Choanal atresia is a congenital disorder where the back of the nasal passage (choana) is blocked, usually by abnormal bony or soft tissue (membranous) due to failed hole development of the nasal fossae during prenatal development.

Choanal atresia is diagnosed based on the inability to place a nasal catheter, and radiology results (particularly CT scans).

[1] Choanal atresia is caused by problems with the development of the nasal cavity and the palate.

[3] One study suggests that chemicals that act as endocrine disrupters may put an unborn infant at risk.

A 2012 epidemiological study looked at atrazine, a commonly used herbicide in the U.S., and found that women who lived in counties in Texas with the highest levels of this chemical being used to treat agricultural crops were 80 times more likely to give birth to infants with choanal atresia or stenosis compared to women who lived in the counties with the lowest levels.

[4] Another epidemiological report in 2010 found even higher associations between increased incidents of choanal atresia and exposure to second-hand-smoke, coffee consumption, high maternal zinc and B-12 intake and exposure to anti-infective urinary tract medications.

[5] The anti-thyroid medication methimazole has been associated with the development of choanal atresia in rare cases if given during the first trimester of pregnancy.

[6] Choanal atresia causes closure of the posterior choanae in the nasal cavity.