Postoperative changes in procoagulant factors after major surgery.

Surgical patients are primarily at an increased risk of perioperative bleeding; however, after surgery, these patients develop hypercoagulability that favors thrombotic events. Currently, the time course of postoperative coagulation is not well characterized. Thus, the aim of the present study was to provide a detailed description of the changes in procoagulant factors in patients after major surgery and to evaluate coagulation tests based on their ability to detect hypercoagulability. Fifty-one consecutive patients undergoing different types of major surgery were analyzed. Blood samples were taken preoperatively and on postoperative days (PODs) 1, 2, 3, and 6. In addition to prothrombin time (PT) and activated partial thromboplastin time (aPTT), all PT-dependent and aPTT-dependent clotting factors, von Willebrand factor (vWF), and fibrinogen were obtained, and thrombelastometry and multiplate electrode aggregometry (MEA) were performed. On POD 1, the majority of clotting factors, including factors II, VII, X, XI, and XII, showed a significant decrease from baseline. Factors II, X, XI, and XII remained significantly reduced until POD 3. In contrast, starting on POD 2, fibrinogen, factor VIII, and vWF continuously increased. No relevant changes were found for PT or aPTT. Thrombelastometry revealed a continuous increase in clot firmness, and MEA demonstrated an increase in platelet aggregation on POD 6. However, absolute values remained within normal ranges, and only serial measurements showed hypercoagulation. Beginning on POD 2 after major surgery, significant hypercoagulability developed in patients. However, clinically used global coagulation tests and point-of-care devices did not reliably reflect the hypercoagulatory state.