Screening and diagnosis of Sickle Cell Disease?

A blood test can check for hemoglobin S — the defective form of hemoglobin that underlies sickle cell anemia. In most states in the United States, this blood test is part of routine newborn screening done at the hospital. But older children and adults can be tested too.

In adults, a blood sample is drawn from a vein in the arm. In young children and babies, the blood sample is usually collected from a finger or heel. The sample is then sent to a laboratory, where a technician can screen for hemoglobin S.

If the screening test is negative, there is no sickle cell gene present. If the screening test is positive, the technician will conduct further tests to determine whether one or two sickle cell genes are present. People who have one gene — sickle cell trait — have a fairly small percentage of hemoglobin S. People with two genes — sickle cell disease — have a much larger percentage of the defective hemoglobin.

Additional steps

To confirm any diagnosis, a sample of blood is examined under a microscope to check for large numbers of sickle cells — a marker of the disease. If you or your child has the disease, a blood test to check for anemia — a low red blood cell count — will be done.

If you or your child has sickle cell anemia, you'll likely be referred to a doctor who specializes in blood-related diseases (hematologist). And your doctor may suggest additional tests to check for possible complications of the disease. If you or your child carries the sickle cell gene, you may be referred to a genetic counselor — an expert in genetic diseases.

It's possible to detect sickle cell anemia in an unborn baby by sampling some of the fluid surrounding the baby in the mother's womb (amniotic fluid). A test can determine whether an unborn baby has sickle cell anemia or carries the sickle cell gene (sickle cell trait).

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