Figure 2 Perioperative chest X-ray evolution (all images are bedside anteroposterior supine views). (A) Preoperative (baseline): Both lung fields are symmetrically lucent with clearly visible vascular markings. No pleural effusion, pneumothorax, or subcutaneous/mediastinal emphysema are present; The cardiac silhouette and mediastinum are centrally positioned. The diaphragmatic contours are smooth and the costophrenic angles are sharp. No significant thoracic or pulmonary abnormality was noted preoperatively, providing a baseline for postoperative comparison. (B) The first day after the first operation: A large, homogeneous, high-density opacity occupies almost the entire right mid- and lower-hemithorax, indicating massive hemothorax or active intrathoracic bleeding. The right lung is markedly volume-reduced, consistent with passive atelectasis. The mediastinum is slightly shifted to the left. No distinct air-fluid level is seen, suggesting the presence of clotted or fresh blood rather than free fluid. Imaging findings are compatible with acute postoperative hemothorax, and re-exploration is warranted. (C) The first day after the second operation (with gauze packing): The right hemithorax shows diffuse, dense opacification that is more extensive than in panel B, reflecting combined effects of gauze packing and residual blood resulting in complete right lung atelectasis (“white-out”). The mediastinum and trachea are further displaced to the left. The right hemidiaphragm is markedly elevated, indicating significant mass effect. There is still no evidence of pneumothorax or subcutaneous emphysema. The gauze packing has achieved hemostasis, but the chest radiograph now displays a “white lung;” therefore, close monitoring for re-expansion is required. (D) The eighth day after the first operation (gauze removed): Lucency has returned to the right hemithorax, with near-complete re-expansion of the lung. Only faint linear opacities remain, consistent with resolving residual blood or exudate. No pneumothorax, pleural effusion, or subcutaneous/mediastinal emphysema was detected. The mediastinum and diaphragm have returned to midline positions, indicating complete resolution of mass effect. After gauze removal, the lung has re-expanded well and pleural drainage is adequate. The radiographic appearance has nearly returned to the preoperative baseline.