Increased Nuchal Translucency and Normal Karyotype

Abstract

The long-term neurodevelopmental outcome of karyotypically normal fetuses with increased nuchal translucency (NT) is unknown. A number of case reports have suggested a potential association between genetic syndromes and increased NT, but few studies have demonstrated a true association. This study was designed to assess the perinatal and pediatric outcomes among singleton fetuses with increased NT > the 99th percentile and normal karyotype up to 2 years of age. Antenatal work-up included first- and second-trimester anomaly scan, first- and second-trimester fetal echocardiography, and infection screening and genetic testing in selected cases. All surviving newborns were followed for up to 2 years of age. During the 4-year study period, 171 singleton fetuses with NT > 99th percentile and normal karyotype were identified. There were 7 (4.1%) cases of spontaneous fetal loss, 2 (1.2%) postnatal deaths, and 38 (22.2%) cases of terminations of pregnancy. Among the 124 survivors (72.5% of the cohort), 12 (9.7%) were born with structural defects. Among the 108 survivors followed up, moderate-to-severe neurodevelopmental impairment was diagnosed in 4 (3.7%) of the infants, all of whom were structurally normal. Overall, 50 fetuses/newborns had abnormalities, either structural defects or genetic syndromes. Prenatal diagnosis was achieved in 31 (83.8%) of the structural abnormalities and 9 (69.2%) of the genetic syndromes. A single umbilical artery was detected in 6 fetuses without fetal defects; 5 of these resulted in normal newborns (4.5%), and 1 was diagnosed with the 22q11 microdeletion syndrome at 2 years of age. These findings show that karyotypically normal fetuses presenting with NT above the 99th percentile had a 63% intact survival. The data show no apparent differences in long-term neurodevelopmental outcome between survivors and cohorts from the general population.