Choanal atresia: a new anatomic classification and clinical management applications.

The anatomic classification of choanal atresia is commonly quoted as 90% bony and 10% membranous. This incidence is from a review by Fraser in 1910 of 115 cases, "many of which were insufficiently described." We have reviewed 47 computed tomography scans of choanal atresia from the literature and 16 from our clinical experience, and classified the anatomy as bony, mixed bony-membranous, or pure membranous. Our results reveal a combined incidence of 18 (29%) pure bony, 45 (71%) mixed bony-membranous, and no pure membranous atresia. We propose a new classification of choanal atresia to include bony, mixed, and membranous to accurately reflect the anatomic abnormalities. Our series of 11 patients undergoing transnasal microsurgical repair, a critical review of the literature, and the implications of the anatomic classification on the choice of surgical procedure are presented.