Tests for childhood acute lymphoblastic leukaemia (ALL)

Bone marrow tests

Your child has this test to check whether there are leukaemia cells in the bone marrow. And what type of leukaemia it is. Bone marrow is spongy tissue and fluid that is inside your bones. It makes your ​blood cells​ .

How does your child have a bone marrow test?

A doctor or specialist nurse removes a sample of bone marrow fluid (called a bone marrow aspirate). Or a small piece of bone marrow (called a trephine). Your child might have both tests at the same time.

This sample is usually taken from the back of their hip. In small infants they might have it from their shinbone (tibia). This information is about a child having it from their hip bone.

Doctors send the sample to the laboratory. A specialist doctor called a pathologist looks at the cells or tissue under a microscope.

Most children usually has this test under general anaesthetic in theatres. Some older children may have it performed under sedation and local anaesthetic.

After the bone marrow test

Your child returns to the children’s ward after the test. Their nurse will look after them closely when they return and take regular measurements such as their:

• heart rate

• breathing rate

• blood pressure

• oxygen levels

• temperature

This is to make sure they are recovering from the sedation or anaesthetic. The nurses also usually check that your child has:

• had something to drink

• had something to eat or some milk

• had a wee

• a clean and dry dressing over the site of the test

A bone marrow biopsy is a safe test. Your child’s doctor or nurse talks with you about any possible problems they might have after it.

Spinal fluid test (lumbar puncture)

A lumbar puncture is a test to check the fluid that circulates around the brain and spinal cord. This is called cerebrospinal fluid or CSF. A lumbar puncture checks for leukaemia cells in the CSF. Using a special needle your child’s doctor, or specialist nurse, takes a sample of the CSF from their lower back.

Your child’s team will talk you through the benefits and risks of having a lumbar puncture. There is a risk of bleeding and infection, but this is very rare.

How does your child have a lumbar puncture?

Most children have a general anaesthetic for this test. But occasionally some older children might be able to have local anaesthetic for their lumbar puncture. 

Sometimes the area where the needle goes in, is numbed with a local anaesthetic. If your child has this test under local anaesthetic they might feel some pressure and a slight soreness when the local anaesthetic needle goes in. 

The doctor or nurse puts the lumbar puncture needle in through the skin. If your child has a local anaesthetic they wait for the area to get numb first.

The lumbar puncture needle goes into the small of the back and into the space around the spinal cord.

Once it's in the right place, the fluid drips out into a pot. You also usually have intrathecal chemotherapy at the same time. This is an injection of methotrexate chemotherapy into the spinal fluid. It helps to treat and prevent any cancer cells spreading to the cerebrospinal fluid.

The doctor or nurse takes the needle out and puts a dressing or plaster on your child’s back.

After the lumbar puncture

After the lumbar puncture your child returns to the children's ward. Their nurse will look after them closely when they return and take regular measurements such as their:

• heart rate

• breathing rate

• blood pressure

• oxygen levels

• temperature

This is to make sure they are recovering from the anaesthetic. The nurses also checks that your child has:

• had something to drink

• had something to eat or some milk

• had a wee

• a clean and dry dressing over the site of the test

The area might be a little sore or bruised that lasts for a couple of days.

Your child will need to lie flat for about an hour after the procedure to help prevent headaches and to help ensure the chemotherapy goes to all areas of the ​central nervous system​ .

Let your child’s healthcare team know if they get symptoms such as:

• a severe headache

• being sick

• their eyes are sensitive to bright light

• tingling or numbness in their legs

Your child usually has a bone marrow aspirate and lumber puncture together.

Genetic tests

There are different tests that look for changes in the ​genes​ and ​chromosomes​ of your child’s leukaemia cells. Genes are coded messages made of ​DNA​ that tell our cells how to behave. Chromosomes are made of a very long strand of DNA and contain many genes. These tests are sometimes called cytogenetic or molecular studies.

Fluorescence in situ hybridisation (FISH)

FISH is a test that looks for chromosome changes in cells. It can help your child’s doctor work out which treatment they need.

This test can check if they have the chromosome change that causes Philadelphia positive ALL. But there are also many other chromosome changes that are important in helping their doctor understand more about their leukaemia.

Find out more about FISH testing

We also have a 2 minute video that explains what Philadelphia positive leukaemia is.

Polymerase chain reaction (PCR)

PCR are tests that can pick up abnormal genes. It can tell if your child has Philadelphia positive ALL. This helps your child’s doctor work out the treatment they need. In leukaemia, it can also monitor how well the treatment is working.

Gene panels

A lot is known about the gene changes that can be seen in leukaemia cells. Doctors now commonly look for these gene changes in the DNA from your child’s leukaemia cells. This is called a gene panel.

Whole genome sequencing (WGS)

The aim of this test is to look for changes (mutations) in their genes. This test can help to identify children with specific gene changes that might be missed by the standard panels which cause them to not respond to treatment as well. Understanding these changes can help doctors find out what treatment will work best for them.

These tests are done at specialist laboratories around the UK. They are called genomic laboratory hubs.

For this test your child’s doctor sends some leukaemia cells from the bone marrow and also either a blood sample or a small amount of skin (skin biopsy). The skin biopsy is usually taken at the same time as their bone marrow test.

Chest x-ray

X-rays use high energy rays to take pictures of the inside of your body. Chest x-rays can show:

• fluid

• signs of infection

• an enlarged heart

• enlargement of the lymph glands in the chest, where leukaemia cells have collected

How does your child have an x-ray?

There is no special preparation for an x-ray. Your child usually has a chest x-ray standing up against the x-ray machine if they are old enough to stand. They have it lying on the x-ray couch if they are younger or unable to stand.

X-rays are painless and quick. Your child won’t feel or see anything. You are usually able to stay in the room when your child is having their x-ray. You need to wear a lead apron to protect you from the small amount of radiation.

Your child’s specialist makes sure the benefits of having an x-ray outweighs the risks of the small amount of radiation.

After the x-ray

Your child can usually eat, drink and play as normal after a chest x-ray.

Getting your child’s results

You get your child's test results quite quickly usually within 48 hours if not sooner. But some more complex tests such as looking for changes (abnormalities) in your child's ​genes​ can take a couple weeks or even longer.

Waiting for test results can be a very worrying time. You might have contact details for a children’s cancer specialist nurse and you can contact them for information if you need to. It can help to talk to a close friend or relative about how you feel.

You can also contact the Cancer Research UK information nurses for support on freephone 0808 800 4040. The lines are open from 9am to 5pm, Monday to Friday.