When physicians suspect that a patient may have a myelodysplastic syndrome (MDS), they will obtain a detailed medical history and perform a physical examination.

A variety of tests may be ordered to diagnose, classify, and monitor the disease. Establishing the exact type of MDS is important because the different subtypes vary in their treatment and their prognosis. Samples of cells from the patient’s blood and bone marrow will be examined to verify the diagnosis. Additional tissue and cell samples may also be needed to guide treatment and determine if the disease is progressing into acute myeloid leukemia (AML).

Common tests include:

• Complete blood count (CBC) and blood smear. A CBC is a blood test that measures the number of red blood cells, white blood cells and platelets in a sample of blood, as well as the amount of hemoglobin in the red blood cells and a number of other factors. A blood smear is the examination of cells under a microscope. Changes in the numbers of blood cell types can suggest MDS.
  
  When examined under a microscope, blood cells from MDS patients may also have certain abnormalities in size, shape and other features. In addition, patients with the RAEB (refractory anemia with excess blasts) type of MDS may also have a small number of myeloblasts (an early form of white blood cell) in the blood.
  
  
• Bone marrow aspiration and biopsy. A bone marrow aspiration involves using a thin needle to collect a small sample of liquid bone marrow under local anesthesia. A bone marrow biopsy uses a larger needle to remove a piece of bone marrow. Usually performed at the same time, these procedures may be ordered to determine if a MDS is present and to classify the disease. In order for a diagnosis of a MDS to be made, a patient must have less than 20 percent blasts in the bone marrow. The procedures may also be ordered after diagnosis to monitor treatment or determine if the disease is progressing into AML.
  
  
• Cytochemistry. This procedure involves placing a sample of blood or bone marrow on glass microscope slides. The slides are then exposed to stains (dyes) that are attracted to certain chemicals present in some types of MDS cells. Although one stain may cause a particular type of MDS cell to appear with black spots when examined under a microscope, it does not cause color changes in other types of cells.
  
  
• Flow cytometry. This procedure uses fluorescent antibodies to detect certain molecules on the surface of MDS cells. If specific cells are present, the antibodies will give off light when the sample is passed in front of a laser beam. The cells are measured and analyzed by a computer for the presence of antibodies. This is a very accurate test for determining the exact type of MDS present in a patient.
  
  
• Immunocytochemistry (immunophenotyping). This procedure uses special antibodies to detect certain molecules on the surface of MDS cells. When specific cells are present, color changes can be detected under a microscope. As with flow cytometry, this test is used to help distinguish types of MDS from one another and from other diseases.
  
  
• Cytogenetics. This test uses a microscope to evaluate the characteristics of cells including their formation, function and structure. It may be ordered to determine if the cells have too many chromosomes or if the chromosomes have any abnormalities. Abnormalities commonly found in MDS cells include translocations (transfer of DNA from one chromosome to another), deletions (part of a chromosome is lost) and additions (part of a chromosome is duplicated and too many copies of it are found within the cell).
  
  
• Molecular genetic studies. These tests examine MDS cell DNA for translocations. In some cases, the tests may reveal translocations unable to be detected with cytogenic testing.

In addition to diagnosing and classifying MDL, cytogenetics and molecular genetic studies are also useful in determining a person’s risk of developing cancer. Genetic tests are available to identify some genetic abnormalities, and additional genetic tests are being developed.