"When is the Best Time to Take the NT Test?"

NT Examination for Fetal Down Syndrome

The NT examination is a method used to assess whether a fetus is affected by Down syndrome. It is generally recommended to be performed between the 11th and 13th week of pregnancy, plus 6 days, which approximately corresponds to the 3rd month of pregnancy. Details are as follows:

The NT examination involves an ultrasound measurement of the thickness of the nuchal translucency (NT) at the back of the fetus's neck. The optimal timing for this examination is between the 11th and 13th week of pregnancy, plus 6 days. As pregnancy is commonly calculated in 4-week months, this translates to approximately the 3rd month of pregnancy, when the NT examination is most advisable.

Performing the NT examination too early may result in an incomplete development of the fetal nuchal translucency. Conversely, conducting it too late may see the nuchal translucency gradually absorb. Therefore, around the 11th to 13th week plus 6 days of pregnancy is considered the optimal time for the NT examination.

If a significant abnormality is detected in the NT examination, it may indicate congenital growth and developmental abnormalities in the fetus. Further diagnostic evaluations, such as Down syndrome screening, non-invasive DNA testing, 4D ultrasound examination, and amniocentesis, are necessary to confirm the diagnosis. If a severe congenital growth and developmental abnormality is confirmed, prompt termination of the pregnancy may be necessary to prevent the birth of a malformed child.