Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable upright chest radiograph ___ at 09 :57 is submitted .
    OUTPUT:
    
Status post median sternotomy with stable cardiac and mediastinal postoperative contours . Persistent layering small effusions , left greater than right . Retrocardiac consolidation favoring lower lobe atelectasis , although pneumonia or aspiration should also be considered . Probable mild perihilar edema . No pneumothorax .