NT normal value

NT refers to the nuchal translucency thickness—the measurement of the fluid-filled space at the back of the fetal neck. During early pregnancy, certain metabolic processes in the fetus may lead to the formation of a thin, fluid-filled, transparent layer in this region. By measuring the thickness of this layer via ultrasound, clinicians can perform an initial assessment for potential metabolic abnormalities.

Normal NT Values

The normal NT value is generally less than 2.6 mm. NT screening is typically performed between 12 and 14 weeks of gestation and helps assess the risk of chromosomal abnormalities—including Down syndrome (trisomy 21). Chromosomal abnormalities are often associated with increased NT thickness. NT measurement requires high-resolution ultrasound equipment and highly skilled sonographers; therefore, it is usually available only at well-equipped hospitals. An NT measurement <2.6 mm is considered normal, and routine follow-up examinations are recommended. If the NT measurement exceeds 2.6 mm, maternal serum screening for Down syndrome should be performed during the second trimester.

NT screening is a prenatal test used to estimate the risk of fetal Down syndrome. It is typically performed between 10 and 14 weeks of gestation, with the optimal timing being at 12 weeks and 5 days. If the gestational age is too early, the NT may not be clearly visualized; if too late, the subcutaneous fluid may be absorbed by developing lymphatic tissue.

We hope this article has been helpful to you!