Elevated nuchal translucency, is it time to discuss the cut off?

Area of Science:

• Maternal-Fetal Medicine
• Prenatal Diagnostics
• Genetics

Background:

• Nuchal translucency (NT) measurement is a key first-trimester screening tool.
• Identifying fetuses with increased NT requires further investigation for optimal outcomes.

Purpose of the Study:

• To assess pregnancy and postnatal outcomes in fetuses with NT between the 95th and 99th percentile.
• To determine if these fetuses warrant advanced investigations beyond routine scans.

Main Methods:

• A multicenter retrospective observational study analyzed cases with NT between the 95th and 99th percentile (Jan 2015-Dec 2020).
• Unfavorable outcomes included miscarriage, intrauterine fetal death (IUFD), chromosomal/genetic abnormalities, major malformations, and neurodevelopmental delay.
• Outcomes were compared to the general population.

Main Results:

• An unfavorable outcome rate of 25.44% was observed.
• Significantly higher incidences of chromosomal abnormalities/genetic syndromes (OR 6.99) and major malformations (OR 17.77) were found.
• Neurodevelopmental delay incidence was not significantly increased (OR 0.64).

Conclusions:

• Fetuses with NT in the 95th-99th percentile range exhibit elevated risks for adverse pregnancy and postnatal outcomes.
• A lower NT threshold (NT > 95th percentile) may justify further investigations like detailed ultrasound, fetal echocardiography, and genetic counseling.
• Consideration of fetal karyotype and chromosomal microarray analysis (CGH array) is recommended for these cases.