NT
Pronunciation: en-tee
Also written as: NT — Nuchal Translucency
Nuchal translucency, ultrasound measurement of fluid collection behind fetal neck used in first-trimester screening for chromosomal abnormalities.
Full Definition
Nuchal translucency (NT) refers to the ultrasound measurement of subcutaneous fluid collection in the nuchal region (back of the neck) of the fetus, performed between 11-14 weeks of gestation. This measurement is a key component of first-trimester combined screening for chromosomal abnormalities, particularly Down syndrome, trisomy 18, and trisomy 13. Increased NT thickness is associated with higher risk of chromosomal abnormalities, cardiac defects, and other structural anomalies. The measurement must be obtained according to strict technical criteria and performed by certified sonographers. NT measurements are combined with maternal serum markers (PAPP-A and free beta-hCG) and maternal age to calculate individualized risk assessments.
Usage
Usage note: Do not confuse with nuchal fold measurement performed in second trimester.
In Context
- "NT measurement was 2.8mm at 12 weeks, falling within the normal range." — First trimester ultrasound
- "Increased NT of 4.2mm prompted discussion of invasive diagnostic testing options." — Genetic counseling session