Unexpected Coagulation in the Bypass Pump Circuit

We present a case of premature coagulation in the bypass pump circuit. Fiftynine years-old female (Euroscore: 5) presented with acute heart failure and pulmonary edema due to mitral valve stenosis. Following one vessel coronary bypass and mitral valve replacement (cross clamp time: 170 minutes), the blood collected before heparinization had to be transfused due to persistent bleeding. A short while after the transfusion, we had to initiate the backup bypass machine due to coagulation in the pump circuit. We are in the opinion that the whole blood with fresh coagulation factors activated the intrinsic pathway in the pump circuit and caused the coagulation.