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  6. Screening for Down’s Syndrome, Edwards’ syndrome, and Patau’s syndrome with a Vanished Twin (349)
Please update your RDS mobile app to version 4.7.1

We are pleased to advise that deep linking capability, enabling users to directly download individual mobile toolkits, has now been released on the RDS mobile app. When you install the update, you will see that each toolkit has a small QR code icon the header area beside the search icon – see screenshot below. Clicking on this icon will open up a window with a full-size QR code and the alternative of a short URL for sharing with users. Instructions are provided.

You may need to actively install the update to install RDS app version 4.7.1 to see this improvement. Installing this update is also strongly recommended to get the full benefits of the new contingency arrangements – specifically, that if the RDS website should fail, you will still be able to download new mobile app toolkits. 

To check your current RDS version, click on the three dots bottom right of the RDS app screen. This takes you to a “More” page where you will see the version number.  To install latest updates:

On iPhones – go to the Apple store, click on your profile icon top right, scroll down to see the apps waiting to be updated and update the RDS app.

On Android phones – these can vary, but try going to the Google Play store, click on your profile icon top right, click on “Manage apps and device”, select and update the RDS app.

Please get in touch with ann.wales3@nhs.scot with any questions.

Screening for Down’s Syndrome, Edwards’ syndrome, and Patau’s syndrome with a Vanished Twin (349)

Please report any inaccuracies or issues with this guideline using our online form

The definition of a vanished twin is when one fetus in a twin pregnancy is non-viable. It may be partially or completely reabsorbed.

An ultrasound scan for the combined or quadruple test* may show either:

  • An empty second pregnancy sac
  • A second pregnancy sac containing a nonviable fetus

Empty second pregnancy sac and the combined test

When there is an empty second pregnancy sac, the combined test can be used to calculate the chance result

Second pregnancy sac containing a non-viable fetus and the combined test

When there is a second pregnancy sac containing a non-viable fetus, the combined test should not be used to calculate the chance result.

The quadruple test can be offered.

The quadruple test

The quadruple test can be offered to a woman with a vanished twin pregnancy

 

*The combined test assesses the chance of the baby having trisomy 21 (T21), trisomy 18 (T18) and trisomy 13 (T13) by using;

  • Maternal age
  • Biochemical markers free beta human chorionic gonadotrophin (bhCG) and pregnancy associated plasma protein-A (PAPP-A)
  • Ultrasound measurements- nuchal translucency (NT) and crown rump length (CRL)

The quadruple test screens for T21 only

The quadruple test uses maternal age and the following 4 biochemical markers measured from 14+2 to 20+0 weeks:

  • Alpha-fetoprotein (AFP)
  • Human chorionic gonadotrophin (hCG)
  • Inhibin-A
  • Unconjugated oestriol (uE3)

Editorial Information

Last reviewed: 23/10/2024

Next review date: 24/10/2027

Author(s): Dawn Kernaghan .

Version: 3

Approved By: Maternity Clinical Governance Group

Document Id: 349