Significance: Traumatic pelvic bleeding is a significant cause of morbidity and mortality, and many patients die from potentially survivable injuries. These injuries claim up to 40,000 lives every year in the United States. This fact highlights an emergent need for innovative technologies to control bleeding in the most severely injured patients. Approach: This FastTrack SBIR application will develop novel, self-expanding polyurethane foam systems for treatment of exsanguinating pelvic hemorrhage. In Phase I of the proposal, Arsenal Medical will collaborate with Massachusetts General Hospital (MGH) to create a novel, clinically relevant animal model of pelvic hemorrhage. A trimodal approach incorporating vascular injury, soft-tissue injury, and tissue disruption will be utilized. To estabish baseline performance and areas for optimization, existing treatments will be tested, including Arsenal Medical's ResQFoam technology (designed for intraabdominal use). In Phase II of the proposal, a foam will be developed for efficacy and removal in the pelvic space by modulating open-cell microstructure and improving foam mechanical properties (tensile strength, elasticity) of the polyurethane struts. The appropriate dose of this self-expanding foam for effectiveness in pelvic bleeding will be determined through a dose ranging study. The net result will be an effective biomaterial intervention for treatment of pelvic bleeding. After optimizing the foam, a comprehensive physiological study of ischemia-reperfusion dynamics will be conducted. Phase II will culminate in the preparation of a preliminary regulatory submission to the FDA. Innovation: The trauma community lacks a robust animal model for the assessment of therapeutics, surgical approaches, and devices for the treatment of pelvic hemorrhage. Establishing this animal model, as well as critical research in ischemia-reperfusion injuries, will provide substantial benefit to the trauma community. Self-expanding foam treatment will be effectively developed for clinical use in retroperitoneal pelvic bleeding based on the aims of this proposal, resulting i a new life-saving therapy. An established, productive interdisciplinary team, established regulatory pathway, and existing manufacturing infrastructure increase the probability of success and commercialization of self-expanding foams for pelvic trauma. The proposed research will develop the first closed-cavity, lethal model of pelvic exsanguination and create a minimally invasive foam platform for pelvic hemostasis that will be superior to the existing standard of care.