ImportanceManagement of hemodynamically unstable pelvic fractures remains a challenge. Hemostatic interventions are used alone or in combination. There is a paucity of data on the association between the pattern of hemorrhage control interventions and outcomes after a severe pelvic fracture.ObjectiveTo characterize clinical outcomes and study the patterns of hemorrhage control interventions in hemodynamically unstable pelvic fractures.Design, Setting, and ParticipantsIn this cohort study, a retrospective review was performed of data from the 2017 American College of Surgeons Trauma Quality Improvement Program database, a national multi-institutional database of trauma patients in the United States. Adult patients (aged ≥18 years) with pelvic fractures who received early transfusions (≥4 units of packed red blood cells in 4 hours) and underwent intervention for pelvic hemorrhage control were identified. Use and order of preperitoneal pelvic packing (PP), pelvic angioembolization (AE), and resuscitative endovascular balloon occlusion of the aorta (REBOA) in zone 3 were examined and compared against the primary outcome of mortality. The associations between intervention patterns and mortality, complications, and 24-hour transfusions were further examined by backward stepwise regression analyses. Data analyses were performed in September 2021.Main Outcomes and MeasuresPrimary outcomes were rates of 24-hour, emergency department, and in-hospital mortality. Secondary outcomes were major in-hospital complications.ResultsA total of 1396 patients were identified. Mean (SD) age was 47 (19) years, 975 (70%) were male, and the mean (SD) lowest systolic blood pressure was 71 (25) mm Hg. The median (IQR) Injury Severity Score was 24 (14-34), with a 24-hour mortality of 217 patients (15.5%), ED mortality of 10 patients (0.7%), in-hospital mortality of 501 patients (36%), and complication rate of 574 patients (41%). Pelvic AE was the most used intervention (774 [55%]), followed by preperitoneal PP (659 [47%]) and REBOA zone 3 (126 [9%]). Among the cohort, 1236 patients (89%) had 1 intervention, 157 (11%) had 2 interventions, and 3 (0.2%) had 3 interventions. On regression analyses, only pelvic AE was associated with a mortality reduction (odds ratio [OR], 0.62; 95% CI, 0.47 to 0.82; P < .001). Preperitoneal PP was associated with increased odds of complications (OR, 1.39; 95% CI, 1.07 to 1.80; P = .01). Increasing number of interventions was associated with increased 24-hour transfusions (β = +5.4; 95% CI, +3.5 to +7.5; P < .001) and mortality (OR, 1.57; 95% CI, 1.05 to 2.37; P = .03), but not with complications.Conclusions and RelevanceThis study found that among patients with pelvic fracture who received early transfusions and at least 1 invasive pelvic hemorrhage control intervention, more than 1 in 3 died, despite the availability of advanced hemorrhage control interventions. Only pelvic AE was associated with a reduction in mortality.