Increased nuchal translucency can be ascertained using transverse planes

Abstract

The detection of increased nuchal translucency is crucial for the assessment risk of aneuploidies and other fetal anomalies. This study aimed to investigate the ability of a transverse view of the fetal head to detect increased fetal nuchal translucency at 11 to 13 weeks of gestation. This was a prospective study enrolling a nonconsecutive series of women who attended our outpatient clinic from January 2020 to April 2021 for combined screening and were examined by operators certified by the Fetal Medicine Foundation. In each patient, nuchal translucency measurements were obtained both from a median sagittal view and from a transverse view. A second sonologist blinded to the results of the first examination obtained another measurement to assess intermethod and interobsever reproducibility. A total of 1023 women were enrolled. An excellent correlation was found between sagittal and transverse nuchal translucency measurements, with a mean difference of 0.01 mm (95% confidence interval,-0.01 to 0.02). No systematic difference was found between the 2 techniques. The inter-rater reliability (intraclass correlation coefficient, 0.957; 95% confidence interval, 0.892-0.983) and intrarater reliability (intraclass correlation coefficient, 0.976; 95% confidence interval, 0.941-0.990) of axial measurements were almost perfect. Transverse measurements of 3.0 mm identified all cases with sagittal measurements of ≥3.0 with a specificity of 99.7%; transverse measurements of >3.2 mm identified all cases with sagittal measurements of 3.5 mm with a specificity of 99.7%. The time required to obtain transverse nuchal translucency measurements was considerably shorter than for sagittal measurements, particularly when the fetus had an unfavorable position. When the sonogram is performed by an expert sonologist, the difference in nuchal translucency measurement obtained with a transverse or sagittal plane is minimal. Increased nuchal translucency can be reliably identified by using transverse views, and in some cases, this may technically be advantageous.