Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There has been interval placement of a left - sided chest drain with the pigtail formed over the expected region of the pleural space . There is no pneumothorax . There is marked improvement in the left pleural effusion with improved but persisting residual retrocardiac atelectasis . Otherwise , the cardiomediastinal contours appear normal . A right - sided PICC tip terminates in the SVC .
    OUTPUT:
    
Status post left pleural pigtail catheter placement with improved left pleural effusion and no pneumothorax ; persisting residual retrocardiac atelectasis .