Purpose: To evaluate the outcomes of fetuses diagnosed with absent nasal bone in the second trimester.
Methods: This prospective, observational study included all fetuses who were diagnosed at or referred to our fetal medicine center with an absent nasal bone from 16 weeks onwards from November 2017 to December 2019. Amniocentesis for fetal karyotype and microarray was offered to all women. Women who opted not to undergo invasive testing were also followed up and neonatal outcome noted.
Results: 26 fetuses were eligible for inclusion in the study. 8 (30.8%) out of these were diagnosed with aneuploidy: 7 with trisomy 21 and one with trisomy 18. All fetuses with aneuploidy had additional ultrasound abnormality and/or high risk on biochemical screening.
Conclusions: Isolated absent nasal bone in the second trimester with prior low risk on combined screening performed by certified sonographers is unlikely to be associated with Down syndrome.
Keywords: Down syndrome; fetal ultrasound; maternal serum screening; nasal bone; obstetrics; second trimester.
© 2020 Wiley Periodicals, Inc.