C646 – Repeat consultation
OHIP Surgical Procedures Code — CONSULTATIONS AND VISITS · Schedule of Benefits
A specific assessment rendered by a General Thoracic Surgery specialist for a non-emergency in-patient in an acute care hospital. This service requires a full history of the presenting complaint and detailed examination of the affected part(s), region(s), or system(s) needed to make a diagnosis, and/or exclude disease, and/or assess function. As an assessment, it also includes the common elements of all insured services as outlined in the Schedule of Benefits on pages - and the specific elements of assessments on page .
When to Use
- Use C646 for a subsequent, non-emergency assessment of a thoracic surgery inpatient when a new clinical problem arises that requires a full history and physical examination.
- Use C646 when re-evaluating a patient's thoracic condition after a significant change in clinical status that necessitates a comprehensive reassessment beyond a standard subsequent visit (C648).
- Use C646 when managing a patient who has been transferred to your service for a new thoracic issue that requires a formal, documented consultative-level assessment.
Common Pitfalls
- Billing C646 when the documentation only supports a routine subsequent visit (C648); ensure the notes reflect a 'full history' and 'detailed examination' to avoid audit downgrades.
- Attempting to bill C646 on the same day as another assessment (e.g., A646 or C645) by the same physician, which will trigger an automatic rejection or adjustment to a single fee.
- Failing to account for the 12-month frequency limit; exceeding the defined limit per patient per physician will result in the claim being automatically adjusted to a lesser assessment fee.
Billing Tips
- If you spend significant time actively monitoring a patient post-assessment due to a thoracic complication, consider adding K001 in 15-minute increments, provided you document the time spent to the exclusion of other work.
- Always append the C101 premium if the assessment occurs within an ICU or CCU setting, as this is a flat-rate add-on that is payable alongside C646.
Effective: June 1, 2025
A. Consultations and Visits
CONSULTATIONS AND VISITS
Assessment
Hospital and Institutional Consultations and Assessments, Assessments
A full history of the presenting complaint and detailed examination of the affected part(s), region(s), or system(s) needed to make a diagnosis, and/or exclude disease, and/or assess function must be documented in the patient's medical record.
All insured services must be documented in appropriate medical records that establish the service was provided, the service claimed is the service rendered, and the service was medically necessary.
The amount payable for specific or medical specific assessments in excess of the per-patient per-physician per 12-month-period limit will be adjusted to a lesser assessment fee.
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