Introduction and Objectives: Bleeding during lumbar surgery requires the use of blood products for its management. Autotransfusions are an alternative to blood transfusions, since these are not free of risk. Although autotransfusion is a very effective technique, its efficiency is conditioned by its high cost and the fact that a large number of autodonations have to be destroyed when the patients do not require them during the postoperative period. We wanted to discover the factors that determine the use of blood products during the postoperative period so as to obtain blood autodonations from these patients.

Materials and Methods: We carried out a retrospective study of 143 patients that underwent surgery for degenerative conditions of the lumbar spine. We assessed different variables: Age, sex, lumbar level operated on, operation time, pre and postoperative hemoglobin and associated conditions (Charlson comorbidity index and ASA scale).

Results: We found a significant statistic correlation with female sex, age over 60, ASA 3, preoperative hemoglobin < 136 gr/l. Using logistic regression we found that the combination woman, ASA 3 was the most important prognostic factor with a specificity above 90%. We also found that the possibility of requiring a transfusion in a woman/ASA 3, was 61% and at the other end of the spectrum 1.1% in a man/ASA< 3,

Discussion and Conclusions: If we plan an autotransfusion in a woman with ASA 3, there is a probability of 61% that she will require a transfusion with specificity greater than 90%.