title: Nasal bone in screening for trisomy 21: defining hypoplasia.
authors: Jiri
authors: J
authors: Sonek
mesh_terms: D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D009295:Nasal Bone / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D016216:Ultrasonography, Prenatal