Measurement of nuchal volume in the first trimester Down screening using three-dimensional ultrasound.

OBJECTIVES

Screening of fetuses at 11 to 14 weeks of gestation for Down syndrome using stored volumes acquired by a three-dimensional (3D) scanner.

METHOD

Thirty-four healthy singleton fetuses were recruited consecutively and prospectively during routine first trimester scans in our unit. Two-dimensional (2D) images of nuchal translucency (NT), crown-rump length (CRL), and biparietal diameter (BPD) were obtained by following a standard protocol. The volume of the nuchal area (NV) was obtained by a 3D scanning machine.

RESULTS

The mean time to perform a 2D first trimester scan was 15.3 min, while the mean time to obtain and examine the stored volumes was 11.1 min (p<0.001) in a 3D scan. There were no significant differences in NT, CRL, and BPD between the two groups. Two cases with an NT thickness>2.5 mm also revealed increased volume data in the nuchal area. The Pearson's correlations between NT and CRL, BPD and CRL, NT and NV, and NV and CRL were moderate-to-high positive.

CONCLUSION

The nuchal volume data and the standard curve in the first trimester may be possible markers for Down syndrome screening. 3D scans can also minimize the scanning time, providing views not easily following strict NT guidelines.