Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Semi-upright portable chest radiograph demonstrates unremarkable mediastinal , hilar and cardiac contours . There is increased density of the left hemithorax compared to yesterday which may indicate layering effusion , however , given degree of increased density finding is concerning for reaccumulating hemothorax . Faint opacities are noted within the left lower lung likely reflect atelectasis though infectious process can not be excluded . Given timeframe from initial trauma , these are unlikely to represent pulmonary contusions . Multiple minimally displaced left - sided rib fractures are identified including a segmental fracture of the posterior sixth rib .
    OUTPUT:
    
Increased density of left hemithorax may represent large layering effusion but is concerning for reaccumulation of known hemothorax .