[Not Available].

INTRODUCTION AND AIM: Minimally invasive surgery (MIS) of the spine prevents the collapse of osteoporotic vertebral fractures (OVF) with lower complication and bleeding rates than open surgery. However, the possibility of hidden blood loss (HBL) has been recently described, referring to the loss of blood diffused into tissues and lost through hemolysis. This study aimed to estimate the postoperative impact of HBL in patients undergoing MIS for OVF.

MATERIALS AND METHODS: This was a retrospective study of a series of patients who had MIS for OVF. A descriptive analysis of recorded variables was performed, and total blood volume (VST), total bleeding (TB), HBL, and Hb drop were calculated. This was followed by a comparative analysis between HBL (<500 mL vs. ≥500 mL) and the variables of hospital stay and postoperative evolution. Binary logistic regression models were performed to rule out confounding factors.

RESULTS: A total of 40 patients were included, 8 men and 32 women, with a mean age of 76.6 years. The mean HBL was 682.5 mL. An HBL greater than 500 mL is found to be an independent risk factor for torpid postoperative evolution (p = 0.035), while it does not predict a longer hospital stay (p = 0.116). In addition, a higher HBL was observed in surgeries of greater technical complexity and longer surgical time.

CONCLUSIONS: Although MIS techniques have shown less intraoperative bleeding than open surgery, HBL should be diagnosed because it is associated with a torpid evolution. The use of a diagnostic and therapeutic algorithm may help minimize its impact.