OBJECTIVES To collect and present recently published methods of quantifying blood loss in orthopaedic trauma. DATA SOURCES A systematic review of English-language literature in PubMed, Cochrane Library, and Scopus databases was conducted according to PRISMA guidelines on articles describing methods of determining blood loss in orthopaedic trauma published since 2010. STUDY SELECTION English, full-text, peer-reviewed articles documenting intraoperative blood loss
in an adult patient population undergoing orthopaedic trauma surgery were eligible for inclusion. DATA EXTRACTION Two authors independently extracted data from included studies. Articles were assessed for quality and risk of bias using Cochrane Collaboration's tool for assessing risk of bias and ROBINS-I. DATA SYNTHESIS The included studies proved to be heterogeneous in nature with insufficient data to make data pooling and analysis feasible. CONCLUSIONS Eleven methods were identified: 6 unique formulas with multiple variations, changes in hemoglobin and hematocrit levels, measured suction volume and weighed surgical gauze, transfusion quantification, cell salvage volumes, and hematoma evacuation frequency. Formulas included those of Gross, Mercuriali, Lisander, Sehat, Foss, and Stahl, with Gross being the most common (25%). All formulas used blood volume estimation, determined by equations from Nadler (94%) or Moore (6%), and measure change in pre- and post-operative blood counts. This systematic review highlights the variability in blood loss estimation methods published in current orthopaedic trauma literature. Methods of quantifying blood loss should be taken into consideration when designing and evaluating research. LEVEL OF EVIDENCE Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.