Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: In comparison to prior study , the lung volumes are markedly low with resultant bronchovascular crowding . Basilar opacities , particularly retrocardiac , likely represent atelectasis . There is no focal opacity concerning for pneumonia . There is no pneumothorax . Hilar and cardiomediastinal contours are unchanged , accounting for technique . Accounting for low lung volumes , there is no evidence of vascular congestion or pulmonary edema . No pneumothorax . Postoperative changes are seen in the upper abdomen , with a drain in the left upper quadrant and an epidural catheter projecting over the left chest wall .
    OUTPUT:
    
Decrease in lung volumes accounts for all findings seen on chest radiograph . No evidence of pneumonia or pulmonary edema .