School ager with Wilms tumor status post left pneumonectomy being surveilled for pulmonary metastases Post-operative CXR AP (above) shows complete opacification of the left hemithorax with an air-fluid level within it. AP (lower left) and lateral (lower right) images from an upper GI exam shows herniation of the fundus of the stomach into the left hemithorax. The diagnosis was post-operative occurrence of a diaphragmatic hernia.