Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-upright radiograph of the chest demonstrates increased interstitial markings in the bilateral lungs concerning for pulmonary edema . Increased opacification in the retrocardiac region raises concern for atelectasis versus pneumonia . There is a small left - sided pleural effusion . Cardiomediastinal and hilar contours are unchanged . No pneumothorax .
    OUTPUT:
    
1 . Interval increase in interstitial markings raises concern for pulmonary edema . 2 . Retrocardiac opacity is consistent with atelectasis or less likely pneumonia .