Table 5. Characteristics of UROR caused by bleeding (n=53).

Feature	Number
Time after initial surgery (hour), median (IQR)	7.8 (19.0)
Drainage volume before UROR (mL), median (IQR)	1,050.0 (600.0)
Estimated blood loss (mL), median (IQR)	2,100.0 (1,000.0)
Bleeding site, n (%)
Unfound	20 (37.7)
Incision	6 (11.3)
Surgical sites
Raw surface of mediastinal LND	6 (11.3)
Resection margin of lung	5 (9.4)
Raw surface inferior pulmonary ligament	5 (9.4)
Parietal pleura	4 (7.5)
Pulmonary vessels	3 (5.7)
Bronchus stump	3 (5.7)
Congestion of wedge resected lobe	2 (3.8)
Blood transfusion (mL), median [IQR]	1,200 [900]
Stay in ICU, (yes), n (%)	11 (20.8)
Length of stay after UROR (day), median [IQR]	7 [3]

UROR, unplanned return to the operation room; IQR, interquartile range; LND, lymph node dissection; ICU, intensive care unit.