Summary & Overview
HCPCS C9489: Injection, nusinersen, 0.1 mg
HCPCS Level II code C9489 denotes the supply unit for nusinersen, specified as an injection of 0.1 mg. Nusinersen is a disease-modifying therapy administered intrathecally for spinal muscular atrophy and has significant implications for specialty drug billing, utilization management, and hospital outpatient pharmacy operations. Nationally, accurate use of C9489 affects claims adjudication for high-cost biologic therapy and tracking of drug utilization across payers.
This analysis covers common national payers including Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of billing benchmarks and payer coverage considerations, summaries of relevant policy and reimbursement context, and clinical service-line implications for neurology and infusion/ambulatory surgical settings. The publication highlights how C9489 is recorded on service lines, typical sites of administration, and where data limitations exist.
The report is intended for revenue cycle managers, hospital pharmacy directors, clinical coders, and policy analysts who need concise guidance on coding and billing practices for nusinersen injections. It presents benchmarks, notes on policy updates, and operational considerations to support consistent documentation and claims processing at the national level.
Billing Code Overview
HCPCS Level II code C9489 represents Injection, nusinersen, 0.1 mg. This code describes the administered drug nusinersen in 0.1 mg dosage units and is used to bill for the medication component of patient care.
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Service type: Drug administration (intrathecal medication dosing derived from the drug description)
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Typical site of service: Hospital outpatient department or ambulatory infusion/clinic setting where intrathecal injections are performed
Clinical & Coding Specifications
Clinical Context
A typical patient is a pediatric or adult with spinal muscular atrophy (SMA) receiving intrathecal administration of nusinersen (C9489, injection, nusinersen, 0.1 mg). The clinical workflow begins with a neuromuscular clinic visit documenting SMA diagnosis, baseline motor function testing, and informed consent. Prior to the procedure, the patient undergoes pre-procedure assessment including vital signs, review of coagulation status, and any spinal imaging review if scoliosis or spinal hardware is present. On the day of service, the patient is positioned in the lateral decubitus or seated flexed position for a lumbar puncture. A lumbar puncture tray, aseptic technique, and fluoroscopic guidance may be used for difficult anatomy. The clinician withdraws a small volume of cerebrospinal fluid for laboratory checks if required, then administers the prescribed dose of nusinersen intrathecally. Post-procedure monitoring includes observation for headache, back pain, neurologic changes, and vital sign stability. Follow-up appointments document motor milestone response and schedule the next loading or maintenance dose according to the nusinersen dosing regimen.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
25 | Significant, separately identifiable evaluation and management (E/M) service by the same physician on the same day of the procedure | Use when a distinct E/M visit is provided on the same day as the intrathecal injection and documentation supports separate services |