Canada’s Transfusion Error Surveillance System (TESS)

Written by:

Akash Gupta, MD FRCPC DRCPSC CTBS Transfusion Medicine Specialist, Precision Diagnostics and Therapeutics Program (Laboratory Medicine), Sunnybrook Health Sciences Centre , Medical Officer, Canadian Blood Services

At the surface, the administration of blood products requires that we issue the right product to the right patient at the right time. However, behind this apparent simplicity, there is a complex series of events where errors can occur, including collection and production with the blood manufacturer, patient testing and issuing at the blood bank, and ordering and administration with the clinical team. To catch these mistakes and correct the systematic issues that cause them, we rely on our hemovigilance systems. In Canada, that role is filled by the Transfusion Error Surveillance System (TESS), a national program that plays a crucial role in transfusion safety.

TESS was launched in 2005 by the Public Health Agency of Canada (PHAC), as a result of the Krever Commission (X). The commission enforced the idea that the safety of our blood supply was not based solely on testing of the products, but also monitoring how transfusions are ordered, prepared, and administered. The program started with 11 hospitals and by 2008 had evolved into a national surveillance system with 15 hospitals in 4 Canadian provinces and territories acting as sentinel sites and reporting all errors identified. The involved sites account for approximately 16% of the blood transfusion activities in Canada.

TESS collects non-nominal, standardized data on transfusions errors and classifies them as near misses (not reaching the patient) or actual events, which are further classified as causing harm or no harm. The 2012-2016 TESS report summarized 50,000 errors, with 95% classified as near-miss events and 93% of those as planned discovery events. A more recent report from 2022, summarizing approximately 10,000 errors, had 92% of errors classified as near miss and only 3 events (0.4%) causing patient harm. In addition to confirming the overall safety of blood transfusion in Canada, the aggregate data from these reports is helpful in identifying sources of potential errors or contributing factors to repeated near-miss events. For example, the 2012-2016 TESS report highlights that the greatest number of errors occur with sample collection (34% of all errors reported).

The planned sunsetting of the Transfusion Error Surveillance System represents a significant transition point for transfusion safety in Canada. Over nearly two decades, TESS has provided a national lens on transfusion errors, enabling hospitals to benchmark performance, identify systemic vulnerabilities, and demonstrate that most errors are intercepted before patient harm occurs. The loss of this coordinated national surveillance framework risks creating gaps in our collective understanding of error patterns and trends, particularly for near misses that rarely surface through adverse reaction reporting alone. As Canada moves forward, sustaining the gains achieved through TESS will require renewed commitment to local error reporting, strong hospital-based hemovigilance programs, and consideration of alternative national or provincial mechanisms to ensure continued learning, transparency, and improvement in transfusion practice. Without such efforts, the quiet safety successes fostered by TESS may become harder to measure—and harder to maintain.