The impact of major surgery on blood coagulation factors and thrombin generation.

We studied the blood coagulation system of 14 patients with metastatic malignancies before and after they had undergone major surgery. In addition to measuring a battery of coagulation factors, we assessed the function of the system with assays of whole blood thrombin generation. With the exceptions of factor VIII (fVIII), which increased, and fibrinogen and fIX, which did not change, the activities of all the pro- and anticoagulant proteins were significantly lower postoperatively. However, the thrombin generating capacity of the system was relatively preserved. Although the integral of thrombin activity over time was lower after surgery, the mean peak thrombin concentration was unchanged and the time to clot formation was shortened. Similar changes could be reproduced by lowering the concentrations of pro- and anticoagulant factors together in control blood samples. Therefore, simultaneous reductions in pro- and anticoagulant proteins postoperatively worked to maintain the functional integrity of the blood coagulation system.