Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-upright radiograph of the chest demonstrates increased opacification of the bilateral bases , which likely represents atelectasis , however superimposed infection can not be excluded . The cardiomediastinal and hilar contours are unremarkable . There is no pneumothorax or pleural effusion .
    OUTPUT:
    
Increased opacification of the bilateral bases , which likely represents atelectasis , however superimposed infection can not be excluded .