NT scan and blood test
(11 weeks – 13 weeks)
Although the vast majority of babies have no problems at all, very occasionally, a baby will develop an abnormality. The Nuchal Translucency (NT) scan and blood test are designed to identify some of the more common fetal abnormalities.
The commonest genetic abnormality is Down’s Syndrome, which occurs in approximately 1 in 600 pregnancies. Although Down’s Syndrome is more common in older mothers, it can occur in any pregnancy, regardless of the mother’s age.
With Down’s Syndrome, the developing baby has an additional chromosome - chromosome 21 - in each cell, which causes a wide spectrum of disability (more details can be found at www.downs-syndrome.org.uk).
Following the discovery of a link between increased nuchal translucency at 11-13 weeks and Down’s syndrome, the latest research suggests that the optimum screening test for Down’s Syndrome during the first trimester is provided by a combination of:
- the age of the mother
- the amount of fluid behind your baby’s neck (nuchal translucency)
- the presence or absence of your baby’s nasal bone
- the presence or absence of any physical abnormalities
- the level of two hormones in the mother’s, blood - ß·hCG & PAPP·A
The NT scan and blood test incorporates the ultrasound findings – which provide information about the amount of fluid behind your baby’s neck - and the results of a simple blood test. The results are available within five working days and you will be contacted so Dr Calderwood can discuss the results with you.
Screening for other chromosomal abnormalities
The NT scan and blood test are also indicators of other, much rarer, chromosome abnormalities, including Edward's Syndrome (Trisomy 18) and Patau's Syndrome (Trisomy 13) and these results will also be discussed with you and included in your report.
These syndromes are similar to Down’s Syndrome in that each cell has an extra chromosome (an extra chromosome 18 in the case of Edward's Syndrome and an extra chromosome 13 in the case of Patau's Syndrome). Both of these conditions are very serious and babies with either of these syndromes die before they are born or very shortly afterwards.