Sickle cell and thalassaemia screening: programme overview

Read an overview of the NHS sickle cell and thalassaemia screening programme (SCT), its services, and contact information.

Screening is the process of identifying people who appear healthy but may be at increased risk of a disease or condition.

Healthcare professionals will offer information, further tests and appropriate treatment to reduce their risk or any complications arising from the disease or condition.

The NHS Sickle Cell and Thalassaemia (SCT) screening programme is a genetic screening programme. This means that it also identifies people who are genetic carriers for sickle cell, thalassaemia and other haemoglobin disorders.

If 2 people who are carriers have a baby together, there is an increased risk that their baby could inherit a haemoglobin disorder.

The screening process is not perfect and in every programme there are a number of false positives and false negatives.

The SCT screening programme is one of the antenatal and newborn NHS population screening programmes.

It screens for:

It offers screening to:

Evidence and recommendations

The UK National Screening Committee (UK NSC) assesses evidence and makes recommendations to the 4 UK governments about population screening programmes.

Sickle cell disease

Sickle cell disease is the name for a group of related conditions which affect the quality of haemoglobin and the capacity to carry oxygen around the body.

The most serious form of the disease is sickle cell anaemia.

Other conditions that need treatment include Haemoglobin SC disease and S beta thalassaemia.

There are a number of haemoglobin conditions which have no symptoms or very mild symptoms. Healthcare professionals can refer individual to a specialist haemoglobinopathy counsellor to explain the significance of these conditions.


Thalassaemia is the name for a group of related conditions affecting the amount of haemoglobin that the body produces and its capacity to carry oxygen around the body.

Haemoglobin disorders

There are about 1000 different genes for unusual red blood cells. Most conditions arising from inheriting these genes are not of clinical significance.

The SCT programme does identify and report some of these genes. This is because a person who has a haemoglobin condition, or who carries an unusual gene, can pass on a clinically significant condition if they have a baby with another person in the same situation.

The type of condition that a baby can inherit depends on the exact genes for haemoglobin from both parents.

The laboratory handbook explains which genes to report.

Genetic carriers

People with haemoglobin disorders have inherited 2 unusual genes for haemoglobin: 1 from their mother and 1 from their father.

People who are carriers have inherited 1 unusual gene for haemoglobin from 1 parent. This is sometimes known as having sickle cell or thalassaemia trait. It usually causes no health issues.

Health professionals should make sure that carriers of the sickle cell (S) gene know they can have health problems in rare situations where there is a lack of oxygen.

These situations include having an anaesthetic and taking part in some extreme sports.

If a carrier has a baby with a partner who is also a carrier of an unusual gene for haemoglobin, the baby can inherit a haemoglobin condition.

The severity of the condition depends on the exact combination of genes that the baby inherits.

Where both partners know they are genetic carriers and wish to have a baby, they can consider the option of pre-implantation genetic diagnosis (PGD).

For PGD the couple undergoes in vitro fertilisation (IVF). The resulting embryos are screened. A maximum of two embryos which do not contain the genetic mutation are replaced in the uterus. Further information is available from Genetic Alliance UK.

Being a carrier for these conditions is more common in people whose families came from malarial regions of the world. This is because carrier status gives some protection against malaria in infancy. This genetic advantage means the conditions are more common in those areas.

Health professionals ask about family origins as part of antenatal screening. Ensure carriers know they should still take the normal precautions when travelling to malarial areas.

Recommendations and guidelines

The UK National Screening Committee (UK NSC) makes recommendations to ministers about all decisions regarding screening policy for the antenatal and newborn screening programmes.

The service specification sets out how the recommendations apply to every stage of the screening journey for SCT.

The laboratory handbook sets out how recommendations apply to laboratory processes, including which types of carrier to report.

DNA testing for transfused babies sets out the recommendations and processes for offering DNA tests to babies who have received a blood transfusion before newborn blood spot screening.

All SCT screening recommendations are evidence based.

Screening process

The SCT care pathway provides a visual representation of the process of antenatal and newborn screening with quick links to supporting information for each stage.

The screening tests for you and your baby leaflet explains the tests in antenatal and newborn screening.

SCT currently offers:

Testing before conception

The UK NSC has not recommended population screening before conception, but individuals may want to know their carrier status when planning to have a baby.

Advise individuals to request a test for carrier status from their general practitioner (GP) or a trained haemoglobinopathy counsellor.

Antenatal screening

Antenatal screening identifies expectant parents who are genetic carriers of an unusual form of haemoglobin.

In rare cases, screening will detect a woman with a haemoglobin condition that she did not know about. This enables healthcare professionals to make special arrangements for care during pregnancy.

If both parents are carriers there is a 1 in 4 chance that their baby will inherit a haemoglobin disorder.

Offer known carrier parents counselling and a diagnostic test for the fetus, known as prenatal diagnosis (PND).

If PND shows that the baby has inherited a disorder, offer parents further counselling with the option of termination of pregnancy if required.

Aim to offer the initial screening test by 10 weeks of pregnancy. This gives couples time to complete all the tests and have the option to choose an early termination.

NHS Choices provides information for patients about antenatal screening for sickle cell and thalassaemia.

Newborn screening

Sickle cell

The heel prick test detects babies with sickle cell disorders so they can receive prompt treatment.

This procedure also identifies babies who are genetic carriers for sickle cell and is part of the NHS Newborn Blood Spot screening programme.


The UK NSC does not recommend newborn screening for thalassaemia because the test is not sufficiently reliable and there is no immediate treatment for babies with thalassaemia.

However, the newborn blood spot test does detect the most serious form of thalassaemia, beta thalassaemia major. It does not detect babies who are thalassaemia carriers.

Risks and limitations of SCT screening

There are no significant risks associated with screening for sickle cell and thalassaemia.

Patients need to understand that the test identifies whether they carry a gene for a SCT condition. If they are a carrier, this will have implications for planning to have a baby.

Screened individuals will have to make their own decisions about informing partners and other family members about their carrier status.

It is possible that patient’s blood relatives could also be carriers. This may be important information for them if they are planning to have a baby.

Encourage parents of babies identified as carriers to explain the significance of the result as the child grows up.

Providing and commissioning screening

There are resources and guidelines to help commission and provide SCT screening.

These include:

  • programme standards
  • failsafe procedures
  • key performance indicators
  • incident management guidance
  • leaflets and resources to give to the public

The guidelines on handling patient information explain how to use and safeguard personal data in screening.

Education and training

Read about the education and training for healthcare professionals working in SCT screening.

This includes e-learning and other training resources.


NHS population screening helpdesk

PHE Screening
Floor 5
Wellington House
133-155 Waterloo Road


The helpdesk is not for media enquiries and does not have access to screening results. For queries about results, contact your GP or local screening service. Order screening leaflets at

Published 1 January 2013