Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Bibasilar opacities , left greater than right , likely represent a combination of pleural effusion and atelectasis , however pneumonia could be considered in the appropriate clinical setting . The cardiomediastinal and hilar contours are unremarkable . There is no pneumothorax . Free air beneath the right hemidiaphragm is consistent with recent postoperative status .
    OUTPUT:
    
Bibasilar opacities , left greater than right , likely represent a combination of pleural effusion and atelectasis , however pneumonia could be considered in the appropriate clinical setting .