Evaluation of fetal nasal bone length during 18<sup>+0</sup>-23<sup>+6</sup> gestational weeks

Abstract

Purpose: To establish the nomograms of fetal nasal bone length reported the ethnic differences and relationship between chromosomal abnormalities, between 18+0-23+6 gestational weeks.Material and Method: In this study, 2653 fetus between 18+0-23+6 gestational weeks had normal US findings and had not postnatal anomaly were retrospectively evaluated between January 2009 and September 2014. After detailed fetal anomaly scan, biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), nasal bone (NB) length and mean gestational weeks (GW) of each fetus were recorded. Regression analyses were performed between NB length and GW, BPD, HC, AC and FL. The reference values for 5-10-25-50-75-90-95. percentiles were established for each gestational week.Results: In this study, 27 twin pregnancies were detected in the 2626 pregnant women (age range, 17–46 years; mean age, 30.02 ±5.78 years). There were 159, 214, 528, 599, 563, 583 fetuses and the mean NB lengths were 5.5 ± 0.85, 6.3 ± 0.83, 6.6 ± 0.81, 6.9 ± 1, 7.1 ± 0.86, 7.6 ± 0.89 (minimum 4 mm and maximum 10.1 mm) between 18+0-23+6 gestational weeks, respectively. NB length was increased linearly consistent with GH, BPD, HC, AC and FL during 18+0-23+6 gestational weeks. In correlation analysis, the fetal NB length were significantly correlated with GW, BPD, HC, AC and FL (p<0.001).Conclusion: In our study, we established the NB length nomogram in healthy fetuses between 18+0-23+6 gestational weeks. We think that this reference values can be used for diagnosis of nasal bone hypoplasia in prenatal screening.