Risk Factors of Total Blood Loss and Hidden Blood Loss in Patients with Adolescent Idiopathic Scoliosis: A Retrospective Study

Objectives. To investigate the risk factors of total blood loss (TBL) and hidden blood loss (HBL) in adolescent idiopathic scoliosis (AIS) patients undergoing posterior orthopedic surgery. Methods. The AIS patients who visited department of spine surgery between January 2015 and December 2020 were retrospectively reviewed. Those with a history of posterior orthopedic surgery for AIS were identified, and their clinical data were collected. Gross formula was used to calculate the TBL and HBL. SPSS 20.0 was used for statistical analysis. The potential risk factors of TBL and HBL were assessed by independent t-test or univariate analysis. The risk factors of TBL and HBL were determined by multiple linear regression. Results. A total of 114 patients were included in this study. Operative time (P < 0.001), postoperative platelets (PLT) (P=0.001), the number of surgical fixation segments (P < 0.001), implanted screws (P < 0.001), hospital stay (P=0.006), type of scoliosis (P < 0.001), and correction angle of scoliosis (P=0.063) were the potential risk factors of TBL. Operative time (P < 0.000), postoperative PLT (P=0.095), the number of surgical fixation segments (P < 0.001), implanted screws (P < 0.001), type of scoliosis (P < 0.001), correction angle of scoliosis (P=0.073), and total blood volume (P=0.098) were the potential risk factors of HBL. Multiple linear regression analysis showed that operative time (P=0.003) and the number of surgical fixation segments (P=0.014) were risk factors of TBL, while the number of surgical fixation segments (P=0.004) was a risk factor of HBL. Conclusions. In AIS patients undergoing posterior internal fixation surgery, the operative time and the number of surgical fixation segments are risk factors of TBL, and the number of surgical fixation segments is a risk factor of HBL. Surgeons need to consider these factors when making surgical strategies for AIS patients.