**6. Conclusions**

In this study of subjects of chronic rhinosinusitis (CRS) undergoing functional endoscopic sinus surgery (FESS), we determined which clinical features are associated with higher possibility for revised surgery. We have developed an eight-step standard procedure to perform FESS in order to eliminate the bias of surgical technique. Sinus wall thickness and blood eosinophilia are associated with the need for revision surgery. Thickness of posterolateral sinus wall of more than 3.03 mm in maxillary sinus indicates the higher possibility for revised surgery. Also, CRS patients with thickened sinus walls were found to have poorer outcomes.

## **Acknowledgements**

This study was supported by a grant (100-2314-B-002-044) from the Ministry of Science and Technology (MOST) of the Republic of China.

## **Conflict of interest**

There are no financial or other relationships that could lead to a conflict of interest.
