Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a moderate left pleural effusion with persistent left lower lobe atelectasis . The degree of aeration is similar when compared to the prior study . Airspace opacity in the left lower lobe may be due to re-expansion pulmonary edema or residual a atelectasis . No pneumothorax seen . The right lung is grossly clear .
    OUTPUT:
    
Moderate size left pleural effusion . Airspace opacity in the left lung base may reflect atelectasis , re-expansion pulmonary edema or infection .