The first step in diagnosing acute lymphoblastic leukaemia is to check for physical signs of the condition, such as swollen glands, and to take a blood sample.

If the blood sample contains a high number of abnormal white blood cells, it could be a sign of acute leukaemia. Your GP will refer you to a doctor who specialises in treating blood conditions (haematologist).

Bone marrow biopsy

To confirm a diagnosis of acute lymphoblastic leukaemia, the haematologist will take a small sample of your bone marrow to examine under a microscope.

The haematologist will use a local anaesthetic to numb the skin over a bone – usually the hip bone – before removing a sample of bone marrow using a needle. You may experience some pain once the anaesthetic wears off and some bruising and discomfort for a few days afterwards.

The procedure takes around 30 minutes and you should not have to stay in hospital overnight. You will have a dressing over the area of your body where the bone marrow was removed. You will need to keep this dressing on for 24 hours.

The bone marrow will be checked for cancerous cells and, if any are found, the type of acute leukaemia will be determined at the same time.

Some people with acute lymphoblastic leukaemia will need to have a bone marrow assessment to check for cancerous cells every 3 months for at least 2 years during maintenance treatment, or after having a bone marrow transplant.

Further tests

Several other tests can be done to find out about the progress and extent of leukaemia. These tests can also help to guide treatment.

Cytogenetic testing

Cytogenetic testing involves identifying the genetic make-up of the cancerous cells in a sample of blood, bone marrow or another type of tissue. Specific genetic variations can happen during leukaemia and knowing what these variations are can have an important impact on treatment.


Immunophenotyping is a test to help identify the exact type of acute lymphoblastic leukaemia. A sample of blood, bone marrow or another type of fluid is studied.

This testing is important as treatments may be slightly different for each type of acute lymphoblastic leukaemia.

Polymerase chain reaction (PCR)

A polymerase chain reaction (PCR) test can be done on a blood sample. PCR can help diagnose and monitor the response to treatment.

The blood test is repeated every 3 months for at least 2 years after starting treatment, then less often once remission is achieved.

Lymph node biopsy

If you've been diagnosed with acute lymphoblastic leukaemia, further biopsies may be done on any enlarged lymph nodes you have. These will establish how far the leukaemia has spread.

CT scans

If you have acute lymphoblastic leukaemia, a CT scan may be used to assess how far the leukaemia has spread and to check that your organs, such as your heart and lungs, are healthy.

Chest X-ray

You may have an X-ray of your chest to check for any swollen lymph nodes.

Lumbar puncture

lumbar puncture may be done if there's a chance that acute leukaemia has spread to your nervous system.

A needle is inserted into the lower part of your spine to extract a small sample of the fluid that surrounds and protects your spine (cerebrospinal fluid), which is tested for cancer cells.