Tests for chronic lymphocytic leukaemia (CLL)

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

CLL starts from white blood cells called lymphocytes 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

CLL is different from acute lymphocytic leukaemia (ALL). ALL tends to develop quickly and get rapidly worse if they are not treated. We have separate information about the tests for ALL and other types of leukaemia.

Tests your GP might do

CLL 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:

  • blood tests

  • a physical examination

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. 

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

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. 

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. These might include:

  • tests on blood sample cells
  • a bone marrow test
  • tests to look for changes in the genes of your leukaemia cells
  • scans such as CT scan, x-ray and an ultrasound scan
  • testing your lymph nodes Open a glossary item for CLL. This is a lymph node biopsy
  • tests to look at substances on the surface of cells and tissues. These are called tissue typing tests
  • tests to check for infection

Tests on the blood sample cells

Your doctor usually does a number of checks on the blood sample cells. These are immunophenotyping tests.

Immunophenotyping 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 CLL.

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

Immunophenotyping tests are 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 may have this test to check whether there are cancer cells in your bone marrow. It can confirm if you have CLL and help to find out more about the type of CLL 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

There are different tests that look for changes in the genes of your leukaemia cells. Your doctor can do these tests on your blood and bone marrow samples.

Genetic tests can look for changes in specific genes such as the:

  • TP53 gene

  • IGHV gene

These tests help your doctor understand more about the type of leukaemia you have. This helps them make decisions about your treatment.


You may have some scans to check for CLL 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.

CT scan

A CT scan uses x-rays and a computer to create detailed pictures of the inside of your body.

CT scans can help your doctor find out if you have CLL in organs such as your spleen Open a glossary item. You may also have a CT scan after treatment to check how well it is working.

You may not need to have a CT scan if you don’t have any symptoms of CLL.

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 or liver. 

Lymph node biopsy

It is not very common to test your lymph nodes for CLL. This is because your doctor can usually diagnose CLL from blood tests.

You might have a lymph node biopsy if, after blood and bone marrow tests, your doctor is unsure about your diagnosis.

You may also have a lymph node biopsy if your doctor thinks your leukaemia is changing (transforming) into a type of lymphoma Open a glossary item called Richter’s syndrome.

Your doctor either removes the whole lymph node or part of it. They send it to the laboratory for testing. You usually have this test under local anaesthetic.

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 Open a glossary item using a donor’s stem cells. This is called an allogeneic transplant.

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

Tests to check for infection

CLL and its treatment can weaken your immune system Open a glossary item. This is because it stops your bone marrow from making blood cells that help fight infection. This increases your risk of getting an infection.

You have blood tests to check for specific viruses before you start treatment. This helps your doctor know your risk of developing these viruses during treatment or the risk of them flaring up.

Your doctor might test for:

  • cytomegalovirus (CMV)

  • hepatitis B virus (HBV)

  • hepatitis C virus (HCV)

  • human immunodeficiency virus (HIV)


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 CLL can be difficult. There is help and support available for you and your family.

  • Chronic lymphocytic leukaemia: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow up
    B Eichorst and others.
    Annals of Oncology, 2021, Volume 32 Issue 1 pages 22-33

  • 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

  • iwCLL guidelines for diagnosis, indications for treatment, response assessment, and supportive management of CLL
    M Hallek and others
    ASH publications, 2018. Vol 131, Issue 25

  • 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: 
18 Mar 2024
Next review due: 
18 Mar 2027

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