The usefulness of volume NT software in measuring the fetal nasal bone at 11 to 13 + 6 weeks of gestation.

The objective of this study is to investigate the reproducibility of 3D ultrasound to measure the fetal nasal bone (NB) at first trimester.A group of singleton viable pregnancies attending the 11 to 13 + 6 weeks aneuploidy screening at the University of Bologna were prospectively selected. For each patient, fetal NB was measured by 2D ultrasound. Subsequently, a 3D ultrasound of the fetal head was acquired, and fetal NB was measured by offline analysis using the volume nuchal translucency software. The correlation between 2D and 3D ultrasounds and the reproducibility of fetal NB measurement at 3D ultrasound were assessed.Overall, 161 Caucasian women were included in the study. At 3D ultrasound, NB measurement showed an excellent intraobserver [Oper 1, intraclass correlation coefficient (ICC) = 0.98; Oper 2, ICC = 0.921] and interobserver agreement (rc = 0.92). The agreement between 2D and 3D measurements was moderate (rc = 0.77).A 3D ultrasound supported by the volume nuchal translucency software may provide reliable measurements of the fetal NB in the first trimester.