nuchal fold
Pronunciation: /ˈnuːkəl foʊld/
Fetal neck skin thickness measured by ultrasound in the second trimester to assess chromosomal abnormality risk.
Full Definition
The nuchal fold is the measurement of skin thickness at the back of the fetal neck, typically assessed during the second trimester ultrasound examination between 15-22 weeks of gestation. This measurement differs from first trimester nuchal translucency and is part of the genetic sonogram or level II ultrasound. A nuchal fold thickness greater than 6mm is considered abnormal and may indicate increased risk for Down syndrome. The measurement is taken in the transverse plane of the fetal head at the level of the cerebellum and cisterna magna.
Usage
Usage note: Not hyphenated as a compound noun; distinct from nuchal translucency which is first trimester.
In Context
- "The nuchal fold measured 4.2mm, which is within normal limits for gestational age." — Ultrasound report
- "Increased nuchal fold thickness prompted genetic counseling referral." — Maternal fetal medicine consultation