Clinical utility of nuchal translucency screening

The term nuchal translucency (NT) is used to describe the accumulation of fluid behind the fetal neck visible on ultrasound in the first trimester of pregnancy. In singleton and dichorionic twin pregnancies, increased NT thickness is associated with trisomy 21 and other aneuploidies, major fetal anomalies (especially congenital heart disease), and genetic syndromes. The pathophysiology and significance of increased or discordant NT in monochorionic twin pregnancies is more complex and is associated with twin-to-twin transfusion syndrome and other pregnancy complications due to monochorionicity. The long-term neurological outcome of euploid children without structural anomalies after increased fetal NT seems to be favorable. Proper counseling is essential in the screening process. Special attention should be paid to the assessment of NT screening quality control. Even in the era of arising possibilities for noninvasive fetal karyotype determination from maternal blood, the role of NT screening is far from over. The association of this phenomenon with aneuploidies is only one of its utilities in modern obstetrics.