B Bleeding associated with signs or symptoms of hypovolemia within 24 hours of delivery
Explanation:
Up to 3% of all deliveries in the United States are complicated by postpartum hemorrhage; of these, more than half require blood transfusion. The most common cause of postpartum hemorrhage is uterine atony (when the uterus does not effectively contract after placental delivery), but it can also be due to uterine trauma, abnormal placentation, or coagulopathy. In 2017, the American College of Obstetricians and Gynecologists (ACOG) updated the diagnostic criteria for postpartum hemorrhage. The diagnostic criteria is cumulative blood loss ≥ 1 000 mL regardless of mode of delivery or bleeding associated with signs or symptoms of hypovolemia within 24 hours of delivery. Thus, though she does not meet the estimated blood loss threshold for postpartum hemorrhage, she qualifies due to her pale appearance, hypotension, and tachycardia. Prior to 2017, ACOG defined postpartum hemorrhage by an estimated blood loss ≥ 500 mL after vaginal delivery or ≥ 1 000 mL after cesarean delivery. This diagnostic threshold was problematic for multiple reasons: the mean estimated blood loss after vaginal delivery is 400 to 600 mL and after cesarean delivery is 1 000 mL. Also, maternal blood is often mixed with amniotic fluid at delivery (falsely increasing the subjectively or objectively reported estimated blood loss). The new criteria were created to decrease the rate of false diagnoses of postpartum hemorrhage.