Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is no evidence of a pneumothorax . Atelectatic changes are seen at the left lung base in the setting of increased stomach distention and elevation of the left hemidiaphragm . Pneumonia can not be excluded in the left lung . The right lung is clear . No other changes are seen compared to prior exam .
    OUTPUT:
    
No evidence of pneumothorax . Increased distention of the stomach and atelectasis of the left lung makes it difficult to exclude a pneumonia .