The UK NSC recommendation on Trisomy 18 and Trisomy 13 Syndromes

Recommendation Systematic population screening programme recommended
Last review completed January 2016
Next review due in 2018/19
Key downloads

Evidence to support continuation or cessation of existing screening programmes is reviewed regularly. Each programme has an active portfolio of research, evidence and audit to support continual improvement. Find out more about  T18 and T13 screening, as part of the fetal anomaly screening programme in England.

The UK NSC has recommended evaluating the introduction of non-invasive prenatal testing (NIPT) to Down's syndrome screening. This will include scientific, ethical and user input to better understand the impact on women, their partners and the screening programme around the offer of cfDNA or invasive testing following a screening test result where:


i. the screening test risk score for trisomy 21 (T21) is greater than or equal to 1 in 150

ii. the combined test risk score for trisomy 18 (T18) and trisomy 13 (T13) is greater than or equal to 1 in 150


Find general information about population health screening.

Why is screening recommended by UK NSC?

Following the review of cfDNA (also known as NIPT) screening in pregnancy, an evaluation was recommended into its introduction because:

  • an invasive diagnostic test carries a small risk of miscarriage. The evidence suggests that NIPT will reduce the number of women being offered an invasive test
  • however, while we know that the accuracy of NIPT is very good, we don’t yet know how it will perform in an NHS screening programme pathway
  • for women who choose to have NIPT, this will add in an extra step in the screening programme. The impact of this, and the choices women make at different points in the pathway, is something that we hope to gain a better understanding of through further research and evaluation

More about T18 and T13

Edwards' Syndrome (Trisomy 18) and Patau’s syndrome (Trisomy 13) are rare but very serious conditions which affect a small number of babies every year. They are caused (like Down’s syndrome) by the baby having an incorrect number of chromosomes in every cell. Chromosomes are structures that carry important information that determine how we develop.  

Most babies will sadly die before they are born or shortly after birth. Some babies may survive to adulthood but this is rare. Many of these babies will unfortunately be stillborn. If they survive it is difficult to say how serious the effects will be before the baby is born. However, all babies born with Edward’s Syndrome and Patau’s Syndrome will have a wide range of problems, which are usually extremely serious. These may include major brain abnormalities, heart problems, unusual head and facial features, growth problems, unable to stand or walk, unable to talk and problems with their kidneys.

Although women of any age can have a child with Edwards' or Patau’s syndrome, the chance increases as a woman gets older.

Edwards' syndrome affects about 3 of every 10,000 births and Patau’s about 2 of every 10,000 births.

When a woman is tested for Down’s syndrome in early pregnancy the ultrasound scan may also suggest that her baby has Edwards or Patau’s syndrome.

A number of questions and answers have been developed to help explain the current screening recommendations.

>>Read more about T18 on NHS Choices


Antenatal Results and Choices
British Heart Foundation
British Pregnancy Advice Service
Child Growth Foundation
Children's Heart Federation
Contact a Family
Down Syndrome Education International
Down Syndrome Research Foundation UK
Down's Heart Group
Down's Syndrome Association
Down's syndrome Medical Interest Group
Elfrida Society
Faculty of Public Health
Genetic Alliance UK
Little Hearts Matter
Marie Stopes International
Miscarriage Association
PHG Foundation
Restricted Growth Foundation
Royal College of General Practitioners
Royal College of Midwives
Royal College of Obstetricians and Gynaecologists
Royal College of Physicians
Royal College of Physicians and Surgeons of Glasgow
Royal College of Physicians of Edinburgh
SHINE Charity
Sickle Cell Society
Society and College of Radiographers
Tiny Tickers
Together for Short Lives
Wolfson Institute of Preventive Medicine

The stakeholder groups will be involved when the recommendation is next reviewed. If you think your organisation should be added, please contact us. More information for stakeholders can be found in appendix C of the UK NSC evidence review process.

Related documents

icon cfDNA screening in pregnancy consultation comments (PDF document, 1.50MB, 14/01/16)
icon cfDNA screening in pregnancy cover sheet (PDF document, 568KB, 15/01/16)
icon Frequently Asked Questions (PDF document, 167KB, 28/07/14)
icon T18 and T13 Review Summary and Consultation Responses (PDF document, 785KB, 28/07/14)

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