Bone marrow test

Bone marrow is the soft tissue inside bones that is responsible for producing new blood cells. A bone marrow test (or biopsy) is a procedure that doctors use to examine the bone marrow inside certain bones.

The bone marrow test can either be an aspirate (where a sample of semi-liquid bone marrow is taken) or a trephine (where a sample of solid bone marrow is taken).

Why does my child need a bone marrow test?

By looking closely at your child’s bone marrow under a microscope, doctors will be able to find out more about your child’s blood cells.

In particular, they will look at the number and type of cells that make-up the blood, such as red or white blood cells, and platelets.

Your child’s doctor will explain in more detail why they think your child needs this test.

We have a tailored page for young people explaining what the bone marrow test entails.

What happens before the test?

You will have received information about how to prepare your child for the test in your admission letter or from the ward staff.

In children and young people, a bone marrow test is carried out while your child is under general anaesthetic. Your child should not eat or drink for the time specified. If you do not follow these instructions, the test may be delayed or even cancelled.

The person bringing your child for the procedure should have ‘Parental Responsibility’ for them. Parental Responsibility refers to the individual who has legal rights, responsibilities, duties, power and authority to make decisions for a child. If the person bringing your child does not have Parental Responsibility, we may have to cancel the procedure.

On the day of the test, the doctor will explain the procedure in more detail, and discuss any worries you might have. An anaesthetist will also visit you to explain about the anaesthetic. If your child has any medical problems, for instance, allergies, please tell the doctors about these.

What does a bone marrow test involve?

Once your child is under anaesthetic, the doctor will insert a hollow needle into one of their bones. This is usually the top of the pelvis or, for small babies, the leg may occasionally be used. The doctor will then draw off the aspirate (semi-liquid bone marrow) or trephine (solid bone marrow).Are they any risks involved?

Are they any risks involved?

Every anaesthetic carries a risk, but this is small. Your child will be given the anaesthetic by a doctor (anaesthetist) who is specially trained to deal with any complications. After an anaesthetic some children may feel sick or vomit. They may have a headache, sore throat, feel dizzy or be upset. These side effects are short lived and not severe.

The area around the biopsy site may be sore and bruised after the biopsy. This will disappear in time, and we will make sure your child is not in pain. There is also a very small risk that the biopsy site could become infected. This is extremely unusual but can be treated with antibiotics.

When will I get the results?

You will receive the results of the biopsy as soon as possible.

What happens after the test?

Your child will be able to recover from the biopsy on the ward. It is possible that your child will feel sick and vomit when they have come round from the anaesthetic. If this happens, we will wait until they can keep a drink down before trying to eat again. Try to encourage your child to drink fluids, but do not force them to do so.

The area where the needle was inserted will be covered with a plaster. You should remove this 24 hours after the test. You child can have a bath or shower immediately if they want. If your child is in pain, please give paracetamol according to the instructions on the bottle, unless you have been advised otherwise.

When will my child be able to go home?

Your child will be able to go home the same day as the test. It is fine for your child to attend school the day following the procedure. However, we advise that your child avoids PE or sports for a week.

You should call your GP or the hospital if:

  • the biopsy site bleeds
  • the biopsy site oozes a lot of fluid
  • your child is not drinking fluids

Further information and support

Call the GOSH switchboard on 07405 9200 and ask for the ward from which your child was discharged.

Compiled by:
The Bone Marrow Transplant team in collaboration with the Child and Family Information Group
Last review date:
September 2022