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Diagnosis Hematology & Blood & Marrow Transplant (BMT)

Myelodysplastic Syndromes

MDS is generally diagnosed when a patient is evaluated for low blood counts, although in some MDS patients, the white blood count, platelet count, or both may be elevated. The hallmark feature of MDS is a bone marrow aspirate and biopsy that reveals heavy infiltration with abnormal-looking bone marrow cells. (Myelodysplasia means "funny-looking bone marrow.") A chromosome analysis, called cytogenetics, is performed on the bone marrow sample.

In patients with MDS, immature cells called blasts make up less than 20 percent of the cells in the bone marrow. If blast cells make up more than 20 percent, the patient is diagnosed with acute myeloid leukemia.

Subtypes of MDS

MDS has been classified into several different subtypes, which are largely determined by the percentage of blast cells in the bone marrow:

  • Refractory anemia (RA) or refractory anemia with ringed sideroblasts (RARS) 5 percent or less blast cells
  • Refractory anemia with excess blasts (RAEB) 5 to 19 percent blast cells, a white blood cell count of less than 13,000 per microliter, and blood monocytes greater than 1,000 per microliter.

In a special subtype of RA or RARS, the patient is missing the long arm of chromosome five. Patients with this subtype tend to respond well to treatment with lenalidomide (Revlimid) and to survive a long time.


After diagnosis with MDS, prognosis is determined by the blood counts (red blood cells, white blood cells and platelets), the types of chromosome abnormalities in the MDS cells, and the percentage of blast cells in the bone marrow.

The average survival, based on risk scores, are as follows:

  • Low risk — 5.7 years
  • Intermediate-1 risk — 3.5 years
  • Intermediate-2 risk — 1.2 years
  • High risk — 0.4 years

UCSF Health medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider.