Objective. Primary chronic rhinosinusitis (CRS) is typically a diffuse process and the extent of endoscopic sinus surgery (ESS) performed for medically recalcitrant CRS is impacted by many factors. However, some third-party payors have implemented policies to authorize coverage for ESS in a sinusby-sinus manner based on a minimal measurement of millimeters of mucosal thickening or sinus opacification in the corresponding sinus that is being surgically addressed. Our objective was to determine whether such policies are based on scientific evidence that in patients with medically recalcitrant CRS, a minimum measurement of mucosal thickening or sinus opacification is a predictor of CRS in that sinus or improved outcomes after ESS on a sinus-by-sinus basis.