Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lung volumes are low . The heart is normal in size . The mediastinal and hilar contours appear within normal limits . The posterior costophrenic sulci are not well visualized , but there is no clear indication of pleural effusion . There is no pneumothorax . A small - to - moderate quantity of free air is visualized under each hemidiaphragm , but anticipated following very recent abdominal surgery .
    OUTPUT:
    
No evidence of acute disease . Free air , anticipated in the early post - surgical course .