Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 0 0 2026 05 04 1433 1433 EN Mohammad Shaghaghi Department of Anesthesiology and Critical Care, Al-Zahra Hospital, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. Mehrdad Masoudifar Department of Anesthesiology and Critical Care, Al-Zahra Hospital, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. Mojtaba Rahimi Department of Anesthesiology and Critical Care, Al-Zahra Hospital, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. Maryam Mirhosseini Department of Anesthesiology, Faculty of Medicine, Kerman University of Medical Sciences, Kerman, Iran. 2025 10 05 2025 10 29 Background: Lumbar spinal fusion surgery often involves significant intraoperative blood loss, necessitating packed red blood cell (PRBC) transfusions. While transfusions restore oxygen-carrying capacity, their immediate effects on postoperative hematologic and coagulation parameters remain unclear, potentially confounded by surgical and patient factors. Methods: This retrospective case-control study analyzed 396 adult patients (aged 20–80 years, ASA I–III) undergoing lumbar spinal fusion at Al-Zahra Hospital, Isfahan University of Medical Sciences, from September 2019 to September 2022. Patients were grouped by intraoperative PRBC transfusion status (transfused: n=204; non-transfused: n=192). Primary outcomes were postoperative day-1 hemoglobin (Hb), hematocrit (Hct), international normalized ratio (INR), and prothrombin time (PT). Unadjusted comparisons used t-tests or Mann-Whitney U tests with Benjamini-Hochberg correction. Multivariable regression controlled for age, sex, surgical duration, fusion levels, blood loss, and comorbidities. Results: The unadjusted analysis indicated that transfused patients exhibited significantly decreased hemoglobin (12.0 ± 2.1 vs. 13.5 ± 1.7 g/dL, p < 0.001) and hematocrit (36.1 ± 5.3% vs. 39.7 ± 4.3%, p < 0.001), as well as elevated INR and prolonged PT (p < 0.05). Nonetheless, following multivariable correction for surgery length, blood loss, and comorbidities, only the decrease in Hct retained statistical significance (\beta = -3.63, p < 0.001). The relationships between transfusion and Hb (p = 0.063), INR (p = 0.312), and PT (p = 0.481) were rendered non-significant after adjusting for clinical covariates. Conclusion: Our findings suggest that intraoperative PRBC transfusion does not independently influence early postoperative hematologic or coagulation metrics when accounting for surgical complexity. A slight decrease in hematocrit was seen; however, its clinical significance is negligible. These findings support the safety of restricting transfusion operations, allowing physicians to minimize excessive blood exposure while maintaining hemodynamic stability in spinal fusion patients. https://aacc.tums.ac.ir/index.php/aacc/article/view/1433