Project Summary/Abstract Diagnostic imaging is a standard part of trauma assessment, but access to imaging is often extremely limited in low and middle-income countries, where most injury deaths occur. Trauma death rates in Cameroon are higher than surrounding countries. Failure to diagnose hemorrhagic shock has been implicated in death analysis of the Cameroon Trauma Registry and by the National Trauma Quality Improvement Committee as a key root cause of preventable deaths. Currently, fewer than half of trauma patients in Cameroon receive diagnostic imaging. Development of a provider-performed smartphone-based ultrasonography (SBU) program for trauma could increase diagnostic access and facilitate timely diagnosis and treatment of injuries but only if it is feasible and effective for the Cameroonian context. The long-term goal of this research is to reduce the burden associated with injury in Cameroon. This study’s overall objective is to expand diagnostic capacity to facilitate timely diagnosis of injury and reduce injury burden. The study hypothesis is that implementation of a provider-performed SBU program is a feasible and effective method of expanding access to diagnostic imaging for trauma patients in Cameroon. To accomplish the objective, this study will pursue three specific aims for the R21 phase: 1) Evaluate the educational efficacy of a SBU training curriculum in short- and medium-term skill and knowledge acquisition among Cameroonian trauma providers; 2) Evaluate the feasibility of a provider- performed SBU pilot in Cameroon; 3) Assess the acceptability of an SBU pilot among Cameroonian trauma stakeholders. If the R21 transition milestones are met, the R33 phase will pursue three specific aims: 1) Assess diagnostic accuracy of provider-performed SBU on trauma patients; 2) Evaluate the effectiveness of a provider-performed SBU program in expanding diagnostic capacity for trauma; 3) Test associations between SBU program implementation and trauma outcomes. Validating SBU as a feasible and effective method to expand diagnostic capacity will remove a major roadblock to prompt trauma care and provide a critical target for reducing the detrimental impact of injury on this population. Embedded in the study approach is the training of clinicians in health systems research and strengthening of mHEALTH capacity in Cameroon which will support development and research across health sectors. A standardized SBU training and implementation protocol could be rapidly scaled-up for wider implementation throughout Cameroon and validated in other LMIC contexts.