Tests for chronic myeloid leukaemia (CML)

You usually have a number of tests to check for chronic myeloid leukaemia (CML). Your doctor may suspect or sometimes diagnose leukaemia from a blood test. You then might have more tests to confirm your diagnosis and find out more about the type of leukaemia you have.

CML is a type of blood cancer. It starts from blood cells called myeloid stem cells Open a glossary item in the bone marrow. The bone marrow is the soft inner part of the bones where new blood cells are made.

Diagram of bone marrow

CML is different from acute myeloid leukaemia (AML). AML tends to develop quickly and gets rapidly worse if it is not treated. CML usually develops very slowly.

We have separate information about the tests you might have for AML and other types of leukaemia.

Tests your GP might do

CML tends to develop slowly, so most people don’t have any symptoms. People are often diagnosed after having a routine blood test for something else.

If you see your GP, they might do some tests to help them decide if you need to see a specialist. The tests they might do include:

  • physical examination

  • blood tests

Depending on the results of your examination and blood tests, your GP may also arrange for you to have other tests such as an x-ray or ultrasound scan. You usually have these tests at your local hospital.

Physical examination

Your doctor usually asks you to lie or sit down. They look at and feel your skin all over your body to check for any abnormalities or areas that are swollen. Things they look for include signs of bleeding, bruising and infection.

They may also listen to your chest and tummy (abdomen) to find out if they sound normal.

You can ask for someone else to be in the room with you if you want, to act as a chaperone. A chaperone is a trained healthcare professional such as a nurse. A friend or relative can also stay with you for support. They can be with you during the examination. 

Blood tests

Blood tests can check your general health including:

  • how well your liver and kidneys are working
  • the number of blood cells in your blood such as white blood cells, Open a glossary item platelets Open a glossary item and red blood cells. You may hear this being called a full blood count Open a glossary item
  • if you have any signs of infection

Tests your specialist might do

Depending on your symptoms and the results of your blood tests, your GP might arrange for you to go to the hospital. Sometimes this is quite quick, and you might have to go there straight away. This can happen if your GP suspects that you have leukaemia.

The specialist you see at the hospital is called a haematologist. This is a doctor who specialises in diseases of the blood such as leukaemia.

Your specialist usually repeats the blood tests done by your GP. You also have more tests such as:

  • tests on blood sample cells. This is also called immunophenotyping
  • a bone marrow test
  • tests to look for changes in the genes Open a glossary item and chromosomes Open a glossary item of your leukaemia cells
  • scans such as an x-ray and an ultrasound scan
  • tests to look at substances on the surface of cells and tissues. These are called tissue typing tests


Immunophenotyping are tests to look for certain proteins on the surface of the leukaemia cells. This is one of the most important tests you have. The results are usually all your doctor needs to confirm a diagnosis of CML.

A specialist laboratory does these tests. Sometimes doctors use a technique called flow cytometry to do immunophenotyping.

Immunophenotyping is usually done using blood samples. But your doctors may also use bone marrow samples.

These tests can also help to find out how well treatment is working and if your leukaemia has gone away after treatment.

Bone marrow test

You have this test to check whether there are cancer cells in your bone marrow. It can help to find out more about the type of CML you have.

You usually have this test under local anaesthetic. This means that you are awake but the area is numb.

During a bone marrow biopsy, your doctor or specialist nurse uses a needle to take a sample of bone marrow. They may use a second needle to take out a piece of more solid bone marrow tissue. They usually take these samples from the back of your hip bone.

Diagram showing a bone marrow biopsy

A specialist doctor called a pathologist Open a glossary item looks at the tissue under a microscope.

Tests to look for changes in the genes and chromosomes

There are different tests that look for changes in the genes and chromosomes of your leukaemia cells. These are also called genetic tests.

The genetic tests look for 2 changes in particular:

  • the Philadelphia chromosome

  • the BCR-ABL gene

These tests can help your doctor find out more about the type of CML you have. It can also help doctors see how well your treatment is working.


You may have some scans to check for CML and signs of infection.

Chest x-ray

An x-ray is a test that uses small amounts of radiation to take pictures of the inside of your body. They are a good way to show changes in organs such as the lungs.

You might have a chest x-ray to check for signs of infection if you have any symptoms.

Ultrasound scan

Ultrasound scans use sound waves to create a picture of a part of the body. You might have an ultrasound scan to look for changes in your spleen Open a glossary item or liver. 

You may not need this test if your doctor can feel that your liver or spleen is larger than it should be.

Tissue typing tests

Tissue typing is a set of tests that you have using a sample of your blood and saliva. You might have it if your doctors think that you need treatment with a stem cell transplant using a donor’s stem cells. This is called an allogeneic transplant.

Tissue typing tests can show how closely a possible stem cell donor’s tissue matches your own.


The tests you have help your doctor find out if you have leukaemia and the type of leukaemia you have.

This is important because doctors use this information to recommend the best treatment for you.


Coping with a diagnosis of CML can be difficult. There is help and support available for you and your family.

  • A British Society for Haematology Guideline on the diagnosis and management of chronic myeloid leukaemia
    G Smith and others
    British Journal of Haematology, 2020. Vol 191, Issue 2. Pages 171-193

  • Chronic myeloid leukaemia: ESMO clinical practice guidelines for diagnosis, treatment and follow up
    A Hochhaus and others
    Annals of Oncology, 2017. Vol 28, Supplement 4. Pages 41-51

  • Routes to diagnosis, 2018
    NHS Digital, 2022

  • Suspected cancer: recognition and referral
    National Institute of Health and Care Excellence (NICE), 2015 (last updated October 2023)

  • Scottish referral guidelines for suspected cancer
    NHS Scotland, last updated October 2022

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact patientinformation@cancer.org.uk with details of the particular issue you are interested in if you need additional references for this information.

Last reviewed: 
19 Mar 2024
Next review due: 
19 Mar 2027

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