Bochdalek hernia masquerading as a tension pneumothorax.

A rare case of congenital diaphragmatic defect presenting with clinical signs of an acute tension pneumothorax is described. The clinical findings were eventually attributable to a herniation of abdominal contents into the chest (Bochdalek hernia). Attempted decompression of the chest by needle thoracocentesis and subsequent introduction of a chest drain caused gastric perforation, requiring repair at laparotomy. It is suggested that if needle thoracocentesis does not result in immediate clinical improvement, or if there is abdominal pain, a portable chest radiograph should be performed before tube thoracostomy to exclude Bochdalek hernia. All emergency department staff should be taught to recognise the radiological appearance of a Bochdalek hernia.