A cluster of choanal atresia.

During a 5-month period in 1991 four infants with choanal atresia or stenosis were born at one hospital. We therefore reviewed our experience of this condition during the past 6 years and compared the patients who presented before with the four clustered cases. No definite explanation has been ascertained for this cluster of cases of choanal obstruction but a viral or other environmental teratogen could not be excluded.