Hidden blood loss estimation using perioperative hemoglobin drop: agreement with the Sehat formula

Abstract Background Perioperative hemoglobin drop is widely used as a surrogate marker for blood loss and transfusion risk across surgical disciplines. However, its agreement with dilution-based estimates of hidden blood loss remains insufficiently validated. As both approaches represent indirect estimators rather than a reference standard, this study evaluates agreement rather than validation. Methods This retrospective registry-based study included 828 patients undergoing elective primary tota