A sickle cell screening test is a blood test designed to identify abnormal hemoglobin, specifically hemoglobin S, linked to sickle cell trait or sickle cell disease. The test determines if an individual carries the gene for sickle cell hemoglobin, indicating they have the trait (are a carrier) or the full disease (two copies of the abnormal gene).
Why Screening Matters
Early detection of sickle cell trait or disease through screening offers significant benefits, enabling timely intervention and management of potential health complications. For newborns, early diagnosis allows for the initiation of preventative treatments, such as prophylactic oral penicillin, which substantially reduces the risk of serious infections in the first few years of life. This early knowledge also facilitates access to appropriate medical care and parental education regarding early warning signs of infection. Beyond individual health, screening provides information for informed family planning decisions and access to genetic counseling.
Who Should Get Screened
Sickle cell screening is widely recommended for specific populations to ensure early identification. All newborns in the United States undergo universal screening for sickle cell disease as part of routine hospital testing, typically within 24-48 hours after birth. Pregnant individuals are also advised to receive screening to assess the risk for their baby, ideally before 10 weeks of pregnancy to allow time for further testing if needed. Screening is also advised for individuals with a family history of sickle cell disease or trait, or those from ethnic backgrounds with a higher prevalence of the condition, such as African, Mediterranean, South Asian, Caribbean, and Hispanic descent. Anyone concerned about their status can request a blood test from their doctor.
How the Test is Performed
A sickle cell screening test typically involves collecting a blood sample. For newborns, this is commonly done through a heel stick, where a small lancet punctures the baby’s heel to collect several drops of blood. For older children and adults, a blood sample is usually drawn from a vein, often in the arm, by a healthcare professional using a needle. Once collected, the blood sample is sent to a laboratory for analysis. Lab techniques such as high-performance liquid chromatography (HPLC) or hemoglobin electrophoresis are used to identify and measure the different types of hemoglobin present in the blood, specifically looking for abnormal hemoglobin variants like hemoglobin S.
Understanding Your Results
The results of a sickle cell screening test provide important information about an individual’s hemoglobin type. A negative result indicates the absence of hemoglobin S, suggesting normal hemoglobin and no sickle cell trait or disease.
Sickle Cell Trait
If the test indicates sickle cell trait, it means the individual is a carrier, possessing one copy of the abnormal hemoglobin S gene and one copy of the normal hemoglobin gene. Individuals with sickle cell trait usually do not experience symptoms of sickle cell disease and generally live a normal life. However, if two carriers have children, there is a 1 in 4 chance with each pregnancy that their child could inherit two copies of the abnormal gene and develop sickle cell disease. Genetic counseling is recommended for carriers to understand these inheritance patterns and family planning options.
Sickle Cell Disease
If sickle cell disease is suggested, confirmatory tests like DNA analysis are performed to determine the specific type. Individuals are then referred to a specialist, such as a hematologist, for comprehensive management, including ongoing monitoring and preventive treatments.