The management and treatment of a trauma patient begins immediately at the scene, in the out-of-hospital phase, and determines the outcome for the patient, as well as influence the overall success of the trauma clinical pathway. When the trauma team enters the scene to take care of the patient, the first crucial step to be taken as an immediate priority is the size-up of the scene. This is to guarantee the safety of the team itself, its understanding of the scene, and the situation of the event. The scene size-up is as essential as the first approach to the scene. When the Emergency Medical Services (EMS) team first approaches the patient, it is crucial for all healthcare professionals to understand what to look out for and how to assess the condition of a patient using a systematic approach. Having a systematic method is essential for a rapid assessment, thus minimizing the chance of failing to spot injuries, avoiding mistakes, and wasting time. It is important for the patient assessment to be prioritized urgently and undertaken to recognize all the critical problems so one can act quickly to avoid any deterioration. This assessment must establish what and where the problem is, what the impact of the problem is, how to quickly manage the situation, as well as gathering the information needed. Healthcare providers are required to evaluate trauma patients quickly, address major life threats, and make a full inventory of injuries.