How is MDS diagnosed?
Low blood counts may be picked up by a simple test called a full blood count. If anything abnormal is seen on the blood count, you will be referred to a blood specialist. This doctor is called a haematologist. He or she will ask you about your medical history to rule out other causes of low blood counts. These tests will find out what type of MDS you have:
- Physical exam
- Full blood count
- Bone marrow tests
- Chromosome studies (cytogenetics)
These tests are usually done as an outpatient.
Physical exam: You will be given a full physical exam. It is important for your haematologist to check your general health and also to check for any signs of disease. He or she will note any previous illnesses and treatment, and details about your lifestyle.
Full blood count: A full blood count (FBC) will be taken. This finds out the levels of the different types of cells in your blood. If anything abnormal is seen on the blood count, the laboratory will then examine the blood cells under the microscope. This is called a blood film exam.
Bone marrow tests: A bone marrow test is usually needed to confirm the diagnosis of MDS. Bone marrow tests involve taking a tiny sample of your bone or bone marrow and looking at it under a microscope. The sample is taken from the inside of the bone, usually your hipbone. If a sample of bone marrow cells is taken, it is called an aspirate. If a tiny piece of bone or solid marrow is taken, it is a trephine biopsy. Both can be done at the same time.
Your doctor will give you a local anaesthetic to numb the area beforehand. The biopsy itself may be uncomfortable and can last up to 10 minutes, while the entire procedure can take about 30 minutes. Once the needle is put into your bone cavity, a sample of your bone marrow is drawn into a syringe. Bone marrow looks like a red liquid similar to blood. A different kind of needle is used to do the trephine biopsy.
When it is over, a small plaster is put on the area where the bone marrow has been taken. You may be asked to lie on your back for 10‒15 minutes to stop any possible bleeding. You can take mild painkillers, like paracetamol, if you feel any discomfort later. The bone marrow sample is examined under the microscope to look for changes seen in MDS. Other tests are often needed on the bone marrow sample. This includes chromosome studies called cytogenetics. Marrow tests may be repeated later to check how well you are responding to treatment or to see how the disease is behaving.
A bone marrow test is usually needed to confirm the diagnosis of MDS.
Chromosome studies (cytogenetics): Chromosome tests can find out the number and shape of the chromosomes in your bone marrow cells. In your body there are 23 pairs of chromosomes. These chromosomes contain the genetic information about the cells in your body. This information is sometimes also called the karyotype. The chromosomes in the bone marrow sample are compared to those in normal cells. In MDS, there may be some genetic changes in the marrow cells which help to confirm the diagnosis of MDS and also predict the outcome (prognosis). Remember these chromosome changes occur when the disease develops and are only found in your bone marrow and blood cells, so they cannot be passed on to your children.
Waiting for results
It may take a few weeks to get all your test results back. Your blood and bone marrow will be checked by both haematologists and doctors who specialise in studying cells and tissues. These doctors are called pathologists and can find out which type of MDS you have. Cytogenetic tests may take a little longer. Once all your tests are ready, your haematologist and you will decide what type of treatment you should have.
MDS can be a difficult diagnosis to make. Sometimes if your doctor is unsure if there is definite MDS, your blood counts will be watched for a few months, and the marrow test may then be repeated.
Naturally, waiting for results can be an anxious time for you. Do share your worries with a family member or close friend. Do call the National Cancer Helpline on 1800 200 700 if you have any queries or concerns or visit a Daffodil Centre.