S0145 Injection Pegylated Interferon — HCPCS Reimbursement

HCPCS Level II code S0145 denotes the injection of pegylated interferon alfa-2a at a concentration of 180 mcg per ml, a biologic injectable used in antiviral and immunomodulatory treatment regimens. This code matters nationally because it identifies billing for an expensive specialty drug administered in outpatient settings, affecting coverage decisions, prior authorization processes, and reimbursement across major payers. Key payers covered in this summary include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.

Readers will learn what the code represents clinically and operationally, which payers commonly process claims for this service, and the types of benchmarks and policy topics typically associated with specialty injectable drugs—such as utilization, site-of-service considerations, and payer coverage policies. The publication provides benchmarking context where available, notes common administrative considerations for billing and claims processing, and outlines policy developments that commonly impact similar HCPCS Level II drug codes. Data not available in the input is noted where specific benchmarks, taxonomies, ICD-10 pairings, and detailed payer policy variations would normally be described.

Billing Code Overview

HCPCS Level II code S0145 represents an injection of pegylated interferon alfa-2a, 180 mcg per ml. The service is an injectable biologic medication administration, typically billed for the provision of the drug itself when administered to a patient. The likely service type is a medication infusion/injection, and the typical site of service is an outpatient clinic, physician office, or infusion center where injectable antivirals or biologic therapies are administered.

Data not available in the input.

Clinical Context

A typical patient is an adult with chronic hepatitis C infection or other off-label viral indications being treated with pegylated interferon alfa-2a via subcutaneous injection at a dose of 180 mcg/mL. The patient presents to an outpatient infusion clinic, specialty pharmacy clinic, or physician office for scheduled therapy every week. Clinical workflow: review of current labs (CBC, liver panel, viral load), confirmation of weight and dose, assessment for contraindications and adverse effects (depression, cytopenias, flu-like symptoms), obtain informed consent for therapy, document dose and lot number, prepare and label the syringe, administer the subcutaneous injection (often in the abdomen or thigh), observe the patient briefly for immediate reaction, and document injection site and patient tolerance in the medical record. Typical site of service: outpatient infusion center, hematology/oncology or infectious disease clinic, specialty pharmacy clinic, or physician office providing injectable therapy.

Coding Specifications

Modifier	Description	When to Use
`00`	No modifier present	Standard billing when no modifier applies.
`22`	Increased procedural services	Use when work or resources substantially exceed typical for medication administration (rare for standard subcutaneous injection).

Taxonomy Code	Specialty	Notes
`208000000X`	Internal Medicine	Physicians managing chronic hepatitis C and systemic antiviral therapy.
`207RC0000X`	Infectious Disease	Specialists prescribing and overseeing interferon therapy.
`208600000X`	Hematology & Oncology	Specialists who may manage interferon-based regimens for hematologic or oncologic indications.
`363A00000X`	Nurse Practitioner	Commonly administers and documents subcutaneous injections in clinic settings.
`369000000X`	Physician Assistant	May perform or assist with administration and documentation of injectable therapy.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`B18.2`	Chronic viral hepatitis C	Primary indication for pegylated interferon alfa-2a therapy in historical treatment regimens.
`B18.1`	Chronic viral hepatitis B without delta-agent	Interferon may be used for certain hepatitis B treatment regimens.
`D72.8`	Other specified disorders of white blood cells	Monitoring for cytopenias is required during interferon therapy; relevant when abnormal counts occur.
`F32.9`	Major depressive disorder, single episode, unspecified	Depression is a known adverse effect of interferon therapy; screening and documentation are relevant.
`Z79.899`	Other long term (current) drug therapy	Used to indicate ongoing antiviral pharmacologic management when applicable.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`96372`	Therapeutic, prophylactic, or diagnostic injection (specify substance or drug); subcutaneous or intramuscular	Common code for administration of a single subcutaneous injection of pegylated interferon alfa-2a in clinic.
`36415`	Collection of venous blood by venipuncture	Often performed prior to injection to obtain baseline CBC and liver function tests.
`99000`	Handling and/or conveyance of specimen for transfer from physician's office to a lab (if used)	Used when specimens are sent to an external laboratory as part of pre-injection monitoring.
`99406`	Smoking and tobacco use cessation counseling visit, intermediate, greater than 3 minutes up to 10 minutes	Counseling codes may be used for behavioral counseling often provided alongside chronic disease management when applicable.
`99401`	Preventive medicine counseling and/or risk factor reduction intervention(s) provided to an individual (15 minutes)	Patient education or counseling related to therapy adherence and side-effect management.

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Summary & Overview

HCPCS S0145: Injection of Pegylated Interferon Alfa-2a, 180 mcg per ml