A 25-year-old man arrives in the emergency department in respiratory distress following a motor vehicle collision. A chest x-ray shows abdominal viscera in the left thorax. What is the most likely diagnosis?

Blunt trauma is the most common cause of diaphragmatic rupture. Associated injuries are common. In blunt trauma, the left diaphragm is ruptured more frequently than the right. The stomach, spleen, colon, and omentum may enter the left pleural cavity. Diaphragmatic injury without herniation of abdominal contents is difficult to diagnose. Patients may present with symptoms many years after the initial trauma. Early surgery is indicted.