Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Compared the prior study , lung volumes are low . There is increased opacity at the left lung base consistent with a combination of pleural effusion and atelectasis . This has increased slightly when compared the prior study . Superimposed infection can not be excluded . There is unchanged moderate cardiomegaly with mild prominence of the pulmonary vasculature consistent with mild pulmonary vascular congestion .
    OUTPUT:
    
Interval increase in the left - sided pleural effusion with associated atelectasis . Superimposed infection can not be excluded .