Despite the widespread use of ultra-massive transfusion (UMT) as an intervention for trauma patients in hemorrhagic shock, no standard definition exists. We performed a systematic review to determine a consensus definition for UMT.

A search was performed from 1979 to 2022. The authors screened studies defining UMT and associated outcomes as defined by our prespecified PICO questions. The PRISMA guidelines were used.

1662 articles met criteria for eligibility assessment, 17 for full-text review and eight for data extraction. Only two studies demonstrated a consensus definition of UMT, which used ≥20 units of red blood cell product within 24hrs. Parameters associated with increased mortality included lower blood pressure, lower pulse and lower Glasgow Coma Score at the time of presentation and a higher injury severity score and undergoing a resuscitative thoracotomy.

The absence of a consensus definition for UMT raises challenges from clinical, research and ethical perspectives. Based on our findings, the authors advocate for the feasibility of standardizing the definition of UMT as ≥20 units of red blood cell product within 24hrs.