The absence of nasal bones in the first trimester ultrasound scan in fetal trisomies

Objective The visualisation of nasal bones (NB) is one of the main points of ultrasound fetal assessment between 11 and 13 +6 weeks of gestation. Several studies demonstrated high association between absent nasal bone in the first trimester of pregnancy and abnormal fetal karyotype. The aim of the study was to assess the usefulness of the first trimester nasal bones visualisation in screening of the fetal aneuploidies.