Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiomediastinal silhouette and hilar contours are unremarkable . There is a small - to - moderate left subpulmonic effusion with adjacent atelectasis . The left upper lung zone and the right lung are clear . There is no pneumothorax .
    OUTPUT:
    
Small - to - moderate left - sided pleural effusion , new since prior study .