Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Compared to the prior study there has been a slight increase in the left pleural effusion with fluid extending into the left major fissure . Left lower lobe atelectasis is similar in extent , ca n't exclude superimposed infection . No other areas concerning for lower per consolidation are seen . Visualized bony structures have a somewhat mottled appearance , better demonstrated on the prior CT . .
    OUTPUT:
    
Slight interval increase in the left - sided pleural effusion .