Trauma is the third most common cause of death in the United States and the leading cause of death of men and women under 40 years of age. Approximately 10% of all trauma deaths are due to abdominal injuries. The diagnosis of abdominal injuries due to blunt trauma is challenging because the injuries may not manifest themselves clinically during the initial assessment and because the presence of other more obvious injuries may divert the attention of the initial assessor from potentially life-threatening intra-abdominal pathology. Two different mechanisms may cause injury with blunt abdominal trauma: (1) compressive forces and (2) deceleration forces. Compressive forces result from blows or external compression against a fixed object, such as the spine. These forces can cause lacerations and subcapsular hematomas of solid parenchymal organs, such as the spleen and liver, or they can deform and increase the intraluminal pressure in hollow organs, such as the bowel, resulting in rupture. Deceleration injuries cause stretching and linear shearing forces between fixed and more freely moveable objects resulting in lacerations or injuries of structures, such as the renal arteries and mesenteric blood vessels. Penetrating injuries may be produced by a variety of devices, such as knives and high-velocity projectiles; each is associated with a different injury pattern. Approximately one third of stab wounds penetrate the peritoneal cavity and any organ in the path of the penetrating object may be injured.