Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a small to moderate persistent left pleural effusion , smaller when compared to previous exam . Elsewhere , the lungs are clear . The cardiomediastinal silhouette is within normal limits . No acute osseous abnormalities . Anterior cervical fixation hardware is partially visualized as well as an IVC filter in the abdomen .
    OUTPUT:
    
Persistent but smaller left pleural effusion . No superimposed acute cardiopulmonary process .