Accuracy of Blood Loss Estimation After Vaginal Delivery

Post-partum hemorrhage (PPH) is defined as blood loss greater than 500 mL after vaginal delivery. Delayed diagnosis of PPH is a major cause of maternal morbidity and mortality. Obstetricians estimate blood loss at delivery by visual estimation of blood collected in the obstetric drapes. Blood is often mixed with urine and surgical sponges. The urine, blood, and sponges collect in a cone shaped plastic bag that is suspended from the perineum during delivery. Visual estimation of blood loss is insensitive in diagnosing PPH. In one study visual assessment of blood loss underestimated postpartum blood loss by 33% to 50% compared to an objective measurement of blood loss using photospectrometry. Other studies have shown that the magnitude of underestimation increases as the amount of blood loss is increased. A limitation of previous studies is that there is no "gold standard" for blood loss determination in the third stage of labor. Care providers (obstetricians, anesthesiologists, and labor & delivery nurses) need to be able to accurately estimate blood loss in order to better care for mothers and prevent morbidity and mortality. It is unknown whether provider type or experience (obstetric and anesthesiology resident, fellow, attending physicians, and nurses) influences the accuracy of blood loss estimation, or whether blood loss estimation can be improved by providing graduated markings on the vaginal delivery drape.