The NT Down screening tests are both low risk, but the NF value is a little higher, the fetus may be at risk of chromosomal abnormalities and further testing is needed.
NT is generally an early pregnancy nuchal translucency thickness test, while NF is a mid-pregnancy nuchal skin fold thickness test, both are also the fetal chromosomal abnormalities of the test, one of the values of the abnormality, means that the fetus has the possibility of chromosomal malformations.
If the NT value is less than 2.5mm, the thickness of the nuchal translucency is normal. If the NF value is less than 6mm, the fetus may be at risk for chromosomal abnormalities, and further prenatal diagnostic testing is recommended, even if the Down’s syndrome is low risk.
Both are about fetal chromosomal abnormality test, only the detection time is different, one of the two appear too high is to be further examination.