Sarah Bos

73 Hemostatic complications in hepatobiliary surgery 5 Liver Transplantation Thrombotic events occurring after liver transplantation can be divided into local hepatic vessel thrombosis (Fig. 1) and systemic thrombotic complications. Hepatic vessel thrombosis poses a threat to both patient and graft survival. The incidence of hepatic artery thrombosis (HAT) is approximately 3 to 7%.(72–75) HAT may occur early (within 2–3 months) after transplantation, but may also occur years after the procedure.(75) Early HAT may result in necrosis of the bile ducts and eventually graft loss if the arterial flow is not restored in time.(73) In comparison with early HAT, late HAT might not be life threatening or even have clinical consequences because of the formation of collateral arterial circulation before total obstruction. (73) Preoperative hyper- coagulability, assessed by thromboelastography, has been shown to indicate an increased risk for postoperative HAT.(76) In addition, it has been shown that preoperative PVT is a risk factor for development of postoperative HAT, again suggesting that a relative hypercoagulable state predisposes to HAT.(77) PVT complicates around 2 to 3.1% of liver transplantations.(7,72,78) Notably, the incidence of preexisting PVT discovered during surgery is considerably higher, 4.9 to 14%, with an even higher incidence in specific subgroups, such as patients with a malignancy.(7,79) The risk of PVT after liver transplantation is related to technical difficulties during surgery, prior PVT, a pediatric recipient, splenectomy, the use of venous conduits, and small portal vein size.(54) Early postoperative PVT can cause acute clinical deterioration because of ischemia, ascites, and increased portal vein pressure.(7,54) Early PVT is associated with an increased mortality compared with liver transplant recipients who do not develop a PVT.(8,72) Systemic thrombotic complications may occur in the perioperative period, but also years after transplantation. Recently, several cohort studies have reported on the overall incidence of VTE after liver transplantation. These reports showed incidences varying between 4.5 and 8.6%.(80–84) Notably, the study that reported an incidence of 8.6% only considered the number of deep vein thrombosis,(82) an even higher incidence would likely have been found if pulmonary embolisms had been taken into account. Importantly, none of the patients in this study received pharmacological thromboprophylaxis. Although less common, intraoperative thrombosis is of significant relevance due to the association with an increased morbidity and mortality.(45) Intraoperatively, acute intracardiac thrombosis or pulmonary embolism may occur, with an estimated incidence between 0.4 and 6.2%.(85–87) These complications are potentially fatal and appear to be more frequent in liver transplant recipients than in other surgical patients.(88) As previously argued; the current literature shows that a large proportion of the patients undergoing liver transplantation