The concept that patients with stable liver disease are at an increased risk of bleeding, based solely on abnormalities of conventional coagulation tests such as prothrombin time (PT) and international normalized ratio (INR), is now recognized to be an overly simplistic interpretation of an extremely complex situation. These tests are in fact very poor predictors of bleeding in patients with liver disease who undergo invasive or surgical procedures. Commercially available whole blood viscoelastic tests (thromboelastography [TEG] and thromboelastometry [ROTEM]) evaluate the kinetics of coagulation from initial clot formation to final clot strength. These dynamic tests provide a composite picture reflecting the interaction of plasma, blood cells, and platelets, and more closely reflect the situation in vivo than do PT/INR, which are performed on plasma samples and measure isolated end points. Despite prolonged PT/INR and low platelet counts, viscoelastic tests are within normal range in many patients with both acute and chronic liver disease, commensurate with the concept of rebalanced hemostasis, and in keeping with the fact that an increasing number of these patients undergo liver transplantation without the need for blood or blood products. In addition, these tests reveal important additional information, such as the presence of hypercoagulability and a prothrombotic state, and also information about the presence of endogenous heparinoids associated with vascular endothelial damage, due to sepsis or acute inflammation. This review provides an overview of the current literature on the potential clinical utility of viscoelastic tests of coagulation in patients with liver disease.
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.