Figure 7: Extent of the resection of endonasal endoscopic frontal sinus drainage type IIa, IIb, III according to Draf.
Type IIa = resection of all anterior ethmoid cells obstructing the frontal sinus drainage pathway. Type IIb = type IIa + resection of the ipsilateral floor of the frontal sinus + the ipsilateral middle turbinate in front of the level of the posterior wall of the frontal sinus. Advanced type IIb = type IIb + resection of the frontal sinus septum (blue). Modified type III = type IIb + resection of the nasal septum (green) (+ resection of the contralateral medial floor of the frontal sinus (red) + resection of the complete contralateral floor of the frontal sinus and the contralateral middle turbinate in front of the level of the posterior wall of the frontal sinus if needed (yellow) (if present) + resection of the frontal sinus septum (blue) if needed). Type III = bilateral type IIb + resection of the adjacent nasal septum + resection of the frontal sinus septum.