What to Know About a Sickle Cell Test

Medically Reviewed by Sanjay Ponkshe on July 13, 2023
4 min read

Sickle cell tests have become routine in newborn screenings, but older children and adults may need to be tested as well. Read on to see if you or a loved one might benefit from being tested for sickle cell.

A sickle cell test is a blood test that checks for abnormal red blood cells called sickle cells. These can cause sickle cell disease or sickle cell trait.  

Sickle cell disease is an inherited disorder. It affects a protein in your red blood cells that carries oxygen to your tissues. The protein is called hemoglobin.  

Healthy red blood cells are round and flexible, which helps them move easily in your blood. With diseased hemoglobin, cells don't get the oxygen they need. They change shape and look like the letter C, a sickle shape.

The cells get stuck together, which can lead to pain as well as blockages in your blood. Sickle cells don’t live very long, and they are often broken down by your spleen. You become anemic: you lose red blood cells, and your body loses oxygen.

If you have a family history of sickle cell disease, you are more likely to have the disease. If you carry the sickle cell gene but don't get sick, you have sickle cell trait. Though you may live a healthy, normal life, you can pass the gene on to your children.

Certain groups of people are more likely to be at risk, but all babies are screened for sickle cell disease right after birth. This is part of routine testing at the hospital. 

Your doctor might want to order a sickle cell test for you if:

  • You are a prenatal patient and either you or the other parent has sickle cell trait or hasn’t been tested
  • You are an immigrant and haven’t been tested before
  • Your family history is unknown
  • You have symptoms 

Except for prenatal screens, most sickle cell tests are simple blood tests. 

Complete blood count. This blood test, called a CBC, screens for anemia and lots of other conditions. It measures the number of some types of cells in your blood. It can identify abnormal hemoglobin. ‌

Peripheral smear. This is a blood test that looks at the shape and number of your red and white blood cells. Some of your blood is put on a slide and examined by computer or under a microscope to identify sickle-shaped cells. This test is usually done for children and adults along with a CBC. ‌

A peripheral smear is also called a blood smear, peripheral blood film, manual differential, or manual diff. 

Hemoglobin electrophoresis. This is a blood test that looks at the types of hemoglobin in your blood. A current is applied to the blood sample, which separates blood into bands of hemoglobin. There are lots of different types of hemoglobin, but hemoglobin S and some others are associated with sickle cell disease. 

This is a routine test for newborn screening but is also done for children and adults. 

Sickle turbidity test. Also called hemoglobin solubility, this is an inexpensive test where blood is added to a solution. If hemoglobin S is present, the test turns cloudy, or turbid, as it is exposed to the solution. 

Sickle turbidity testing can often have false positives. So when a sickle turbidity test is positive, another test is usually done to double-check the results. 

DNA testing. Prenatal DNA testing for sickle cell disease or sickle cell trait looks at your baby’s DNA instead of the blood. It’s recommended for people who are carriers, who have a family history of sickle cell disease, or who have an unknown family medical history.

You can have a chorionic villi test done between 10 and 12 weeks in your pregnancy. This test involves taking a small amount of tissue from your placenta. ‌

Around 14 to 16 weeks, you can have your amniotic fluid tested. This test is called an amniocentesis and involves placing a needle into your womb to draw out fluid.‌

Bone marrow tests. In rare cases, your doctor might take some of your bone marrow with a needle. Bone marrow is the spongy tissue inside your bones where blood cells are made.

This test doesn’t diagnose sickle cell disease, but your doctor might do it to figure out other problems, especially if you have a severe infection. 

Sickle cell testing usually involves simple blood tests that are easily carried out. Ask your doctor if you think a test might be appropriate for you. Newborn screening can identify the health condition early and help with treatment that can protect your baby's and, going forward, your family's health.