nuchal translucency
Pronunciation: NEW-kul trans-LOO-sen-see
An ultrasound measurement of fluid collection behind the fetal neck used for Down syndrome screening in the first trimester.
Full Definition
Nuchal translucency (NT) is a sonographic measurement of the subcutaneous fluid collection behind the fetal neck, typically performed between 11 weeks 0 days and 13 weeks 6 days of gestation. The measurement is obtained in a midsagittal view and must meet strict technical criteria for accuracy. Increased nuchal translucency thickness (typically >3.5mm) is associated with increased risk of chromosomal abnormalities, particularly trisomy 21, 18, and 13, as well as certain cardiac defects. The NT measurement is combined with maternal serum biochemistry and maternal age to calculate risk as part of first-trimester screening programs.
Usage
Usage note: Often abbreviated as NT in clinical notes. Always express measurement in millimeters.
In Context
- "The nuchal translucency measurement of 4.2mm prompted genetic counseling referral." — First trimester screening report
- "Normal nuchal translucency of 1.8mm was documented at 12 weeks gestation." — Ultrasound report