Factors Affecting Intraoperative Blood Loss in Scoliosis Surgery: An Observational Cross-sectional Study

Introduction: Significant intraoperative blood loss may be associated with scoliosis surgery. To know about the quantity of blood loss and risk factors associated is imperative in limiting the blood loss as well as to plan transfusion strategies like blood conservation techniques.

Aim: To evaluate the quantity of intraoperative blood loss in scoliosis surgery and to study the various factors contributing to blood loss.

Materials and Methods: This was a cross-sectional prospective observational study conducted at Government Medical College, Thiruvananthapuram, India, from January 2019 to January 2020. Thirty-five (ASA I and II) consecutive patients were scheduled to undergo surgery for correction of scoliosis, and consecutive sampling was done. Age, gender, weight, height and body mass index were noted. During surgery, intraoperative blood loss was measured by gravimetric method from the suction drain and by numerically assessing the quality of the surgical field by the operating surgeon using fromme’s ordinal scale. All these data were entered into structured proforma and analysed by using Statistical Package for Social Sciences (SPSS) version 21.0.

Results: The mean age of subjects was 13.69±1.43 years. The mean intraoperative blood loss was 645.60±143.26 mL {20.11±11.7 % of Estimated blood volume (EBV)}. Mean duration of surgery (r=0.890, p<0.001),Cobb’s angle (r=0.829, p<0.001), number of fused vertebra (r=0.694, p<0.001) correlated with intraoperative blood loss, expressed as a percentage of EBV. The quality of the surgical field, using Fromme’s ordinal scale by visual assessment, correlated with the mean intraoperative blood loss (p=0.001).

Conclusion: Duration of surgery, number of fused vertebrae, and preoperative cobb’s angle are the most important factors predicting intraoperative blood loss in patients undergoing scoliosis surgery.