What is Venous Thrombosis?

• Thrombosis is a blood clot in a blood vessel either a vein or an artery.
• Venous thrombosis occurs in a vein. Veins are the blood vessels that take blood towards the heart and lungs.
• A deep vein thrombosis (DVT) is a blood clot that forms in a deep vein of the leg, calf or pelvis.

Why should this information concern you?

• This information is important for you to consider if you are thinking of having a baby, you are already pregnant or you have just had a baby.
• Your physician will assess you during the start of your pregnancy and again following the birth of your baby for your risk of developing a DVT.

Who is at risk of venous thromboembolism?

• The risk for venous thrombosis for pregnant women is 1 in 500, which is ten times more likely than for women who are the same age but not pregnant.
• You are at the highest risk of getting a DVT just after you have had your baby. However, it can occur at any time during your pregnancy including the first three months.
• You are over 35 years of age.
• You are overweight with a body mass index greater than 30.
• You are a smoker.

Your risk of developing venous thromboembolism increases if the following apply to you

Prior pregnancy/medical conditions including –

• You have already had three or more babies.
• You have had a previous venous thrombosis.
• You have a mother, father, brother or sister who have had venous thrombosis.
• You have a thrombophilia condition which makes a blood clot more likely.
• You have a medical condition such as certain kinds of heart disease, lung disease or arthritis.
• You have severe varicose veins.
• You are a wheelchair user.

Pregnancy-related conditions –

• You are pregnant with more than one baby.
• You have become dehydrated.
• You are unwell following fertility treatment (ovarian hyperstimulation syndrome).
• You are less mobile than normal in your pregnancy due to the following:
  • Vomiting in early pregnancy.
  • You are being treated in a hospital with a severe infection such as appendicitis or a kidney infection.
  • You have had an operation.
  • You have been travelling for four hours or longer (by air, car or train).
  • You have been admitted to a hospital.

After the birth of your baby –

• You have experienced prolonged labour (more than 24 hours) or have had a caesarean birth.
• You have lost a lot of blood after you have had your baby.
• You needed to receive a blood transfusion following the birth of your baby.

Why is a DVT serious?

• Venous thrombosis can be serious because the blood clot may separate and travel in the bloodstream until it gets stuck in another part of the body, such as in the lung (known as pulmonary embolism or PE). This is potentially life-threatening.
• Diagnosing and treating a DVT reduces the risk of developing a pulmonary embolism.

What are the symptoms of a DVT?

• A red and hot swollen leg.
• Swelling in your entire leg or just part of it.
• Pain and/or tenderness – you may only experience this when standing or walking or your leg may just feel heavy.

What are the symptoms of a pulmonary embolism?

• You may experience sudden unexplained difficulty in breathing.
• You may feel tightness in your chest or chest pain.
• You may feel very unwell.

Seek help immediately if you experience any of these symptoms.

How can I reduce my risk of getting a DVT or PE?

There are steps you can take to reduce your risk of getting a DVT or PE –

• Staying as active as you can.
• Wearing special stockings (graduated elastic compression stockings) to help prevent blood clots from forming.
• Keeping hydrated by drinking normal amounts of fluids.
• Stopping smoking.
• Losing weight before pregnancy if you are overweight.

You may be advised to start medication treatment with injections of heparin (an anticoagulant) to ‘thin the blood’. The common type of heparin used is called ‘Clexane’.

What does Heparin treatment involve?

• Heparin is given as an injection under the skin at the same time every day (sometimes twice daily).
• The dose is worked out for you depending on your risk factors and your weight in early pregnancy or before you became pregnant.
• You (or a family member) will be shown how and where in your body to give the injections.
• You will be provided with the needles and syringes (already made up) and will be given advice on how to store and dispose of these.

How should you administer Heparin?

• First, wash your hands with soap and water.
• Sit or lie in a comfortable position so that you can see the part of your stomach where you are going to inject.
• Choose an area on either the left or the right side of your stomach at least two inches away from your navel – out towards your side.
• Carefully remove the protective cap from the end of the syringe taking care not to bend the needle.
• Hold the syringe like a pencil in the hand you normally write with. Pinch a fold of the skin you are going to inject between the thumb and index finger of your other hand.
• Insert the whole length of the needle into the fold of skin, keeping hold of the skin between your thumb and forefinger. Make sure you keep the needle straight and at right angles to your body.
• Press down gently but firmly on the plunger until it stops and the syringe is empty.
• Your injection is now finished and you can now gently remove the needle, taking care to keep it straight.

Are there any risks to me or my baby from taking Heparin?

• Heparin does not cross the placenta and therefore cannot harm your baby.
• There may be some bruising where you inject – this will usually fade in a few days.
• One or two women in every 100 (1% to 2%) will have an allergic reaction. If you notice a rash after injecting, you should inform your doctor so that the type of heparin can be changed.

What should I do when my labour starts?

• If you think you are going into labour, do not have any more injections.
• If the plan is to induce your labour, you should stop your injections 12 hours (24 hours if you are on a high dose) before the planned date. Your physician will review this with you.

What if I have a caesarean birth?

• If you are having a planned caesarean section, your last injection should be 12 hours (24 hours if you are on a high dose) before the planned caesarean delivery.
• Your injections will usually be re-started within six hours of the operation.

What happens after my baby is born?

• It is important to be as mobile as possible after you have had your baby and avoid becoming dehydrated.
• If you were on heparin before the baby’s birth, you may need to continue this for between 1 and 6 weeks afterwards.
• Even if you weren’t having injections in pregnancy, you may need to start having injections for the first time after birth.

Is it safe to breastfeed my babies if I am on Heparin treatment?

• Yes, it is safe for you to breastfeed your baby while you are being medicated with heparin.
• Your physician may need to change your medication type once your baby is born. The alternative medication is called Warfarin. This is also safe to use when breastfeeding your baby.

Reference acknowledgement –

• RCOG Patient Information Leaflet on Reducing the Risk of Thrombosis and Embolism during Pregnancy and the Puerperium (November 2009).
• A patient guide to home use clexane-patient information by Stockport, National health service, UK. (August 2012).