Fig. 3

Cross-over L-shaped flap for unilateral atresia (Each step is shown by Schematic diagram combined with real Endoscopic view). a Endoscopic view of the healthy cavity showing the horizontal incision on the top of the septum from posterior to anterior, about 5–10 mm in length, and the vertical incision on the septum connected to the horizontal incision. b Endoscopic view of the left nasal cavity showing the choanal atresia. The red dashed line marks the incision made at the septal continue to nasal floor, reaching the lateral nasal wall. c After elevation of healthy side of the septal mucosal flap, thickened vomer in the healthy cavity was removed. d After elevation of the L-shaped septonasal flap in the atresia side, the pharyngeal face of the atresia plates and the thickened vomer and parts of the lateral bone were removed. e The healthy side mucosal flap rotated to cross the middle septal line to cover the floor and the border of the neo-choana. f The atresia side mucosal flap was fashioned and covering the lateral and inferior raw surface