Transfusion and transplantation-related adverse events: Transfusion errors

Data on errors that occur during the transfusion process in Canada. Information on this page is based on 2024 data from the Transfusion Error Surveillance System (TESS) project.

  • Last updated: 2026-04-02

Transfusion Error Surveillance System (TESS) project

TESS collects data on errors that occur during the transfusion process. Data collected through TESS can help to identify and evaluate preventive measures to improve the transfusion process and patient safety. The voluntary surveillance system was initiated by the Public Health Agency of Canada in 2005. TESS monitors 4 provinces and 16% of blood transfusion activities in Canada.


Key findings

Number of errors reported in 2024

10,331

Number of errors that resulted in harm in 2024

16

About these data tiles
  • Tile 1: 10,331 errors, (e.g. blood sample labelled with incorrect patient identification) were reported in the year of 2024.
  • Tile 2: 0.16% of all reported errors resulted in harm to the patient.

Results

Overall counts of reported errors for 2024
Notes

Errors (10,331; 100%) are classified as near-miss events or actual events:

  • Near-miss events (9,362; 90.6%) are errors that were caught before they caused any harm. They are split into two groups based on how the error was found:
    • Planned discovery (9,289; 99.2%): The error is detected by a standardized mechanism or process.
    • Unplanned discovery (73; 0.8%): The error is detected by chance.
  • Actual events (969; 9.4%) refer to errors or deviations from standard procedures or policies that reached the patient or caused an impact. These events are categorized based on patient outcomes:
    • Harm (16; 1.7%): The patient experienced an unintended or inadequate response to the transfusion or suffered a negative impact or adverse transfusion reaction due to the error.
    • No harm (953; 98.3%): The patient did not experience any known negative clinical consequences at the time of reporting.
Location of error occurrence
Harm caused by errors, TESS 2024

Implication

Reporting and investigating errors in both transfusion services and clinical settings help identify and control risks before resulting in harm to the patient, thus providing opportunities to improve transfusion safety.


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