CPT code 87186 represents laboratory antimicrobial susceptibility testing by dilution methods, a core microbiology service that determines minimum inhibitory concentrations (MICs) for culture isolates. This testing informs antimicrobial therapy selection and surveillance of resistance patterns, making it an essential diagnostic service across inpatient and outpatient settings nationwide. The code covers technical laboratory work using agar or microdilution techniques to observe organism growth across antibiotic concentrations.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a national-focused overview of clinical context for dilution-based susceptibility testing, typical sites of service, and common billing considerations. The publication outlines commonly observed payer coverage patterns, billing modifiers used in practice, and service-line implications for hospital and reference laboratories.

The content provides benchmarks and policy-relevant points for laboratory managers and revenue cycle staff, including where 87186 fits within microbiology service coding, operational implications for lab workflows, and elements that affect claims processing. Data not available in the input is noted where specific payer policies, fee schedules, or taxonomies are required but not provided.