Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There are persistent small bilateral pleural effusions . Retrocardiac opacity could be secondary to atelectasis . The lungs are otherwise clear . There is no edema . Mild cardiac enlargement is accentuated by low lung volumes but similar to prior . No acute osseous abnormalities .
    OUTPUT:
    
Persistent small bilateral pleural effusions . Associated left basilar opacity which may be atelectasis although superimposed infection can not be excluded .