Estimating surgical blood loss: A review of current strategies in various clinical settings.

The estimation of surgical blood loss is routinely performed during and after surgical procedures and has morbidity and mortality implications related to the risk of under- and over-resuscitation. The strategies for estimating surgical blood loss include visual estimation, the gravimetric method, the colorimetric method, formula-based methods, and other techniques (e.g., cell salvage). Currently, visual estimation continues to be the most widely used technique. In addition, unique considerations exist when these techniques are applied to various clinical settings such as massive transfusion, cardiac surgery, and obstetrics. Ultimately, when using estimated surgical blood loss to guide perioperative fluid management and transfusion thresholds, it is also important to mitigate the risks associated with resuscitation by targeting a goal-directed fluid therapy approach by utilizing markers of fluid-responsiveness to optimize stroke volume (cardiac output) and delivery of oxygen.