Development and validation of a novel tool to estimate peri‐operative blood loss*

Surgical blood loss predicts peri-operative outcomes. We have developed and validated Blood Loss Scores to estimate peri-operative blood loss during major abdominal surgery. Surgical blood loss and changes in haemoglobin concentration were recorded intra- and postoperatively for 48 h in 100 patients undergoing radical prostatectomy. Data from the first group (n = 50) were used to derive the Blood Loss Scores which were validated against the data from a second group (n = 50) at three time points (immediately postoperative and 24- and 48-h later). The score, taking into account suction fluid volume and haemoglobin concentration, explained more of the variance in the measured blood loss than the experts' assessment (77% vs 54%, p = 0.05) or the change in haemoglobin concentration (77% vs 11%, p < 0.0001). Addition of the change in haemoglobin concentration improved the estimate for the 24- and 48-h postoperative Blood Loss Scores to explain 78% and 80% of the variance of measured blood loss.