Test Directory

First trimester combined antenatal screening test for Down's Syndrome

Containers - Adult

BrownCapGelClotted.jpg
Brown Cap, Gel Clotted
Volume Range

2.0 ml

Additive per Container

None

Reference ranges

If the screening test shows that the chance of the baby having Down's Syndrome is higher than 1 in 150, this is classified as a 'higher chance result'.

Laboratory Site

WGH
Crewe Road South
Edinburgh
EH4 2XU
Telephone (Biochemistry): 0131 537 1910/1

How to request

A specific first trimester screening form is completed by the midwife and needs to accompany the blood sample. It is essential that the form is completed appropriately as the information provided is used to calculate the reported chance of Down's Syndrome.

Anticipated turnaround

3 days

General additional information

​We offer a NSD designated service, providing screening for the whole of Scotland.

This is a screening test for Down's Syndrome (trisomy 21) which is performed in the first trimester between 11 weeks + 2 days and 14 weeks + 1 day. The biochemical markers PAPP-A and free β-hCG are analysed and the information is combined with the measurement of nuchal translucency, which is determined from the dating ultrasound scan, to report the chance of the baby having Down's Syndrome.