People with penetrating abdominal trauma may have signs of hypovolemic shock (insufficient blood in the circulatory system) and peritonitis (an inflammation of the peritoneum, the membrane that lines the abdominal cavity). Penetration may abolish or diminish bowel sounds due to bleeding, infection, and irritation, and injuries to arteries may cause bruits (a distinctive sound similar to heart murmurs) to be audible. Percussion of the abdomen may reveal hyperresonance (indicating air in the abdominal cavity) or dullness (indicating a buildup of blood). The abdomen may be distended or tender, signs which indicate an urgent need for surgery.