Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is bibasilar atelectasis , left greater than right . Difficult to exclude underlying pneumonia . The cardiomediastinal silhouette and hilar contours are normal . There are likely a small left pleural effusion . No pneumothorax is identified . Visualized upper abdomen is unremarkable without pneumoperitoneum .
    OUTPUT:
    
Bibasilar atelectasis , can not exclude pneumonia .