Predictive variables influencing intraoperative blood loss during single-stage posterior spinal fusion in severe idiopathic scoliosis: Analysis of 126 cases.

Background: Despite the clinical importance, few studies have specifically addressed intraoperative blood loss in patients with severe idiopathic scoliosis undergoing posterior spinal fusion (PSF). Therefore, this study seeks to investigate independent predictors of intraoperative bleeding during single-stage PSF in this high-risk population. Methods: A retrospective analysis was conducted on 126 patients with severe IS (defined as a major Cobb angle ≥90°) who underwent single-stage PSF without osteotomy procedures. Key parameters collected included preoperative Cobb angle (Pre Cobb), postoperative Cobb angle (Post Cobb), correction rate (CR), side-bending Cobb angle (SB Cobb), side-bending flexibility (SBF), side-bending correction index (SBCI), total number of fusion levels, number of pedicle screws utilized, and operative time (Op Time). The estimated total intraoperative blood loss (EBL) was quantified. Multiple regression analysis was employed to identify independent predictors of intraoperative blood loss. Results: The mean pre Cobb was 103.0 + 12.4° and post Cobb was 45.1 + 14.0°. The mean CR was 56.1 + 12.8 %. The mean SB Cobb and flexibility were 65.0 + 19.4° and 37.7 + 13.7 %. Average SBCI was 1.8 + 1.2. The mean fusion levels and number of screws used were 13.3 + 1.3 and 16.3 + 1.6, respectively. The mean Op time in this study was 185.9 + 49.3 min. The mean EBL was 1493.0 + 841.0 mL, EBL/EBV ratio was 51.6 + 29.1 %, and EBL/level fused was 112.0 ± 62.0 mL. Multiple regression analysis identified Op time, gender, and pre Cobb as the independent predictors for EBL (R2 0.281; p < 0.05). The derived predictive formula was EBL = -1747.0 + (5.6 x Op time) + (13.9 x pre Cobb) + (697.0 x G), where G = 2 for male and G = 1 for female. Conclusions: Operative time, male gender, and preoperative major Cobb angle were the significant predictive factors for EBL in single-stage PSF surgery for severe IS patients.