What Is a Sickle Cell Anemia Test?

A sickle cell anemia test is performed to evaluate if a person has sickle cell anemia disease or the sickle cell gene, which is an inherited trait. In the United States, a sickle cell anemia test is now a required part of the newborn screening process, but in many other countries they test is only performed after the physician has identified the child’s risk of carrying the sickle cell gene. A sickle cell anemia test can be performed on a fetus after the 10th week of pregnancy, or a blood test is completed once a baby is born. Adults who are unsure if they carry the gene can also be tested. Other ways to confirm the sickle cell anemia diagnosis include a hemoglobin S solubility test and a hemoglobinopathy evaluation.

One type of sickle cell anemia test is performed on an unborn fetus. A physician will insert a needle through the abdomen to extract a sample of the amniotic fluid, and then he or she will perform a DNA analysis of the fluid to determine if the fetus has a gene mutation. There are certain risks associated with this procedure.

A blood sample can also be taken from the heel or finger of an infant after birth to test for the trait or disease. It is a good idea for expecting parents to be tested for the gene, and both must be carriers for the disease to develop in a child. Blood examined will show sickle, or crescent-shaped red blood cells. These abnormally-shaped cells cannot carry enough oxygen for the various organs of the body, and sometimes the cells can cause clogged blood vessels.

If a person’s results of the sickle cell anemia test shows high levels of sickle cells, further testing can be performed to confirm the diagnosis that the person is a carrier of the defective gene, known as hemoglobin S. A hemoglobin S solubility test, perfomed with a sodium metabisulfite test, is conducted by decreasing the level of oxygen in the blood by adding in foreign substances. This test cannot be performed on infants who are less than 6 months old, and it will only show that the person has the sickle cell trait.

There are numerous types of hemoglobin found in the blood. A hemoglobinopathy evaluation will determine the levels of normal and abnormal hemoglobin variants present. Those who carry the sickle cell trait and those with the disease will produce hemoglobin S, and this test will be able to determine if the levels of the hemoglobin variant are high enough to indicate the presence of the disease.