We report a case of bloody pleural effusion and infarction of the greater omentum caused by a non‐traumatic diaphragmatic hernia with a late presentation. A 15‐y‐old boy with Down's syndrome developed abdominal pain and vomiting, as well as an elevated serum level of C‐reactive protein. Chest roentgenograms showed a right‐sided pleural effusion and computed tomography revealed a right diaphragmatic hernia. Barium enema confirmed the diagnosis. An operation revealed a right Bochdalek's hernia with strangulation of the greater omentum in the right pleural cavity.
Conclusion: Diaphragmatic hernia should be considered in patients with pleural effusion, abdominal pain and vomiting.