How are blood tests done on children with IBD?

Blood tests are used to help diagnose and monitor your inflammatory bowel disease. Find out what to expect when you have a blood test.


When you have inflammatory bowel disease, it is likely that you will need quite a few blood tests, especially during your diagnosis, when you start treatments and if you have a flare. It is normal to feel a little worried about this, and sometimes it can be useful to learn about what will happen during a blood test.  

Usually you will have a blood test at every IBD clinic appointment, and sometimes more often. You may be able to have blood tests taken at your GP surgery, which is often easier if you live a long way from your hospital.

What happens when I have a blood test? 

Before your blood test, you should try to drink plenty of water and to keep warm. This will make it easier for the nurses to find your veins during the test.

When it’s time for your blood test:

  1. The nurses will prepare the clinic room and have everything ready that they will need
  2. It is normal to feel a little anxious about the test - it’s a good idea to tell the nurses this so that they can help to reassure you. If you are feeling very worried, you may be asked if you would like to see a play specialist, who can help to keep you busy and feel calmer
  3. You will be offered numbing cream or freeze spray to put on the place where the blood will be taken, usually the inside of your elbow, or the back of your hand. These help to stop you feeling the blood test being done 
    • Numbing cream (sometimes called EMLA cream) is a type of anaesthetic. You put it on your arm (or hand) about an hour before your blood test, and cover it with plastic wrap whilst it gets to work. It makes your skin numb, which can help to make it more comfortable when the needle goes in
    • Freeze spray (cool spray) can be sprayed onto your skin just before your blood test. The nurse will squirt the icy cold spray onto your skin. It can numb your skin briefly to make it more comfortable when the needle goes in
    • You can choose not to have numbing cream or freeze spray - some children prefer not to
  4. If you had numbing cream the nurse will wipe off the cream, and make sure your skin is completely clean
  5. A tourniquet (a tight band of material) will be put around the top of your arm - this doesn't hurt, and it helps to make your veins stand out so they are easier to find. You may also be asked to clench your hand, or squeeze a ball
  6. The nurse will insert a very small needle into a vein. The needle is connected by a thin plastic tube to a syringe. The syringe will draw your blood up the tube and into a small container. The nurse might need to fill more than one container, but the container can be swapped without moving the needle
  7. Once enough blood has been taken, the nurse will loosen the tourniquet on your arm, and gently remove the needle. A piece of cotton wool will be pressed down on the place where the needle was - this will stop the flow of blood. You will then have a plaster put on to protect the area and keep it clean

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What happens to my blood next? 

Your blood samples will be sent to the laboratory. Some results will be back within 24 to 48 hours, but some samples, including those that are monitoring certain medicines, may need to be sent to other hospitals and can take two to three weeks to come back. 

Your IBD team will check your results. If the results show that nothing needs to be changed, usually you will not be contacted. However, if your results show something clinically significant (something that means a change in your treatment may be necessary) your IBD team will call you to discuss what to do next.

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