Measured versus Estimated Blood Loss: Interim Analysis of a Prospective Quality Improvement Study.

Estimated blood loss (EBL) is an increasingly important factor used to predict outcomes, such as morbidity and mortality, length of stay, and readmissions, after major abdominal operations. However, blood loss is difficult to estimate, with frequent under- and overestimations, consequences of which can be potentially dangerous for individual patients and confounding for scoring systems relying on EBL. We hypothesized that EBL is often inaccurate and have prospectively enrolled consecutive patients undergoing major elective intra-abdominal operations. Actual hemoglobin levels were measured and used to calculate the measured blood loss (MBL), which was compared with the EBL, as estimated both by surgeons (sEBL) and anesthesiologists (aEBL). Of 23 eligible cases at interim analysis, pancreaticoduodenectomy (n = 8) was the most common, followed by colectomy (n = 3), hepatectomy (n = 3) and gastrectomy (n = 2), biliary excision and reconstruction (n = 2), combined gastrectomy 1 colectomy (n = 1), radical nephrectomy (n = 1), open cholecystectomy (n = 1), pancreatic debridement (n = 1), and exploratory laparotomy (n = 1). aEBL overestimated MBL by 192 mL (143%) on average. The aEBL was significantly greater than the MBL (P = 0.004), whereas the sEBL was significantly less than the MBL (P = 0.009). In conclusion, surgeons significantly underestimate and anesthesiologists significantly overestimate EBL. This finding impacts not only immediate patient care but also the interpretation of scoring systems relying on EBL.