Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A moderate volume of free intraperitoneal air below the diaphragm is attributable to recent surgery . The NG tube can be traced only as far as the lower esophagus and can not be localized with respect to the postoperative esophagointestinal junction . Heart size is within normal limits . Mediastinal and hilar contours are unremarkable . There is no evidence for pulmonary edema , pulmonary consolidation , pleural effusion , or pneumothorax .
    OUTPUT:
    
Unable to localize nasogastric tube with respect to postop anatomy of the distal esophagus . Pneumoperitoneum , presumably postoperative .