory loss, migraines, forgetfulness, slurred speech, fits or visual disturbances.

In pregnancy, antiphospholipid syndrome can cause recurrent miscarriage. This is because the increased 'stickiness' of the blood means it is unable to pass through the smallest blood vessels in the afterbirth (placenta). This can happen at any time during the pregnancy but is most common between three and six months. APS can also cause other pregnancy complications such as high blood pressure (pre-eclampsia), small babies and early deliveries.

Other problems sometimes associated with antiphospholipid syndrome include:

• Heart problems – The heart valves may thicken and fail to work, or the arteries may thicken, leading to angina.
• Kidney problems – APS can cause narrowing of the blood vessels, resulting in high blood pressure.
• Infertility – Testing for antiphospholipid antibodies is becoming routine in infertility clinics.
• Skin problems – Some people develop a blotchy rash, often seen on the knees or wrists, with a lacy pattern (livedo reticularis).
• A low platelet count – A reduction in one of the white blood cells (platelets) is also found in some people with APS . Often there aren't any symptoms of this, although people with very low counts may bruise easily or experience abnormal or excessive bleeding.

Although these tests measure broadly the same thing, around 20 per cent of people with antiphospholipid syndrome will have a negative result in one test or the other, so one test alone could miss the diagnosis. Similarly, a single positive test may not be significant, especially if it's only just positive.

The tests are usually repeated after 6–8 weeks as levels of antiphospholipid antibodies vary and can sometimes be associated with infections or use of antibiotics.

Higher levels of antibodies suggest you may be at greater risk of blood clots and other symptoms, but even if you do test positive it doesn't mean that you will definitely have any of the problems described.

A past medical history (e.g. migraine, recurrent miscarriages) sometimes helps to make the diagnosis of APS.

• If you have antiphospholipid antibodies but no history of clotting, your doctor will probably recommend low-dose aspirin (75–100 mg) daily. This is not guaranteed to prevent blood clots, but is known to make the blood less 'sticky'. Research is currently comparing the use of aspirin with very low-dose warfarin.
• If you have APS and a history of clotting you're likely to be given warfarin to prevent further blood clots. Warfarin is taken by mouth. You will have regular blood tests to check what effect it is having – if necessary the dose will be adjusted.
• If you've had a number of miscarriages, but no history of clotting, the usual treatment is low-dose aspirin. However, injections of heparin are increasingly common, especially if the previous miscarriages happened in mid- to late pregnancy, or if there have been other pregnancy complications such as pre-eclampsia.
•  If you are on warfarin and you become pregnant you'll probably be changed over to heparin. This is because warfarin is potentially toxic to the baby.

Even with treatment, complications can sometimes occur towards the end of pregnancy. However, advances in the understanding and treatment of APS have resulted in many more successful pregnancies in women with APS.

With close monitoring of the pregnancy, there is now a very good chance that your baby will do very well with no long-term problems.