Abstract

OBJECTIVE:

To evaluate the maternal ethnic influence and the intra and interobserver reproducibility of the nasal bone length measurement at 11-15 weeks of gestation in a Brazilian population.

METHODS:

A cross-sectional study with 171 normal pregnant women at 11-15 weeks was performed. Nasal bone was transabdominally measured in all cases. The patients were separated into three racial groups (White, Black and Asian) according to maternal ethnicity. The intraobserver variability was calculated through the repeated measurement of 55 fetuses by a single observer, and the interobserver variability was calculated through 44 measurements by two observers. The ANOVA test was used to compare the three racial groups. To calculate the variability, the intraobserver correlation coefficient (intra-CC), the interclass correlation coefficient (inter-CC) with 95% confidence interval, and the Bland-Altman plots were used.

RESULTS:

No statistically significant difference could be observed among the three races as for nasal bone length measurement (P = 0.934). The intraobserver variability was considered very good [intra-CC 0.92-IC 95% (0.902; 0.947)], as well as the interobserver variability [inter-CC 0.91-IC 95% (0.873; 0.940)].

CONCLUSIONS:

There is no significant difference in nasal bone length measurement among the three races analyzed. Nasal bone length measurement is reproducible.