What we offer differs fundamentally from the traditional nuchal translucency (NT) scan. The early fetal scan is an advanced systematic examination of all fetal structures, especially the brain and the heart. This method is very thorough and uses recent technological advancements of high-end ultrasound probes to produce high-resolution images. We check all the baby’s structures, even its tiny fingers. Ultimately, the early fetal scan aims to exclude as many fetal anomalies as possible and provide reassurance to the parents.
On the other hand, the nuchal translucency (NT) scan was developed nearly 30 years ago (1992), during the early days of ultrasound technology. Revolutionary at the time, the NT scan measures the amount of fluid in the back of the fetal neck. Increased NT is a nonspecific marker for chromosomal, genetic, cardiac, and structural problems; however, increased NT is also not an uncommon feature in a normal pregnancy. Conversely, most babies born with other anomalies may have normal readings of NT.
Currently, NT readings are being used by the NHS as a part of a combined screening to assess the chance for Down’s syndrome (T21), and for trisomy 18 and 12. The NT test can currently be done in any NHS Trust and is performed by specially trained sonographers, which have regular external audits.
Because of the importance of NT, we perform meticulous measurements of this marker during our early fetal scan; however, we do not use the NT thickness measurement to assess Down’s syndrome. Instead, we use the more recently developed (2011) NIPT, which has a superior detection rate and fewer false positive results compared to the NT quantitative measure.
We use a NT thickness measurement of 3.5 mm as a cut-off for further referral of the mother to her healthcare provider.