A previously healthy 26-year-old man presented with the chief complaint of acute onset left-sided pleuritic type of chest pain. On enquiry he gave a history of blunt trauma to the lower chest and the abdomen due to a fall 6 years earlier which had been managed conservatively. On examination, the patient was obviously distressed and had tachycardia and tachypnoea. Breath sounds were absent in the left infrascapular and infra-axillary regions. His haematological and biochemical parameters were within normal limits. Arterial blood gases revealed hypoxaemia with PaO2 66 mmHg, PaCO2 36 mmHg, pH 7.41. Chest X-ray and computed tomography (CT) scans are shown in figures1-3. 1 : What is the differential diagnosis of the chest X-ray ? 2 : What do the CT scans show? ### QUESTION 1 The chest X-ray shows an apparent elevation of the left hemidiaphragm with a large gas collection below it. The diagnostic considerations include eventration or paralysis of the diaphragm and diaphragmatic hernia. ### QUESTION 2 On a chest X-ray it may be difficult to determine whether an abdominal organ lying unusually high is located beneath an elevated hemidiaphragm (in conditions like eventration or paralysis of hemidiaphragm) or is herniating through a deficit in the diaphragm.1 In this case a diagnosis of herniation can be easily made on the basis of the CT scans, which show …