Table 4. Additional surgery and procedure-related adverse events (n=5,269).

Events		Values
Adverse events		240 (4.6)
	Intraprocedural bleeding*	8 (0.2)
	Delayed bleeding†	181 (3.4)
	Perforation	46 (0.9)
	Others	5 (0.1)
Additional surgery (indication)		614 (11.7)
	NCR	599 (11.4)
	Complication	5 (0.1)
	Others‡	10 (0.2)

Values are shown as number (%). Data are presented on a per-hospitalization basis, with multiple ESDs during a single hospitalization considered as one ESD session. Percentages were calculated based on the total number of ESD sessions (n=5,269).

NCR = non-curative resection; ESD = endoscopic submucosal dissection.

^*Intraprocedural bleeding was defined as an event requiring transfusion.

^†Delayed bleeding was defined as overt gastrointestinal bleeding, a decrease in hemoglobin of ≥2 g/dL, or the need for transfusion.

^‡Additional surgery was performed in 9 patients classified as curative resection according to guideline-based criteria, based on cautious clinical judgment after discussion with the patient. These included lesions that met the expanded criteria but had potentially unfavorable features, including predominantly undifferentiated histology despite a size of ≤2 cm, lesions >2 cm with a minor undifferentiated component, or shallow submucosal invasion. One patient underwent surgery due to patient preference.