Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-upright radiograph of the chest demonstrates low lung volumes with resultant bronchovascular crowding . Again seen is moderate postoperative atelectasis in the retrocardiac region , which is unchanged , as well as a persistent small left - sided pleural effusion . The cardiomediastinal and hilar contours are unchanged . There is no pneumothorax .
    OUTPUT:
    
Persistent small left - sided pleural effusion and adjacent atelectasis .