Evaluation of fetal nasofrontal angle in the second trimester in normal pregnancies.

PURPOSE: The nasal bone is one of the important fetal structures to be radiologically evaluated in the first and second trimesters. In this study, we aimed to evaluate the nasal root and to determine the normal range of the naso-frontal angle, which may potentially be used as a predictive or diagnostic parameter in the diagnosis of the above-mentioned syndromes or other congenital abnormalities with associated nasal features using obstetric ultrasonography in normal fetuses. METHODS: We evaluated the naso-frontal angle using transabdominal ultrasonography in 195 healthy fetuses between the 18(th) and 21(st) weeks of gestation. The measurements were performed with the fetal neck in mild flexion and three echogenic lines (nasal end, skin on the nasal bone, nasal bone) visualized. RESULTS: The minimum, maximum and mean naso-frontal angle values were 110°, 143° and 128°, respectively, between the 18(th) and 21(st) weeks of gestation. Linear regression analysis showed no association between NFA and gestational week (Beta = 0.020 p = 0.786). CONCLUSIONS: The normal range of NFA between the 18(th) and 21(st) weeks of gestation was determined in this study. The association between NFA measurements and various congenital anomalies or fetal outcomes remains to be investigated.