Background: Fibrinogen is considered an essential part of the clotting cascade, crucial for the formation of the fibrin polymer. Studies have shown that low levels of fibrinogen are associated with increased blood loss and packed-red blood cells (PRBC) units transfused during surgery. Improving pre-operative fibrinogen levels could potentially reduce blood loss and the consumption of hemoderivatives. In this study, it was analyzed whether pre-operative levels of fibrinogen could predict peri-operative blood loss and PRBC transfusion in total hip replacement surgery (THR).
Methods: A retrospective analysis of hemotherapeutic practice in elective THR performed at our hospital was conducted. Due to lack of data only 82 out of a total of 168 patients were included. Pre-operative fibrinogen and hemoglobin (Hb) levels were correlated with the post-operative hemoglobin in the first 48 hours, the hemoglobin fall (pre-operative hemoglobin minus lowest hemoglobin) and the number of PRBC units transfused. The study also includes characterization of the study population.
Results: Mean age of the patients in this study was 64±13 years-old, with 44,6% females; 8,4% were ASA 1, 67,5% were ASA 2 and 22,9% were ASA 3. Half the cases underwent surgery with neuroaxial techniques. None of the patients had known coagulopathy or thrombocytopenia. Fibrinogen levels were categorized in the following groups:  <200 mg/dL (3,6%), 200-300 mg/dL (37,3%), 300-400 mg/dL (49,4%) and >400  mg/dL (8,4%). The mean Hb fall was 3,74±1,68 g/dL with 50% of the patients needing transfusion with an average of 1,8±1,9 units of PRBC. The statistical analysis was performed using SPSS Statistics 21.0. A positive correlation was found between fibrinogen levels <300 mg/dL and the hemoglobin fall (p=0,022), applying Mann-Whitney test. Also according to these results, older patients (> 65 years-old) (p=0,05) and a higher ASA classification (p=0,002) were associated with lower pre-operative fibrinogen levels.
Conclusion: In THR surgery, a higher fibrinogen threshold might be adequate to reduce peri-operative blood loss. Also older patients or patients with higher ASA physical status classification might be at risk of having lower fibrinogen. Therefore, routine pre-operative dosing of fibrinogen in these patients might be valuable. Implementation of protocols regarding pre-operative blood management can improve outcomes by reducing both blood loss and the need of transfusion.

Pre-operative fibrinogen levels are predictive of blood loss in total hip replacement surgery