ABSTRACT
Choanal atresia occurs in about 1 in 7000 births, so it is not rare. It occurs when the nasobuccal membrane of Hochstetter fails to involute, leaving a plate of tissue across the back of the nose, closing it off completely and separating it from the pharynx. The nose looks normal from the outside, but it is completely blocked to airflow on one or both sides. The atretic plate is made of bone, thick at the edges but quite thin in the middle. The central part may in fact be membranous rather than bony in 70 per cent of cases, although this membranous part is often quite small. Just over half of all cases are unilateral (Figure 67.1), the rest bilateral (Figure 67.2).
