Massive transfusion is defined as:

However, in obstetric settings, blood loss may be unpredictable, sudden, and severe. A patient can lose a significant portion of her blood volume in a matter of minutes, and symptoms of hypovolemia may not present until 25% of blood volume (1.5 L in term pregnancies) is lost (2). Therefore, the standard definition for massive transfusion may not be adequate in identifying patients at risk for, or in need of, massive transfusion in this setting. Recognition of postpartum hemorrhage, before deterioration in vital signs, is crucial to improve maternal morbidity and mortality (3).

The risk for massive transfusion is, as expected, highest around the time of delivery and is especially prevalent in the postpartum period. In fact, postpartum hemorrhage continues to be a leading cause of maternal mortality in the United States (3).

Owing to the increase in blood volume during pregnancy, using hemoglobin or hematocrit as a sole maker to assess acute
obstetric blood loss is likely inadequate; therefore, careful monitoring for clinical signs and symptoms of anemia is essential.

A normal adult can tolerate a 10% to 15% acute loss in blood volume. However, once blood loss is >40%, physiologic changes can be observed and measured. In obstetric settings, acute blood loss can be devastating to fetal well-being. In addition, a pregnant patient’s lungs, kidneys, and anterior pituitary gland are particularly at risk (5).

Once these changes are observed, the need for RBC transfusion is imperative to prevent the patient from developing hypovolemic shock. Owing to the acute and severe nature of obstetric bleeding, the volume of RBCs required to improve physiologic changes is often high.

Traditionally, resuscitation for hypovolemia caused by hemorrhage started with the infusion of crystalloids and RBCs. However, evidence suggests that aggressive “hemostatic” resuscitation, using blood products including plasma and platelets, can lead to improved outcomes in the setting of massive hemorrhage (6). High-volume isolated RBC or excessive crystalloid resuscitation can result in dilutional coagulopathy and/or thrombocytopenia in which the patient’s coagulation proteins and platelets become significantly diluted. Particular attention should be paid to fibrinogen, which is a positive predictor for severe postpartum hemorrhage when levels fall below 200 mg/dL (7).

Massive transfusion protocol (MTP) is designed to address events where large-volume transfusions are required. The primary goal is the early administration of blood products. MTPs were designed specifically for trauma settings. However, over time, institutions have developed protocols for other settings including obstetrical hemorrhage. In obstetrical patients, special consideration should be given to address the need for fibrinogen early in resuscitation, in addition to choosing the blood components necessary to prevent and/or correct dilutional coagulopathy and thrombocytopenia. MTPs are designed to issue blood components in predetermined ratios until deactivation or transition to goal-directed resuscitation can be performed.

MTP development for obstetrical patients should involve a multidisciplinary team including obstetrics, anesthesia, transfusion medicine/blood bank, nursing, and surgical personnel.