['Patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) are at risk of bleeding. The goal of this investigation was to compare thromboelastography (TEG) with standard coagulation tests (prothrombin time [PT], partial thromboplastin time [PTT], fibrinogen, and D-dimer) in patients with active bleeding.', 'A retrospective study of patients who underwent cardiac surgery with CPB was performed. A second analysis was performed to determine if a shortened TEG R time is associated with thrombosis.', 'Paired TEG and standard coagulation tests were available from 21 bleeding patients; of the 15 patients with normal TEG values and three with a shortened R time, all had abnormalities of standard coagulation tests. Eighteen of 67 patients who underwent surgery with CPB had an episode of postoperative bleeding. The TEG R time and coagulation index, PT, and PTT collected after CPB were associated with postoperative bleeding in the univariate analysis, but only PT was independently associated with postoperative bleeding in the multivariate analysis. In the second analysis, three of 38 patients with a normal TEG and four of 43 patients with a shortened R time had a thrombotic event during hospitalization (P = 1.00).'] Is thromboelastography a suboptimal test for determination of the underlying cause of bleeding associated with cardiopulmonary bypass and may not predict a hypercoagulable state?