Increased nuchal translucency: predictive capacity for chromosomopathies

Abstract

Introduction: Nucal translucency is a echographic marker for chromosome abnormalities in the first trimester of gestation. Increased NT is primarily associated with chromosomal abnormalities, particularly trisomy 21 in 50%. It is linked to an adverse perinatal and neonatal prognosis, although there exists a percentage of normal fetuses despite an elevated NT. Objective: To correlate karyotype results in samples of amniotic fluid (AF) and chorionic villus biopsy (CVB) in patients with increased NT during ultrasound screening. Method: This was an analytical, retrospective, Type III cohort study, involving a population of a total of 5,969 patients who underwent cytogenetic studies between the years 2011-2022. Results indicating increased NT were reviewed, yielding 141 results. The sample consisted of 52 AF samples where the thickness of NT was reported, and 30 CVB results that met the inclusion criteria. Results: Fetal karyotype was reported as normal in 46.30% and abnormal in 57.70% of AF samples. In CVB, 60% were reported as normal and 40% as abnormal. Trisomy 21 was the most common chromosomal abnormality in both types of studies, followed by Monosomy X, Trisomy 18, and Trisomy 13. Monosomy X presented the thickest NT in the AF group, while Trisomy 21 predominated in the CVB group. Conclusion: The increase in fetal nuchal translucency thickness between weeks 11 and 14 is a common phenotypic expression of chromosomal abnormalities and malformations. However, it can also be elevated in euploid fetuses with normal postnatal development.