Chronic Myeloid Leukemia (CML): Diagnosis 

How is chronic myeloid leukemia (CML) diagnosed?

If your healthcare provider thinks you might have CML, you will need certain exams and tests to be sure. Your healthcare provider will ask you about your health history, your symptoms, risk factors, and family history of disease. Your healthcare provider will also give you a physical exam.

What tests might I need?

You may have one or more of the following tests:  

• Blood tests. CML is often found with blood tests before you have symptoms. Blood is taken from the arm or hand with a needle. Tests can look at the numbers of different types of blood cells. People with CML often have too many white blood cells.

• Bone marrow aspiration and biopsy. This procedure is done by taking small amounts of bone marrow fluid (aspiration), solid bone marrow tissue (core biopsy), or both. Bone marrow samples are usually taken from the back of the hip (pelvic) bone. For the bone marrow aspiration, the area over the hip is numbed. A thin, hollow needle is inserted into the pelvic bone. A syringe is used to pull out a small amount of liquid bone marrow. You may have some brief pain when the marrow is removed. A bone marrow biopsy is usually done just after the aspiration. A slightly bigger needle is used to take out a small core of bone and marrow. The biopsy may also cause some brief pain. The fluid and bone marrow are looked at for the number, size, and maturity of blood cells and abnormal cells. Other tests can also be done on these cells.

How blood or bone marrow is tested 

Nearly all CML has a genetic change called the Philadelphia chromosome, an abnormal gene called BCR-ABL, or both. People with CML also have too many white blood cells. Tests are used to look for these changes. The tests done on blood or bone marrow samples may include:                                                                                                                                                            

• Cytogenetics. For these tests, cells are grown in a lab for a week or more. The chromosomes inside the cells are then stained with special dyes and viewed with a microscope. Major problems in the chromosomes can often be seen. But smaller changes may not be visible. These tests usually take a few weeks. This is because the cells need time to be grown in the lab.

• Fluorescence in situ hybridization (FISH). This test is another way to look for changes in chromosomes. The cells in the sample are stained with fluorescent dyes that will only attach to certain parts of chromosomes. The cells are then viewed with a microscope using a special light. This test can find some chromosome changes that can't be seen with standard cytogenetic testing. It's also a quicker test. 

• Polymerase chain reaction (PCR). This is a very sensitive test that can detect very low levels of leukemia cells in a test sample. It works by increasing the amount of genetic material in a sample so that it can be detected. This test can find small levels of chromosome changes such as the BCR-ABL gene that other tests may not find.  

Getting your test results

When your healthcare provider has the results of your tests, he or she will contact you with the results. Your provider will talk with you about other tests you may need if CML is found. Make sure you understand the results and what follow-up you need.