First-Trimester Assessment of the Nasal Bones Using the Retronasal Triangle View

Abstract

This study shows that the nasal bones can be confidently identified as paired echogenic structures located at the upper tip of the retronasal triangle. This coronal view of the fetal face offers the possibility of screening for the presence or absence of the nasal bones in the first trimester, especially when the standard midsagittal views of the fetal face are suboptimal because of fetal or maternal factors. Because both nasal bones can be evaluated simultaneously in the coronal plane, the retronasal triangle view may be advantageous over the conventional midsagittal view assessment, in which only 1 of the 2 nasal bones is evaluated.