[Visual estimation of blood losses : Known high error rate-How can it be improved?]

Every day blood losses are visually estimated by medical personnel (physicians, midwives, paramedics) because an exact quantitative measurement is impossible or impractical. Anesthesiologists are confronted with blood loss in the operating room, in the delivery room, in the emergency room and at the scene of an emergency; however, the literature shows that in all the named areas enormous errors occur in the visual estimation. Errors of 50% and more are not uncommon, which means that, e.g., an estimated blood loss of 2000ml could actually be 3000ml or only 1000ml. General, in all the abovenamed areas blood losses are more likely to be underestimated than overestimated. The ability to make an estimation is not improved by professional experience. The amount of blood loss indicates and "justifies" invasive measures and the administration of blood and cost-intensive blood products. This overview is dedicated to the problems in the estimation of blood loss, demonstrates the sequelae of an incorrectly estimated blood loss, provides tips on how the ability to make an estimation can be improved and describes the considerable potential of further education as well as which digital support options are now available.