Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A focal convexity of the left mediastinal contour in the region of the aorticopulmonary window is stable in the postoperative period , but new compared to preoperative radiographs prior to the patient 's coronary bypass surgery procedure . Moderate - sized left pleural effusion is a persistent postoperative finding , accompanied by adjacent left lower lobe atelectasis . Right lung is grossly clear , but small pleural effusion is again demonstrated posteriorly .
    OUTPUT:
    
1 . Persistent postoperative left mediastinal widening in aorticopulmonary window , which may be due to a postoperative hematoma or loculated fluid collection . 2 . Persistent moderate left pleural effusion and adjacent left lower lobe atelectasis . Unchanged small right effusion .