Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Since the prior study , there is now opacity at the right lung base worrisome for right middle lobe atelectasis . Small right pleural effusion was also seen on pre seeding chest CT . The left lung is clear . No overt pulmonary edema is seen . Cardiac and mediastinal contours are grossly stable . No pneumothorax is seen .
    OUTPUT:
    
Interval volume loss of the right lung and right mid to lower lung atelectasis . Given short term development , findings could be due to mucous plugging / aspiration obstructing the airway .