Abstract
BACKGROUND: Hidden blood loss (HBL) is often ignored unilateral biportal endoscopic interbody fusion surgery (ULIF). We investigated the amount and influencing factors of HBL in ULIF surgery in this study. METHODS: From October 2020 to November 2023, 100 patients' clinical and radiological data were retrospectively analyzed. Pearson or Spearman correlation and multivariate linear regression were used to identify factors linked to HBL. RESULTS: The mean hidden blood loss (HBL) was 255.84 ± 290.89 ml, making up 62.48% of total blood loss. Correlation analysis showed HBL positively related to ASA classification (P = 0.009), operation time (P = 0.004), number of operation levels (P = 0.046), and paraspinal muscle thickness (P = 0.043), but negatively related to tranexamic acid use (P = 0.001). A multivariate linear regression analysis showed that HBL was positively associated with ASA classification (P = 0.038) and operation time (P = 0.046), but negatively associated with tranexamic acid use (P = 0.001). CONCLUSION: Patients undergoing ULIF surgery incurred a great deal of HBL. More importantly, ASA classification, operation time and tranexamic acid use were independent risk factors for HBL.