BACKGROUND AND OBJECTIVES:Spine surgery frequently needs allogeneic blood transfusions to compensate for great blood loss. Autologous blood donations often are indicated to reduce homologous transfusions. In last decades interbody spinal fusion has gained popularity, being frequently performed in many spine procedures. Nevertheless, there are few studies evaluating the risk factors of additional blood transfusions in the postoperative course of degenerative spine surgery and no one concerning patients who underwent interbody fusion. MATERIALS AND METHODS:In 15 consecutive months, in the same Department of Spine Surgery 40 different elective spine surgeries were performed, divided into four groups: laminectomy alone, laminectomy with an instrumented posterolateral fusion, laminectomy with an instrumented posterolateral and interbody fusion, extensive instrumented fusion. All patients surgery-related data were respectively recorded: patient age, gender, diagnosis, preoperative hemoglobin rate, autologous blood availability, number of spinal level decompressed and fused, duration of surgery, type of surgical procedure, duration of hospital stay. These data were statistically analysed to determine whether variables could determine higher risk of blood transfusion. RESULTS:In an univariate analysis of factors influencing the need of blood transfusion, significantly greater risk of blood transfusions was observed in the female, in case of low preoperative Hb rate, longer surgical times, multiple spinal level decompressed or fused and longer duration of hospital stay. Our linear multiple regression modeling showed that patients gender and increased number of levels decompressed and levels surgically fused were significant determinants of need of blood transfusion. CONCLUSIONS:The practical value of this work can be particularly appreciated by those who are used to consider blood predonation. According to our findings blood predonation should preferably be proposed to women supposed to undergo spine instrumented fusion or a more than three levels spine decompression.