This scan is performed from 11 weeks to 13 weeks 6 days.
A properly done NT scan is helpful as each woman will be given an estimate of her individual chance of having chromosomal abnormalities for this pregnancy. This is calculated by taking into account the age of the mother, measurement of two hormones in the mother’s blood, and the scan findings of nuchal translucency thickness, nasal bone, blood flow through the fetal heart, and ductus venosus and fetal abnormalities. Parents will receive full counseling concerning the significance of these changes and the various options for further investigations including invasive testing or Non-invasive prenatal screening.
- Early screening for Chromosomal and genetic abnormalities (NT scan+ biochemistry has a detection rate as high as 90-95%).
- Diagnosing major fetal structural abnormalities (60% of all lethal abnormalities). Some major abnormalities may be visible at this gestation. However it will still be necessary to have a 20 week anomaly scan.
- Screening for Maternal pre-eclampsia and Fetal growth restriction by combining a priori risk from maternal characteristics and medical history with the results of various combinations of biophysical and biochemical measurements
- To diagnose early miscariage. Unfortunately, in 2% of women who attend for a nuchal scan it is found that the fetus has died, often several weeks before and without any warning. Couples will receive full counseling as to the possible causes of this problem and the options for subsequent measures that may be necessary.