Guidance

Down’s syndrome, Edwards’ syndrome and Patau’s syndrome screening pathway requirements specification

Published 21 June 2021

Applies to England

This document provides an overview of Down’s syndrome (trisomy 21 or T21), Edwards’ syndrome (trisomy 18 or T18) and Patau’s syndrome (trisomy 13 or T13) screening by describing what should happen at each stage of the pathway. It should be read alongside other guidance for the NHS fetal anomaly screening programme (FASP), including:

• screening standards
• programme handbook

Please also read the general information relevant to all the NHS screening programme pathways.

Down’s syndrome, Edwards’ syndrome and Patau’s syndrome screening

The NHS offers screening to all pregnant women to assess the chance of their baby being born with T21, T18 and T13 in both singleton and twin pregnancies.

If a woman accepts the offer of screening, she attends a dating scan and will have a blood sample taken. There are 2 screening tests that can be performed, depending on the results of the scan. These tests are:

• the combined test, which screens for T21 and/or T18 and T13
• the quadruple test, which screens for T21 only

The combined test can be performed when the baby’s crown rump length (CRL) is between 45.0mm and 84.0mm. This is between 11⁺² and 14⁺¹ weeks. The nuchal translucency (NT) measurement is needed to calculate the chance result. The blood sample can be taken from 10 weeks.

If the NT cannot be measured, or the CRL measurement is greater than 84.0mm, the woman is offered the quadruple test. If accepted, this test can be performed when the baby’s head circumference (HC) is between 101.0mm and 172.0mm. This is between 14⁺² and 20⁺⁰ weeks. The blood sample can be taken from 14⁺² weeks.

Following a higher chance result women are offered the choice of no further testing, non-invasive prenatal testing (NIPT) or prenatal diagnosis (PND).

Find out more in the programme overview.

End-to-end pathway

The T21, 18 and T13 screening pathway consists of the following elements.

The dotted boxes and numbered labels show how the different parts of the pathway map to the generic headings used below.

An accessible text-only version of this pathway is also available.

1. Before screening test

These requirements relate to making sure that screening is offered to the correct people.

Providers must have systems in place to:

• identify the eligible population by recording all pregnant women booking for antenatal care
• make sure women receive verbal and digital information (see Screening tests for you and your baby (STFYAYB)) about T21, T18 and T13 screening during first contact or booking visit; this must be recorded
• make sure women who are unable to access the digital version of STFYAYB are given a physical copy
• make sure women are signposted to or given STFYAYB translations or STFYAYB easy guides as appropriate
• make sure all eligible pregnant women are offered screening for T21, T18 and T13
• provide a weekly failsafe process to track all women from offer of screening to the end of the screening pathway and have a recorded outcome
• make sure there is effective communication between maternity and ultrasound services, for example when interpreting services are needed
• encourage all healthcare professionals who are involved in the pathway to complete the Screening for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome e-learning resource every 24 months

Refer to the ‘Screening for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome’ section of the FASP handbook for additional details.

2. Screening test

These requirements relate to the processes of carrying out the screening test.

Coverage

Providers must have systems in place to return data for the:

• coverage standard FASP-S01: T21/T18/T13 screening (KPI FA3)

Carrying out the screening test

Providers must have systems in place to:

