A randomized controlled trial for validity of aspirin continuation in the preoperative period of intra-peritoneal surgery

INTERVENTION: aspirin continuation withdraw aspirin (alternative heparin) CONDITION: The patients who need gastroenterological surgery and were treated with prophylactic aspirin due to cardiovascular events PRIMARY OUTCOME: operative blood loss SECONDARY OUTCOME: Adverse events with peri‐operative hemorrhage, transfusion rate, re‐operation rate, hospital stay, cardio‐vasuluar/cardio‐cerebrovascular events, delta hemoglobin INCLUSION CRITERIA: (1) open‐ or laparoscopic‐ cholecystectomy, gastorectomy, or colo‐rectal surgery. (2) more than 3 months aspirin use (3) PS 0‐2 (4) written informed consent