ad. 6. Can NIPT (NEOBONA/HARMONY/NIFTY) replace the first trimester ultrasound scan?
The screening ultrasound test of the first trimester at 11 – 13+6 weeks of gestation is mainly focused on the exclusion of major anomalies of fetal anatomy. The anomalies are often unrelated with genetic syndromes, e.g. acrania, extensive defects in the area of: spine, brain, limbs, diaphragm, front side of a chest and abdominal cavity, majority of the forms of the single ventricle heart defect, more severe anomalies of the bladder. The ultrasound parameters assessment for the calculation of the risk of the Down syndrome and other syndromes is an independent, additional element of the examination.
- the risk of trisomies, i.e. the Down, Edwards’ and Patau syndromes
- the risk of some microdeletion syndromes, e.g. DiGeorge syndrome
- the risk of other chromosomal aberrations
- fetal gender
The sensitivity of the NIPT method for the Down syndrome is higher than the sensitivity of an ultrasound scan, however, it is not 100%. As far as we are concerned, one false positive NIFTY result has been registered in Poland so far. The baby was born with the Down syndrome.
We would like to emphasize that the latest discussions concerning NIPT examinations might create an erroneous impression that non-invasive screening tests of high sensitivity may replace an ultrasound examination of the first trimester. Considering all fetal anomalies, the Down syndrome constitutes ab. 10-15% of them, whereas fetal anatomy defects as many as 66%. The belief that NIPT tests are sufficient might delay the diagnosis of more frequent fetal anomalies.