• make sure an interpreter is available as required
• make sure the ultrasound practitioner checks the woman’s understanding of why she is attending the ultrasound scan
• make sure a local pathway is in place for women who need more information at the point of screening
• make sure women are offered combined screening and know they can choose to have:
  • no screening
  • screening for T21, T18 and T13
  • screening for T21 only
  • screening for T18 and T13 only
  • make sure all healthcare professionals record the woman’s decision to accept or decline screening clearly and accurately in line with local guidelines
• make sure the ultrasound scan appointment incorporates:
  • pre-scan discussion
  • the ultrasound examination
  • post-scan information giving
  • recording scan results and actions appropriately
• perform the scan in accordance with the FASP handbook guidance for the combined and quadruple screening tests
• make sure complete and accurate request forms are received by the screening laboratory
• make sure women are also offered the 20-week screening scan (performed between 18⁺⁰ and 20⁺⁶ weeks of pregnancy)
• provide a weekly failsafe process to track the women, who have accepted screening, have completed both parts of the test (scan and blood sample)
• make sure there are weekly failsafe systems in place to track women who do not attend appointments
• make sure any ultrasound practitioner performing the NHS FASP screening or diagnostic ultrasound scans holds, as a minimum, the qualifications outlined in the FASP handbook
• make sure ultrasound practitioners are aware of:
  • Royal College of Radiologists (RCR) and Society and College of Radiographers (SCoR) standards for the provision of an ultrasound service
  • British Medical Ultrasound Society (BMUS) guidelines for the safe use of diagnostic ultrasound equipment
• make sure all ultrasound practitioners involved in the pathway complete the e-learning resource First trimester resource for ultrasound practitioners every 12 months
• make sure all ultrasound providers participate in the Down’s syndrome quality assurance support service (DQASS)
• make sure laboratories have systems in place to comply with the FASP handbook guidance for the combined and quadruple screening tests
• make sure laboratories participate in quality assurance schemes including:
  • United Kingdom Accreditation Service (UKAS)
  • National External Quality Assessment Service (NEQAS)
  • DQASS
• return data for the test standard FASP-S05: turnaround time and test standard FASP-S06: inadequate samples (KPI FA4)

Refer to the screening for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome section of the FASP handbook for additional details.

FASP will monitor the detection rates and screen positive rates of the combined and quadruple tests against performance thresholds set for the national programme.

Screening outcome and referral

Providers must have systems in place to:

• provide a weekly failsafe process to make sure all screening results, including lower chance results, are communicated to women and the outcome of the discussion recorded
• make sure women with a higher chance result following combined or quadruple screening are offered an appointment in ≤ 3 working days of the result being available to discuss the options of:
  • no further testing
  • NIPT
  • PND
• refer to local or tertiary-level centre, depending on the woman’s choice of the options above
• make sure all women with a higher chance NIPT result attend an appointment in ≤ 3 working days of maternity services receiving the result to discuss the options of:
  • no further testing
  • PND (PND should be completed in ≤ 3 working days of the woman receiving the NIPT result)
• make sure all women with a ‘no result’ NIPT result attend an appointment in ≤ 3 working days of maternity services receiving the result to discuss the options of:
  • one further NIPT test
  • no further testing
  • PND (PND should be completed in ≤ 3 working days of the woman receiving the NIPT result)
• make sure local and tertiary-level referrals are recorded
• return data for referral standard FASP-S07: time to intervention
• return data for the NIPT experimental metrics

3. After screening test (diagnosis)

These requirements relate to the process of following-up women with higher chance results who wish to have PND.

Providers must have systems in place to:

• make sure, for women who accept PND, a sample is received by the laboratory
• provide a failsafe process to make sure genomic laboratories know which samples to expect and follow up any missing samples with maternity services in a timely manner
• provide a weekly failsafe process to make sure each PND sample taken has a reported outcome
• refer women to appropriate services and support organisations in line with local guidelines

4. After screening test (intervention)

These requirements relate to the process of following-up people with a confirmed diagnosis and maximising the overall benefits from screening in terms of the final outcome to the person being screened.

Providers must have systems in place to:

• support women who choose to continue their pregnancy
• support and women who choose to end their pregnancy and refer to relevant support organisations
• report PND test results to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS)
• return data for the diagnosis/intervention standard FASP-S09: diagnostic tests

Pathway outcome

Providers must have systems in place to:

• show all women who choose to continue their pregnancy have been offered the 20-week screening scan
• offer follow-up support
• report pregnancy outcome to NCARDRS