The aim of this study was to examine the prevalence of major and minor anomalies according to the increase of NT thickness.

This is a long-term retrospective study in which singleton gestations of euploid fetuses with increased NT were analyzed. NT measurement was performed in the first trimester examination according to the criteria of fetal medicine foundation (FMF) when the fetal crown-rump length (CRL) was 45 to 84 mm. The cases were followed up from 1 to 5 years postpartum to assess the presence of CHD and to point out other anomalies that could be associated with increased NT.

The outcome of 133 cases could be analysed out of 198 pregnancies of which in 55 cases some congenital anomalies (minor or major) were revealed up to the 5 years of life (prevalence of 41.4%). The prevalence of CHDs, including the defects of the great vessels, stood out among the others. In the group with NT between 95th and 99th centiles four cases with minor heart problems were identified (11.1%, 4/36). The rate of major cardiac defects proved to be 13.3% (6/45) in the group with NT between 3.5-4.4 mm, and 17.3% (9/52) in the group with NT > 4.5 mm. Among the 35 healthy children with various minor health problems not related to the presence of increased nuchal translucency there were 7 cases with hydrocele. In 3 of them it was associated with unilateral inguinal hernia but in 3 it was isolated and one was part of a complex malformation (The rate of other organ-specific anomalies did not prove to be significant). In the whole study population only thirteen cases (9.8%) ended up in intrauterine death, or arteficial abortion.

The prevalence of major cardiac defects as well as other major anomalies increases with fetal nuchal thickness. Since the prevalence of CHD is 100 times higher in the population of fetuses with NT above 4.5 mm, specialist fetal echocardiography should be offered in the second trimester together with other follow-up investigations. Among the children without any major abnormalities, a high number of minor anomalies were revealed during the long-term follow-up. These anomalies do not have significant disadvantage to the quality of life, but some of them necessitates short or long-term medical treatment and this should also be leveled with the future parents. Despite the numerous investigations the exact etiology of increased NT remains unknown. The relatively high prevalence of hydrocele in the newborns in our material raises the question wheather it is related to the presence of NT in the fetal period because of abnormal lymphatic development or alterations in the extracellular matrix. Further long-term follow-up studies could probably contribute to find explanation on the etiology of increased NT in the first trimester. These data can be used when counseling parents of euploid fetuses with increased fetal NT.