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Sickle Cell Test

Risks

Blood sample from a vein

There is very little chance of a problem from having a blood sample taken from a vein.

  • You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
  • In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
  • Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (such as Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.

Blood sample from a heel stick

Usually, there are no problems from a heel stick. A small bruise may develop. Babies with bleeding problems may bleed more with usual. Sometimes bleeding problems are found when blood is being collected for the sickle cell test.

Results

A sickle cell test is a blood test done to screen for sickle cell trait or sickle cell disease.

Sickle cell test 2
Normal:

Normal hemoglobin is present.

Abnormal:

Abnormal hemoglobin is present.

  • In sickle cell trait, more than half of the hemoglobin is normal (hemoglobin A) and less than half is abnormal (hemoglobin S).
  • In sickle cell disease, almost all hemoglobin is hemoglobin S with some hemoglobin called hemoglobin F.

In babies, a sickle cell blood test may be repeated at 6 months old, or a genetic information (DNA) test may be done.

What Affects the Test

Having a blood transfusion in the past 4 months can cause a false-negative test result because of the normal hemoglobin from the blood donor.

What To Think About

  • Most states routinely do a sickle cell blood test on all newborns.
  • If you have a family history of sickle cell disease, you may be advised to have a blood test to determine whether you carry the sickle cell trait. If you have sickle cell trait or sickle cell disease, you may choose genetic counseling before deciding to have children.
  • Testing is available to check for sickle cell disease in an unborn baby (fetus). This can be done through amniocentesis or chorionic villus sampling (CVS).
  • Babies younger than 6 months of age may have false-negative results because they have more hemoglobin F (fetal hemoglobin) in their blood.
  • In the United States, sickle cell disease mainly affects African Americans and Latin Americans.

WebMD Medical Reference from Healthwise

Last Updated: March 12, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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