Hemostatic Changes Following Red Blood Cell Transfusion in Critically Ill Patients: A Retrospective Cohort Study

Background/Objectives: Red blood cells actively influence hemostasis by enhancing platelet activation, promoting thrombin generation, and contributing to clot structure. Their transfusion may alter coagulation dynamics, yet conventional tests often miss these effects, highlighting the need for viscoelastic monitoring. Methods: This retrospective single-center study carried out in the intensive care unit analyzed ROTEM, conventional coagulation tests, and CBC data pre-post-single-unit RBC transfusion. Platelet and fibrinogen contributions to clot strength were assessed. Statistical comparisons used the Wilcoxon signed-rank test, with significance set at p < 0.05. Ethical approval was waived. Results: Thirty-five patients were analyzed; ROTEM revealed reduced fibrinogen contribution to clot strength and decreased hyperfibrinolysis post-transfusion. Conventional tests showed minimal changes, except for a significant increase in D-dimer levels. Conclusions: Transfusion of a single RBC in non-bleeding critically ill patients with severe anemia may lead to diminished fibrinogen-based clot architecture or fibrin cross-linking, as well as a decrease in hyperfibrinolysis. Most of the hemostatic effects of RBC transfusion cannot be detected by conventional coagulation tests. The net effect of RBC transfusion remains undetermined and requires further mechanistic studies.