Down Syndrome Screening

Screening tests estimate the chances of your baby having Down syndrome.

Down syndrome is the most common chromosomal abnormality to affect babies (1:700). Due to this condition, babies with Down syndrome will need extra care as they grow, in terms of their development and health.

What is involved with this screening?


You have an ultrasound scan and a blood test during your first trimester, when you are between 10 weeks and 13 weeks and 6 days. The blood test checks for certain hormone levels. We prefer to book the scan between 12 – 14 weeks and have blood tests done before coming for the scan.

Nuchal translucency (NT) scan

The NT scan measures the fluid under the skin at the back of your baby’s neck and visibility of nasal bone is also assessed, these can determine your chances of having a baby with Down syndrome.

This combined screening test identifies approximately 90% of babies with Down syndrome.  It won’t be able to identify for certain if your baby has Down syndrome, however it will indicate the level of risk which will assist you and your health professional to decide if further diagnostic tests should be carried out. Following the scan a doctor will counsel you on ultrasound findings and screening test results.


Achieving a definite result

If your screening test shows you have a high risk (greater than 1:300), then you will be offered further tests such as NIPT (advanced screening test) or diagnostic invasive tests e.g. CVS or Amniocentesis which will give you a close to definite result.

Diagnostic tests being invasive, do unfortunately carry a very slight risk of miscarriage, which is why screening tests are used first and why it is important to visit an ultrasound practice such as ours, where you have highly qualified staff to rely on, to fully understand what will be happening and to take the absolute best care of you and your baby.