Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral chest radiographs . Small left pleural effusion is new with associated atelectasis . The right lung is clear . There is no pneumothorax . The cardiomediastinal silhouette is normal . Subtle air fluid levels in the upper abdomen are non-specific .
    OUTPUT:
    
New small left pleural effusion . Underlying pneumonia can not be excluded .