Increased nuchal translucency in fetuses with a normal karyotype—diagnosis and management: An observational study
The use of nuchal translucency (NT) in 1992 by Nicolaides et al was a major breakthrough in screening for chromosomal aneuploidies at the end of the first trimester. However, pathological conditions other than chromosomal aneuploidies are also associated with increased NT, which can also be detected in normal fetuses. This study sought to evaluate the causes of this ultrasound sign in a group of patients from Iasi, Romania.
During the decade-long study period, there were 71 certified cases involving increased NT; the patients in these cases underwent diagnostic amniocentesis and karyotyping.
In most of the examined cases (55 cases, 78%), there was no aneuploidy. The remaining cases involved trisomy 21 (T21) (18%), trisomy 18 (T18) (2%), or triploidy (2%). In most cases, the indication for amniocentesis was increased NT alone (81%), whereas the remaining cases also involved advanced maternal age (5.5%), abnormal serologic markers (10%), or other ultrasound signs (3.5%) (2 cases—cardiac anomalies and fetal hydrops). A favorable pregnancy outcome at term was achieved in 40 cases (56% from total, 72% from euploid pregnancies); kidney anomalies or nonlethal cardiac conditions were observed in 12 cases (17%), 6 of which involved complications associated with premature onset of labor, and miscarriages occurred in 6 cases. Three cases were lost at follow-up.
Although it is common practice to assume that increased NT is an indication for amniocentesis, both literature results and our study findings indicate that the majority of cases with increased NT involve no aneuploidy and result in a favorable outcome if no other anomaly is present. Better evidence-based management of such cases could be promoted by conducting larger, multicenter studies, and following cases for longer periods.