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Updated: Aug 11, 2026
State of the Art Cranial Ultrasound Imaging in Neonates
Published on: February 2, 2015
Ultrasonographic evaluation of fetal nasal bone in a low-risk population at 11-13 + 6 gestational weeks
Domingo Ramos-Corpas1, Juan C Santiago, Francisco Montoya
1Servicio de Obstetricia y Ginecología, Hospital Universitario V. Macarena, Sevilla, Spain. ramoscor@arrakis.es
Objective:
To evaluate the utility of determining the presence/absence of nasal bone in a low-risk fetal population.
Methods:
Prospective study of the presence/absence of nasal bone among 1800 consecutive unselected fetuses, with complete follow-up of results.
Results:
An adequate sonographic evaluation of nasal bone was obtained in 1682 (93.44%) of the fetuses. Nasal bone was considered absent in 19 (1.06%) of 1790 fetuses with a normal karyotype and in 2 (28.57%) of the seven recorded cases of Down syndrome (DS). The overall first-trimester sensitivity for DS to the absence of nasal bone was two of the six cases (33.3%) and the false-positive rate was 1.13%. The positive predictive value for DS of the absence of nasal bone was 2/21 (9.52%).
Conclusions:
In a low-risk population, the evaluation of the presence/absence of nasal bone in DS screening during the first trimester has a low sensitivity. First-trimester assessment of the nasal bone in population screening may play a lesser role than in the re-evaluation of high-risk pregnancies.
