Methods of defining major haemorrhage after injury: A scoping review

Injury remains a significant global health concern, with early major haemorrhage (MH) being a leading cause of preventable death. However, the absence of a standardised definition for MH hinders research comparability and optimal clinical decision-making.

This scoping review aims to explore and categorise the published definitions of MH in adults following injury.

A systematic search of the Medline (OVID) database and additional sources was conducted following established guidelines. Peer-reviewed articles published in English up to March 2023 were included if they related to injury, and critically unwell adult patients, and included reference to bleeding or haemorrhage.

Out of 191 identified articles, 50 were included in the final analysis. These studies spanned from 2006 to 2023 and were conducted in various geographic locations. No consistent definition of MH was identified. Definitions of MH fell into six distinct categories: receipt of blood products, physiological parameters, scoring systems, clinical gestalt, observed bleeding (CT or clinical), and composite definitions. The ‘receipt of blood products’ category was the most frequent definition category, with massive transfusion (MT) ‘received’ being the most common definition of MH. Composite definitions and definitions involving the use of physiological parameters were also commonly employed.

Our scoping review identified wide heterogeneity in the definition of MH following injury. The absence of a standardised definition for MH poses a significant challenge to both injury research and clinical practice. Addressing this gap is crucial in improving systems of trauma care and outcomes for critically bleeding patients.