wounds, which are higher energy than stab wounds, are usually more damaging than the latter. Gunshot wounds that penetrate the peritoneum result in significant damage to major intra-abdominal structures in some 90 percent of cases. Pathophysiology Abdominal trauma can be life-threatening because abdominal organs, especially those in the retroperitoneal space, can bleed profusely, and the space can hold a great deal of blood. Solid abdominal organs, such as the liver and kidneys, bleed profusely when cut or torn, as do major blood vessels such as the aorta and vena cava. Hollow organs such as the stomach, while not as likely to result in shock from profuse bleeding, present a serious risk of infection, especially if such an injury is not treated promptly. Gastrointestinal organs such as the bowel can spill their contents into the abdominal cavity. Hemorrhage and systemic infection are the main causes of deaths that result from abdominal trauma. One or more of the intra-abdominal organs may be injured in abdominal trauma. The characteristics of the injury are determined in part by which organ or organs are injured. Liver The liver, the most vulnerable abdominal organ to all forms of injury because of its size and location (in the upper right quadrant of the abdomen), is injured in about five percent of all people admitted to a hospital for trauma. Liver injuries present a serious risk for shock because the liver tissue is delicate and has a large blood supply and capacity. The liver may be lacerated or contused, and a hematoma may develop. It may leak bile, usually without serious consequences. If severely injured, the liver may cause exsanguination (bleeding to death), requiring emergency surgery to stop the bleeding. Spleen Spleen is the most common cause of massive bleeding in blunt abdominal trauma to a solid organ. Spleen is the most commonly injured organ. A laceration of the spleen may be associated with hematoma. Because of the spleen's ability to bleed profusely, a ruptured spleen can be life-threatening, resulting in shock. However, unlike the liver, penetrating trauma to the spleen, pancreas and kidneys do not present as much of an immediate threat of shock unless they lacerate a major blood vessel supplying the organs, such as the renal artery. Fractures of the left lower ribs are associated with spleen lacerations in 20 percent of cases. Pancreas The pancreas may be injured in abdominal trauma, for example by