Early Transient Prenatal Ultrasound Features of Choanal Atresia.

We present a case series of early second-trimester prenatal ultrasound (US) features in 4 fetuses with a confirmed diagnosis of choanal atresia. The clinical characteristics and outcomes evaluated included prenatal US findings, genetic analyses, postmortem autopsies (2 cases), and computed tomographic findings. A transient large nasal cavity was detected by US in all 4 fetuses. This finding disappeared a few weeks later. Three cases were unilateral choanal atresia, and 1 was bilateral. Transient enlargement of the nasal cavity in early pregnancy appears to be a US sign of choanal atresia.