G121 – Impedance plethysmography - technical component
OHIP Diagnostic & Therapeutic Procedures Code — DIAGNOSTIC AND THERAPEUTIC PROCEDURES · Schedule of Benefits
G121 represents the technical component of impedance plethysmography. As per , this includes the provision of necessary equipment, supplies, personnel, and the responsibility for quality assurance of data acquisition and record-keeping. It is claimed separately from the professional component, G120. There are specific payment rules and restrictions when this service is performed in a hospital setting.
When to Use
- Use G121 when you own or lease the impedance plethysmography equipment and provide the technical staff to perform the test in an office setting.
- Use G121 in conjunction with G120 when you are performing the full diagnostic service, provided you maintain the required quality assurance documentation for the technical equipment.
Common Pitfalls
- Billing G121 at the full fee when the service is performed in a hospital setting, which triggers an automatic rejection or adjustment to 86.10% of the fee.
- Claiming G121 without maintaining verifiable records of equipment calibration and staff training, which are mandatory under the quality assurance requirements of GP11.
Billing Tips
- Ensure your billing software is configured to automatically apply the 86.10% reduction for hospital-based claims to avoid manual reconciliation errors.
Effective: April 1, 2026
J. Diagnostic and Therapeutic Procedures
DIAGNOSTIC AND THERAPEUTIC PROCEDURES
Diagnostic
Diagnostic and Therapeutic Procedures
The physician submitting a claim for the technical component is responsible for the complete quality assurance process for all elements of the technical component of the service, including data acquisition, reporting, and record keeping. The physician must be able to demonstrate the above upon request by the MOH.
The physician maintains documentation that describes the process by which the physician monitors quality assurance in accordance with professional standards.
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