The CPT® and ICD-10-CM codes that are reported for the procedure are 31575, 31231-59, J32.4 and J37.1 because the nasal endoscopy and laryngoscopy can be both performed via the nasal cavity.
The code 31575 is for Laryngoscopy/Fiberoptic/Diagnostic code. Next, CPT code 31231-59 describes a unilateral or bilateral procedure with modifier 59 is appended.
Moreover, in the Index to Diseases and Injuries, look for pansinusitis (chronic) and it will direct you to J32.4, which the doctor diagnose the patient of chronic pansinusitis and the code J37.1 is for laryngotracheitis/chronic that encompasses the LPR and the chronic laryngitis and tracheitis.