Identifying sickle cell anaemia early and accurately is crucial for managing this inherited blood disorder throughout a person’s lifetime. Screening begins at birth in many countries, allowing doctors to start protective treatments before symptoms appear and helping families understand what to expect.

Introduction: Who Should Undergo Diagnostics and When

Sickle cell anaemia is often detected during pregnancy or soon after birth. In many countries, including the United States and the United Kingdom, screening for this condition is offered to all pregnant women to check if there’s a risk of a child being born with the disease. This early awareness helps families prepare and allows healthcare providers to plan appropriate care from the very beginning.^[5]

All babies born in the United States are now tested for sickle cell disease as part of routine newborn screening. This is typically done through the newborn blood spot test, also known as the heel prick test. Early diagnosis is critical because symptoms of sickle cell anaemia can begin when a baby is around six months old, and identifying the condition before symptoms appear allows doctors to start preventive treatments immediately.^[1][5]

Testing is not limited to newborns. Blood tests can be carried out at any age to check for sickle cell disease or to see if someone is a carrier of the gene that causes it. People with a family history of the condition, those from ethnic groups where sickle cell disease is more common, or individuals planning to have children may choose to undergo testing. African-Americans, Hispanic-Americans from Central and South America, and people of Middle Eastern, Asian, Indian, Mediterranean, or African descent are at higher risk and may benefit from screening.^[5][6]

If you or your partner carries the sickle cell gene, genetic counseling before pregnancy can help you understand the options and implications. Knowing your carrier status allows for informed family planning decisions and prepares you for potential outcomes.^[1]

Diagnostic Methods

The primary way to diagnose sickle cell anaemia is through a blood test. This test checks for the form of hemoglobin—the protein in red blood cells that carries oxygen—that underlies sickle cell anaemia. Hemoglobin S is the abnormal form that causes red blood cells to become rigid and shaped like a sickle or crescent moon instead of remaining round and flexible.^[9]

In newborns, the blood sample is usually collected from a finger or heel prick. In older children and adults, a blood sample is taken from a vein in the arm. The sample then goes to a laboratory where it is screened for the sickle cell form of hemoglobin. The test can identify not only sickle cell anaemia but also other forms of sickle cell disease and whether someone is a carrier of the sickle cell trait.^[9]

Once a diagnosis of sickle cell anaemia is confirmed, your healthcare professional might suggest additional tests to check for possible complications of the disease. These tests help doctors understand how the disease is affecting your body and allow them to plan treatments to prevent serious problems from developing.^[9]

Assessing Stroke Risk

Children with sickle cell anaemia have a higher risk of stroke, which can be life-threatening or cause lasting damage. A special ultrasound machine can reveal stroke risk in children by using sound waves to measure blood flow to the brain. This painless test, called transcranial Doppler ultrasonography, can be used in children as young as two years old. If the test shows that a child is at high risk for stroke, regular blood transfusions can be started to decrease that risk significantly.^[9]

Tests Before Birth

Sickle cell disease can be diagnosed in an unborn baby through prenatal testing. This involves sampling some of the amniotic fluid surrounding the baby in the womb or tissue from the placenta. If you or your partner has sickle cell anaemia or carries the sickle cell trait, your healthcare team can discuss this screening option with you. Knowing before birth allows families to prepare emotionally and practically for a child with sickle cell disease and ensures that medical care can begin immediately after delivery.^[9]

Carrier Testing and Genetic Counseling

People who carry one sickle cell gene and one normal gene have what is called sickle cell trait. They usually do not have symptoms of the disease and live normal lives. However, if both parents carry the trait, there is a one in four chance with each pregnancy that their child will be born with sickle cell anaemia. Carrier testing is a simple blood test that can determine if you carry the sickle cell gene. If you find out you are a carrier, you will likely be referred to a genetic counselor who can explain what this means for you and your family.^[1][3]

Distinguishing Sickle Cell Anaemia from Other Conditions

The blood test that identifies sickle cell anaemia can also distinguish it from other types of sickle cell disease. There are several forms of sickle cell disease depending on which genes a person inherits from their parents. The most common and usually most severe form is called HbSS, or sickle cell anaemia, where a person inherits two hemoglobin S genes, one from each parent. Other forms include HbSC and HbS beta thalassemia, which are usually milder. Knowing the exact type of sickle cell disease helps doctors predict how severe symptoms might be and plan appropriate treatment.^[3]

Once sickle cell anaemia is diagnosed, doctors will also perform baseline blood tests to understand the patient’s normal levels. These might include measuring red blood cell counts, hemoglobin levels, and other markers that indicate how well organs are functioning. Over time, regular monitoring through blood tests and other examinations helps track the disease’s impact and adjust treatments as needed.^[4]

Diagnostics for Clinical Trial Qualification

Clinical trials are research studies that test new treatments for sickle cell disease, including medications, procedures, and even potential cures. Participating in a clinical trial might give patients access to new medicines and treatment options that are not yet available to the general public. However, not everyone with sickle cell anaemia can join every clinical trial. Researchers use specific diagnostic tests to determine whether a patient qualifies for a particular study.^[2]

Qualification criteria vary depending on what the clinical trial is testing. Generally, participants must have a confirmed diagnosis of sickle cell disease through blood testing. The blood test must show the presence of hemoglobin S and identify the specific type of sickle cell disease the person has. Some trials may focus only on people with HbSS (sickle cell anaemia), while others might include people with HbSC or HbS beta thalassemia.^[3]

Beyond confirming the diagnosis, clinical trials often require additional baseline tests to assess a patient’s overall health and the severity of their disease. These tests help researchers understand how the disease is affecting the patient before any experimental treatment begins. They also help identify patients who are most likely to benefit from the treatment being tested and ensure that participation in the trial will be safe for the individual.

Common baseline tests for clinical trial qualification may include a complete blood count to measure red blood cells, white blood cells, and platelets. Hemoglobin levels are particularly important because they indicate the severity of anaemia. Researchers may also check for markers of organ damage, such as kidney function tests and liver function tests, because sickle cell disease can affect many organs over time.^[4]

Some clinical trials test treatments aimed at preventing specific complications, such as stroke or pain crises. For these studies, researchers might use transcranial Doppler ultrasound to assess stroke risk or require detailed records of how many pain crises a patient has experienced in the past year. Imaging tests like MRI scans, CT scans, or ultrasounds may be used to evaluate organ damage or look for signs of complications like lung problems or kidney disease.

Genetic testing may also be part of the qualification process for some trials, especially those testing gene therapies or treatments that target specific genetic mutations. Researchers need to confirm the exact genetic changes causing a patient’s sickle cell disease to ensure the experimental treatment will work for them.

Clinical trials may also require patients to be within a certain age range, have a certain level of disease severity, or have experienced specific complications. Some trials exclude patients who have had certain treatments in the past, such as a stem cell transplant, or who have other serious health conditions that could interfere with the study results.

If you or your child has sickle cell anaemia and you are interested in participating in a clinical trial, your hematologist can help you find studies that might be appropriate. The diagnostic tests you have already undergone as part of your regular care may be sufficient for some trials, while others may require additional testing. Your healthcare team will explain what tests are needed and what the trial involves so you can make an informed decision about whether to participate.^[2]