Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest were reviewed . Compared to the most recent prior radiograph , there is a new large left pleural effusion . The right lung is clear without pleural effusion , pulmonary edema , or vascular congestion . There is no pneumothorax . The large pleural effusion obscures the cardiac and mediastinal contours , but presumably they are unchanged .
    OUTPUT:
    
Large left pleural effusion is new since ___ .