Sarah Bos

125 General discussion 7 The downside of a more liberal dosing regimen is an increase in bleeding risk in patients with an already complex and fragile hemostatic balance.(41,42) Hemostasis in liver transplant and HPB-surgery Not only in liver disease, but also in HPB-surgery and liver transplant surgery changes occur in the hemostatic balance. Since the liver has a pivotal role in hemostasis, it is not surprising that during and after liver surgery (transplantation or partial hepatectomy) hemostatic changes occur. Pre-operative hemostatic changes are also often seen in patients with chronic liver disease.(43) Although conventional diagnostic tests of hemostasis in this population (platelet count, prothrombin time, fibrinogen level) are suggestive of a pre-operative bleeding tendency, it is now widely accepted that these tests do not reflect true hemostatic capacity in this population. These conventional diagnostic tests are also unable to predict bleeding events. Pre-emptive correction of the hemostatic status of the patient therefore does not lead to decreased bleeding events and can even provoke thrombotic complications.(44) Although there is a hypercoagulable profile in patients with chronic liver disease, it is well known that this renewed hemostatic balance is fragile and bleeding complications also still occur. Surgical and anesthesiologic improvements have led to a substantial decrease in blood loss.(45) Management of intraoperative bleeding still needs refinements in order to further decrease blood loss. Peri- operative blood loss is associated with portal hypertension and seems to be more relevant than the hemostatic status of the patient.(46) The increased incidence of VTE after liver surgery indicates amore hypercoagulable profile in this specific patient population.(47–50) Strategies to reduce VTE can still be optimized. Nowadays almost all patients receive pharmacological thromboprophylaxis with LMWH as soon as possible after surgery. There is some rational for a higher dose of postoperative thromboprophylaxis for specific patient populations with increased risk of thrombotic complications such as obesity and cancer. Even in HPB-surgery patients treated with thromboprophylaxis VTE still occurs. Whether a higher dose or an alternative therapy is indicated is unclear and further research on this topic is needed.(47,51) Pro- and anticoagulant therapy in liver transplant and HPB-surgery As described in chapter 5 and 6 there is an increased risk of DVT following HPB-surgery. About 3-9% of the patients develop DVT despite sufficient thromboprophylaxis.(47,49,52–54) In patients after liver transplantation the development of portal vein thrombosis or hepatic artery thrombosis is a direct threat to graft function.(55,56) Given the peri-operative hemostatic changes