CPT code 87181 represents a laboratory technical procedure to assess a microbial culture isolate’s susceptibility to a specific antimicrobial agent using a gradient diffusion test on an agar plate. This test informs targeted antimicrobial therapy, supports antimicrobial stewardship, and has broad clinical importance for infection management across inpatient and outpatient settings. Nationally, accurate reporting of this code affects laboratory service tracking, quality measurement, and reimbursement for microbiology testing.

Key payers referenced in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context for CPT code 87181, typical sites of service, and the service type. The publication outlines expected benchmarks and utilization patterns, common modifier usage, and policy updates relevant to lab billing and documentation where available. The content provides guidance on coding context, operational implications for clinical laboratories, and considerations for payers and compliance teams. Data not available in the input is noted where applicable.