It is estimated that, worldwide, 140,000 women die I ofpostpartum hemorrhage (PPH)each year—1 every 4 minutes. More than half of all maternal deaths occur within 24 hours of delivery, most commonly from excessive bleeding. In addition to death, serious morbid-ity may follow postpartum hemorrhage. Sequelae include adult respiratory distress syndrome, coagulopathy, shock, loss of fertil-ity, and pituitary necrosis (Sheehan syndrome).
Hemorrhage can be sudden and profuse, or blood loss can occur more insidiously. PPH has been tradition-ally defined as a delivery-associated blood loss in excess of 500 mL for vaginal delivery and 1000 mL for cesarean birth; however, these estimates actually represent the aver-age blood loss for each mode of delivery, respectively. The estimation of blood loss is subjective, introducing wide variance and inaccuracy.
Additionally, the same absolute volume loss for a patient weighing 50 kg may have vastly different effects than it would for someone weighing 75 kg, or for a patient with triplets versus a singleton. Thus, it is likely more appropriate and meaningful to use physiologic and objec-tive criteria in defining clinical hemorrhage. Criteria in use include a 10% drop in hematocrit, need for trans-fusion, and signs and symptoms along the spectrum of physiologic effects of blood loss, described below.