Mechanism of injury (MOI) refers to the forces and events that caused a patient’s injuries. Understanding how an injury occurred helps providers anticipate potential injuries, prioritize assessment findings, and identify life-threatening conditions that may not be immediately visible.

Common mechanisms of injury include:

• Blunt Trauma: Injuries caused by impact or force without penetration of the skin, such as motor vehicle collisions, falls, assaults, or sports injuries.
• Penetrating Trauma: Injuries caused by an object breaking the skin and entering the body, including gunshot wounds, stab wounds, and impalements.
• Blast Injuries: Injuries resulting from explosions that may produce multiple injury patterns, including pressure wave injuries, penetrating trauma from debris, blunt trauma, and burns.

Mechanism of injury does not diagnose specific injuries, but it guides the assessment process and helps providers maintain a high index of suspicion — even when obvious signs of injury are limited.

Remember: A strong understanding of mechanism of injury allows providers to identify potential life threats earlier and make more informed treatment and transport decisions.