Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Since the prior exam performed after the earlier thoracentesis , there appears to have been a slight increase in the residual left pleural effusion . It remains small in size . Again , some left basilar atelectasis persists . There are persistent fibrotic changes at the bases . No pneumothorax is identified . The cardiomediastinal silhouette is normal .
    OUTPUT:
    
Very slight interval increase in the size of the small residual left pleural effusion . No evidence of pneumothorax .