Nuchal translucency scan
(12 week ultrasound)

The nuchal translucency test is often called the 12 week ultrasound, although it can be performed between 11-14 weeks.


It’s a screening test that tells couples the risk of their baby having one of three major chromosomal abnormalities (Down syndrome, Edwards syndrome or Patau syndrome).


The nuchal translucency test combines a blood test, special ultrasound scan and the mother’s age to calculate the baby’s risk.


The blood test measures pregnancy proteins including hCG and PAPP-A, which are often abnormal in pregnancies affected by chromosomal problems. It takes 24-48 hours to process – ideally you should have the blood test 2 days before the scan, so that the results are available on the day.


During the ultrasound scan we measure the nuchal translucency, which is a little pocket of fluid behind the baby’s neck. We also look for baby’s nasal bone. Accurate ultrasound measurement is crucial and should be undertaken by a Fetal Medicine specialist or sonographer who is certified to perform NT scanning. (I am
certified by the Fetal Medicine Foundation and have performed thousands of NT scans over the years).


Overall, nuchal translucency screening detects approximately 95% of cases of Down syndrome. It misses 1-in-20 cases (a higher number than are missed on NIPT). Because it involves a detailed ultrasound scan, it can also detect early problems with the baby’s anatomy. It is non-invasive, so it carries no risk to the baby, and can be offered in twin and triplet pregnancies.


One small disadvantage is that nuchal translucency does not tell you the baby’s gender (but this can be checked at the 18-20 week fetal anatomy scan).

We offer the full range of specialist pregnancy scans. Please click on the links below for more information :

Nuchal ultrasound 12 weeks