Specification of screening pathways requirements for Down syndrome, Edwards syndrome and Patau syndrome

This document provides an overview of Down syndrome (trisomy 21 or T21), Edwards syndrome (trisomy 18 or
T18) and Patau syndrome (trisomy 13 or T13) screening by describing what needs to happen at each stage of the journey. It should be read in conjunction with other publications from Public Health England (EPS) advice for the NHS fetal abnormalities screening program (FASP), comprising:

Screening for Down’s Syndrome, Edwards Syndrome and Patau Syndrome

The NHS offers screening to all pregnant women to assess the chances of their baby being born with T21, T18 and T13 in single-fetal and twin pregnancies.

If a woman accepts the offer of testing, she goes to a dating scanner 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 seeks T21 and or T18 and T13
  • the quadruple test, which seeks T21 alone

The combined test can be performed when the length of the baby’s croup (Certificate revocation list) is between 45.0 mm and 84.0 mm. It is between 11+2 and 14+1 weeks. Nuchal translucency (NT) is needed to calculate the random result. The blood sample can be taken from 10 weeks.

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

As a result of a more likely result, women have the option of no other test, a non-invasive prenatal test (DPNI) or prenatal diagnosis (PND).

Find out more in the program overview.

End-to-end journey

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

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

A text-only version of this trail is also available.

1. Before the screening test

These requirements are intended to ensure that testing is available to the right people.

Suppliers must have systems in place for:

  • identify the eligible population by registering all pregnant women seeking antenatal care
  • ensure that women receive verbal and digital information about T21, T18 and T13 screening during the first contact or during the reservation visit; this must be recorded
  • make sure that women who cannot access the digital version of the screening tests for you and your baby (STFYAYB) receive a physical copy
  • make sure women are reported or STFYAYB translations or STFYAYB easy guides as appropriate
  • ensure that all eligible pregnant women are offered screening T21, T18 and T13
  • provide a seamless weekly process to follow all women from the screening offer to the end of the screening journey and have a recorded result
  • ensure that there is effective communication between maternity and ultrasound services, for example when interpretation services are required
  • encourage all healthcare professionals involved in the journey to complete the online learning resource “Screening for Down syndrome, Edwards syndrome and Patau syndrome” every 24 months

Refer to the “Screening for Down Syndrome, Edwards Syndrome and Patau Syndrome” section of the FASP manual for details.

2. Screening test

These requirements relate to the processes for performing the screening test.

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Suppliers must have systems in place to return data for:

Carrying out the screening test

Suppliers must have systems in place for:

  • ensure that an interpreter is available if needed
  • make sure the ultrasound practitioner checks to see if the woman understands why she is showing up for the ultrasound
  • ensure that a local pathway is in place for women who need more information at the time of screening
  • make sure women are offered combination screening and know they can choose to have:
    • no screening
    • screening for T21, T18 and T13
    • screening for T21 alone
    • screening for T18 and T13 alone
    • ensure that all healthcare professionals clearly and accurately document a woman’s decision to accept or decline testing according to local guidelines
  • make sure the ultrasound appointment includes:
    • pre-scan chat
    • ultrasound examination
    • post-scan information giving
    • record analysis results and actions appropriately
  • perform the scan in accordance with FASP guidance manual for combination and quadruple screening tests
  • ensure that complete and accurate application forms are received by the screening laboratory
  • ensure that women are also offered the screening examination at 20 weeks (carried out between 18+0 and 20+6 weeks pregnant)
  • provide a seamless weekly process to track women who have accepted screening, completed both parts of the test (scan and blood sample)
  • ensure that there are weekly fail-safe systems to track women who do not show up for appointments
  • make sure that any ultrasound practitioner performing the NHS FASP screening or diagnostic ultrasounds hold, at a minimum, the qualifications described in the FASP manual
  • make sure ultrasound practitioners are aware of:
  • ensure that all ultrasound practitioners involved in the journey complete the “First Trimester Resource for Ultrasound Practitioners” e-learning resource every 12 months
  • ensure that all ultrasound providers participate in the trisomy 21 quality assurance support service (DQASS)
  • ensure that laboratories have systems in place to comply with FASP guidance manual for combination and quadruple screening tests
  • ensure that laboratories participate in quality assurance programs, including:
  • return data for test standard FASP-S05: lead time and test standard FASP-S06: inadequate samples (KPI FA4)

Refer to the Screening for Down syndrome, Edwards syndrome and Patau syndrome section of the FASP manual for details.

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

Screening result and referral

Suppliers must have systems in place for:

  • provide a weekly safety process to ensure that all screening results, including low probability results, are communicated to women and that the outcome of the discussion is recorded
  • ensure that women with a higher likelihood of a result after combined or quadruple screening are offered an appointment within ≤ 3 working days of the result being available to discuss the following options:
    • no further tests
    • DPNI
    • PND
  • refer to local or tertiary level center, depending on the woman’s choice among the above options
  • make sure all women with higher chance DPNI result attend an appointment within ≤ 3 working days of maternity services receiving the result to discuss options for:
    • no further tests
    • PND (PND must be completed within ≤ 3 working days after the woman receives the DPNI results)
  • make sure all women with a “no result” DPNI result attend an appointment within ≤ 3 working days of maternity services receiving the result to discuss options for:
    • another DPNI test
    • no further tests
    • PND (PND must be completed within ≤ 3 working days after the woman receives the DPNI results)
  • ensure that local and tertiary references are recorded
  • return the data for the referenced standard FASP-S07: response time
  • return data for the DPNI experimental metrics

3. After screening test (diagnostic)

These requirements relate to the process of monitoring women with more likely outcomes who wish to have PND.

Suppliers must have systems in place for:

  • be sure, for women who accept PND, a sample is received by the laboratory
  • provide a security process to ensure genomics labs know what samples to expect and follow up on missing samples with maternity services in a timely manner
  • provide a weekly security process to ensure that each PND the sample taken has a reported result
  • refer women to appropriate services and support organizations according to local guidelines

4. After screening test (intervention)

These requirements relate to the process of following up those with a confirmed diagnosis and maximizing the overall benefits of screening in terms of the end result for the person being screened.

Suppliers must have systems in place for:

Result of the process

Suppliers must have systems in place for:

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

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