FIELD : medicine.SUBSTANCE : group of inventions relates to medicine. After the formation of the choanostoma, the upper and lower septal flaps are formed from the mucous membrane. Upper flap is placed in the region of the base of the sphenoid sinus. Lower flap is placed on the bottom of the nasal cavity in the area of the resected fragment of the vomer. And after laying the septal flaps on the wound surfaces, YAMIK sinus catheter is inserted into the cavity of the nasal passage to press the flap tissues to the wound surfaces by expanding the diameter of the canister with its inflation.EFFECT : group of inventions allows the fixation of mucosal flaps in the choana in patients after choanoplasty, to improve the results in the long-term period, improve the quality of life of children in the postoperative period by using YAMIK sinus catheter for pressing the flap tissue to the wound surfaces due to the expansion of the diameter of the balloon by inflating it.2 cl, 2 dwg, 2 ex