Haematology 

 

What is warfarin?

Warfarin is a type of medicine known as an anticoagulant, or blood thinner. It makes your blood flow through your veins more easily. This means your blood will be less likely to make a dangerous blood clot. Warfarin is used to treat people who have had a previous blood clot, such as DVT or PE.

It's also used to prevent blood clots if you're at high risk of having them in the future. This often includes people who have an abnormal heartbeat (atrial fibrillation), a replacement or mechanical heart valve, a blood clotting disorder (also known as thrombophilia) or after an operation.

Warfarin is only available on prescription. It comes as tablets or as a liquid that you swallow.

Can I continue to take warfarin throughout pregnancy?

Warfarin is usually avoided in pregnancy because of the risk of complications for the baby. Women who are on Warfarin should be counselled about the risk before pregnancy occurs. If a pregnancy is still desired, LMWH should be substituted for Warfarin as soon as the pregnancy test is positive (less than six weeks of pregnancy). Warfarin can be given to women who need anti-coagulation in the post-partum period, as an alternative to LMWH as it is also safe in breastfeeding.

What will I be given instead of warfarin?

Once you have a positive pregnancy test you should let your anticoagulant clinic know immediately. They will arrange a review for you and a switch over to Low Molecular Weight Heparin (LMWH).

LMWH is in the form of an injection and you are likely to be prescribed one injection to be taken every 12 hours.

These injections are also anticoagulants so will treat or prevent any blood clots.

Are there any risks linked with LMWH treatment?

LMWH is considered to be safe to use in pregnancy as it does not cross the placenta and does not affect the baby.

The most common side effect for the mother is a small amount of bruising at the injection site. The risk of bleeding with low dose LMWH, due to the “thinning” of the blood, is small. LMWH doesn’t usually cause bleeding by itself, but bleeding caused by other things, for example from a threatened miscarriage, may be a little heavier than normal.

Women are usually advised to stop taking their LMWH injections when they start in labour, or leave out the dose on the morning of a planned delivery.

An epidural or spinal anaesthetic cannot be given within 24 hours of a dose of LMWH. Your injections will usually be started again at least four to six hours after delivery.

Around 5% of women experience a skin rash at the site of the injection. If this happens, or if there is any unexplained bruising or bleeding, please contact the hospital the number on the back of this leaflet.

If you have an allergy to your injection we will change to a different brand, there are lots to choose from.

How do you give LMWH?

The syringes come ready prepared with the correct dose for you to give. You will be shown how to give your own injections, and most women, or their partners, manage this very easily. The needle on the syringe is very fine, and although the injection may sting slightly, it is not usually too painful. You will be given a sharps box (a strong plastic box just for syringes) so that you can dispose of the syringes safely.

Instructions

  • Make sure you have a sharps box and cotton wool ball ready for after the injection.
  • Wash your hands before giving the injection.
  • Sit in a comfortable position so that you are relaxed.
  • Select the site for injection.

Suitable injection sites include the sides of your tummy (avoiding the area near your belly button) and the front of your thighs. Avoid bruised, scarred, reddened or hard areas.

Rotate the sites to avoid skin irritation. LMWH injections in your arms should be avoided as it is more painful and less effective.

  • Take the syringe and with your thumb and forefinger carefully remove the plastic sheath covering the needle. Take care not to touch the sterile needle.
  • Do not remove the air bubble in the pre-filled syringe. Hold the syringe halfway down the barrel in one hand.
  • Use your other hand to gently grasp a fold of skin for your injection. Hold the skin between your thumb and index finger.
  • Hold the syringe at a right angle to the skin, like a dart. Quickly insert the needle all the way into the skin fold.
  • Push the syringe plunger down steadily.
  • Keep pushing until all of the fluid is injected into the skin.
  • Make sure you hold the skin fold throughout the injection.
  • Release the skin fold and pull the needle straight out at the same angle that it was inserted.
  • Place cotton wool over the injection site and apply constant pressure for two to three minutes.
  • You may find that the area stings afterwards - this is normal.
  • To avoid bruising do not rub the injection site after you have injected yourself.
  • Discard the needle in the sharps container and store out of reach of children.
  • When the container is full to the line, close and lock it and give to your GP, nurse, midwife or the hospital for disposal.
  • Do not put it in the household rubbish.
  • If you forget to take a dose and are close to your next scheduled dose, skip the missed dose and inject the next dose at the regularly scheduled time. Do not take a double dose.
  • You should ask your family doctor (GP) to prescribe any further supplies of Fragmin. (If your GP is unwilling to do this, please let us know).
  • Your chemist will need at least 24 hours to order the Fragmin for you. Please order in plenty of time to avoid running out.
  • To regulate the dose of your LMWH, we may need to do a blood test. The blood test must be done no earlier than two and a half hours after you have injected yourself but no later than four hours after the injection.

How should LMWH be stored?

It does not need to be kept refrigerated. Store the syringes at room temperature (between 15 and 30ºC). It is important to keep the stock of injections and sharps box in a safe place, out of reach of children. You should ask for a new sharps box before the old one is completely full. Used sharps boxes should be closed and locked and returned to your GP, nurse, midwife or the hospital for disposal. Do not put it in the household rubbish.

Important

Tell a nurse or doctor if you notice any of the following side effects:

  • Red spots under the skin which does not go away when you put pressure on them.
  • You bruise more easily than usual.
  • Your injection sites become red and itchy.

Medication

Do not take any drugs other than those prescribed by your doctor while you are taking your LMWH injections.

If you need to consult with another doctor or see your dentist, be sure to tell them that you are being treated with LMWH.

Monitoring of Medication throughout Pregnancy

During your pregnancy you will be monitored by the specialist haematology obstetric nurse, rather than your regular warfarin clinic.

LMWH is monitored by a venous blood test called AntiXa level. This is normally taken three to four hours after your morning dose of medication. Depending on this result the specialist nurse will adjust your dosing of injections accordingly.

 

Feedback

Your feedback is important to us and helps us influence care in the future.

Following your discharge from hospital or attendance at your outpatient appointment you will receive a text asking if you would recommend our service to others. Please take the time to text back, you will not be charged for the text and can opt out at any point. Your co-operation is greatly appreciated.

Further information

For further information please contact below

Haematology Liverpool

Contact Details: 0151 706 3397

Text phone number:  18001 0151 706 3397

 

Author: Haematology Liverpool

Review date: April 2029

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