This prospective observational study aims to evaluate the effect of antegrade pump blood reinfusion using the crystalloid "chase" technique on postoperative transfusion requirements in adult patients undergoing cardiac surgery with cardiopulmonary bypass. At the end of cardiopulmonary bypass, blood remaining within the cardiopulmonary bypass circuit is reinfused antegradely through the arterial line using a crystalloid chase, without collection or storage. Blood remaining within the bypass circuit after surgery represents a valuable source of autologous blood, and its reinfusion may contribute to perioperative blood conservation strategies. Patients receiving antegrade pump blood reinfusion via the chase technique will be compared with those managed without reinfusion, without any intervention by the investigators. The primary outcome is postoperative blood transfusion requirement.

Inclusion Criteria:

• Age 18 to 80 years
• Patients undergoing elective, isolated coronary artery bypass grafting surgery using cardiopulmonary bypass (on-pump).

Exclusion Criteria:

• Emergency or Redo cardiac surgery
• Concomitant cardiac procedures (e.g., valve repair/replacement or aortic surgery).
• Planned or intraoperative conversion to off-pump coronary artery bypass grafting
• Preoperative hematocrit <30% or known inherited/acquired bleeding disorders.
• Preoperative left ventricular ejection fraction <30%.
• Thrombocytopenia (e.g., platelet count <100×10³/µL) or abnormal coagulation tests.
• Use of antiplatelet agents other than aspirin without appropriate discontinuation according to current guideline-recommended preoperative intervals.
• Use of anticoagulant therapy without appropriate preoperative discontinuation according to current guideline recommendations.
• Use of non-steroidal anti-inflammatory drugs (NSAIDs) without appropriate discontinuation prior to surgery.
• Severe renal dysfunction (eGFR <30 mL/min/1.73 m² or dialysis) and/or severe hepatic dysfunction (Child-Pugh B-C or coagulopathy).
• Active infection or systemic inflammatory/autoimmune disease.
• Active malignancy requiring ongoing treatment
• Refusal or inability to provide written informed consent.

The study population includes adult patients (18-80 years) scheduled for elective, primary isolated coronary artery bypass grafting (CABG) using cardiopulmonary bypass at Kocaeli City Hospital.