CPT code 89190 denotes a laboratory microscopic examination of a nasal smear to detect eosinophils, cells that rise in number with allergic reactions and some parasitic infections. This clinical test aids diagnosis and management of allergic rhinitis, nasal eosinophilia, and related conditions; it is a focused, low-complexity laboratory procedure with implications for allergy and ENT care nationwide. Nationally, such targeted laboratory services support appropriate diagnosis, guide therapy choices (for example, topical versus systemic treatments), and can affect downstream utilization of allergy testing and specialist referrals.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context, common sites of service, and the typical role of this test in patient evaluation. The publication includes benchmark considerations, coding and billing context for outpatient laboratory settings, and policy-relevant notes about coverage trends and utilization management approaches. Data not provided in the input (such as payer-specific reimbursement rates, associated taxonomies, and ICD-10 mappings) are noted as unavailable where applicable.