Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low causing crowding of the central bronchovascular structures . There is possible mild central vascular congestion . The heart is mildly enlarged and stable , and the patient is status post median sternotomy and coronary artery bypass . There is no pleural effusion , pneumothorax or overt pulmonary edema . The patient is status post cholecystectomy . No displaced rib fractures are seen .
    OUTPUT:
    
No definite rib fractures or pneumothorax . If there is further concern for rib fracture dedicated rib series may be performed .