Summary & Overview
HCPCS M0243: Casirivimab and Imdevimab Infusion or Injection
HCPCS Level II code M0243 denotes the administration of casirivimab and imdevimab by intravenous infusion or subcutaneous injection, inclusive of the procedure and post-administration monitoring. This code captures delivery of a paired monoclonal antibody therapy used in clinical practice for passive immunotherapy and is relevant for outpatient infusion venues nationwide. Its use affects billing workflows, payer coverage decisions, and facility resource planning for infusion and observation services.
Key payers addressed in the analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find national benchmarks for utilization and coverage policy context, typical sites of service and operational considerations for outpatient infusion delivery, and coding implementation notes tied to HCPCS Level II reporting. The summary highlights where data are available and notes where input fields are absent.
The publication provides a concise reference for revenue cycle, clinical operations, and policy teams seeking clarity on how M0243 should be categorized in claims, what service it represents clinically, and which major payers are commonly engaged in coverage and reimbursement decisions for monoclonal antibody infusion services.
Billing Code Overview
HCPCS Level II code M0243 describes an intravenous infusion or subcutaneous injection of casirivimab and imdevimab, and explicitly includes the infusion or injection procedure plus post-administration monitoring. The service type is therapeutic monoclonal antibody administration for passive immunotherapy. The typical site of service is outpatient infusion settings such as ambulatory infusion centers, hospital outpatient departments, physician offices, or other outpatient clinics where intravenous infusions or subcutaneous injections and ensuing observation are provided.
Data not available in the input.
Clinical & Coding Specifications
Clinical Context
A 68-year-old patient with multiple comorbidities (type 2 diabetes, chronic obstructive pulmonary disease, and hypertension) presents to an outpatient infusion clinic after testing positive for SARS-CoV-2 and meeting high-risk criteria for progression to severe COVID-19. The clinician documents indication for monoclonal antibody therapy and orders M0243 for administration of casirivimab and imdevimab via intravenous infusion with post-administration monitoring.
The clinical workflow: the patient is pre-screened by nursing for allergies and vital-sign stability, consent is obtained, and baseline vitals are recorded. A pharmacy prepares the monoclonal antibody product per manufacturer guidance. An infusion nurse places an IV, administers the infusion per protocol, observes for infusion-related reactions during and after administration, documents start and stop times, and provides discharge instructions. If an adverse reaction occurs, the nurse initiates emergency protocols, documents interventions, and may bill appropriate modifiers if services are unusual or discontinued.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
11 | PBI (Primary benefit) | Use when this service is the primary procedure for the encounter and payer requires designation of primary service. |