Down’s syndrome, Edwards’ syndrome and Patau’s syndrome screening pathway
Updated 19 May 2021
© Crown copyright 2021
This publication is licensed under the terms of the Open Government Licence v3.0 except where otherwise stated. To view this licence, visit nationalarchives.gov.uk/doc/open-government-licence/version/3 or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email: psi@nationalarchives.gov.uk.
Where we have identified any third party copyright information you will need to obtain permission from the copyright holders concerned.
This publication is available at https://www.gov.uk/government/publications/fetal-anomaly-screening-care-pathways/downs-syndrome-edwards-syndrome-and-pataus-syndrome-screening-pathway-combined-or-quadruple-test-taken-on-or-after-1-june-2021
This flowchart (text description and illustration below) describes the screening pathway for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome including non-invasive prenatal testing (NIPT).
1. Offer information and screening for T21, T18 and T13
Offer the pregnant woman screening for Down’s syndrome (trisomy 21), Edwards’ syndrome (trisomy 18) and Patau’s syndrome (trisomy 13) and information about the screening test(s).
Before screening is carried out, the baby’s crown rump length (CRL) is measured at the dating scan.
2. Does the woman accept screening?
Yes: The woman accepts screening for:
- Down’s syndrome, Edwards’ syndrome and Patau’s syndrome
- Edwards’ syndrome and Patau’s syndrome
- Downs’ syndrome only
Go to question 3.
No: Offer 20-week screening scan. End of pathway.
3. Is the baby’s CRL less than 45.0mm?
Yes: Recall the woman for a repeat scan when CRL measures 45.0mm or more. Then go to question 4.
No: Go to question 4.
4. Is the baby’s CRL between 45.0mm and 84.0mm?
Yes: Carry out combined screening test for chosen conditions. Go to question 7.
No: Go to question 5.
Please note: if it is not possible to measure the baby’s nuchal translucency (NT) despite 2 attempts (‘twice on the couch’), further attempts do not need to be offered. The woman should be offered quadruple screening.
5. Is the baby’s head circumference (HC) between 101.0mm and 172.0mm
Yes: Offer T21 quadruple screening (Down’s syndrome only). Go to question 6.
No: Offer 20-week screening scan. End of pathway.
6. Does the woman accept quadruple screening?
Yes: Carry out quadruple test. Go to question 7.
No: Offer 20-week screening scan. End of pathway.
7. Is the result lower chance?
Yes: Offer 20-week screening scan. End of pathway.
No: Refer for discussion of further choices. Go to question 8.
8. Does the woman want further tests?
Yes: Go to question 9.
No: Offer 20-week screening scan. End of pathway.
9. Which test does the woman want?
NIPT: Carry out NIPT. Go to question 10.
CVS or amniocentesis: Carry out CVS or amniocentesis test. Go to question 12.
10. What is the result of NIPT?
Lower chance result: Offer 20-week screening scan. End of pathway.
Higher chance result: Discuss options. Go to question 11.
11. Does the woman want further tests?
Yes: Carry out CVS or amniocentesis test. Go to question 12.
No: Offer 20-week screening scan and follow-up support. End of pathway.
12. Does baby have Down’s syndrome, Edwards’ syndrome or Patau’s syndrome?
Yes: Discuss options with the woman. Go to question 13.
No: Offer 20-week screening scan. End of pathway.
13. What is the woman’s choice?
Continue pregnancy: Offer 20-week screening scan and follow-up support. End of pathway.
Terminate pregnancy: Offer follow-up support.