A review of new research on maternal hemorrhage

June 1, 2012

A look at new research on one of the leading causes for maternal mortality.

Key Points

Worldwide, hemorrhage is the most common cause of maternal mortality and the third leading cause in the United States of maternal deaths resulting from direct obstetric factors.1 Early recognition and aggressive treatment of obstetric hemorrhage are of paramount importance and most often lead to improved maternal outcomes. Recent trauma and intensive-care literature has questioned the classic understanding of acute coagulopathy and suggests novel therapeutic interventions for management of massive hemorrhage. Although most of these studies are based on limited data in nonobstetric populations, many US hospitals are widely adopting new transfusion protocols that are commonly applied in the setting of obstetric hemorrhage.

Precautions for patients at risk of acute hemorrhage

Early transfer of care to a tertiary care facility

Timing of delivery

Advanced planning and interdisciplinary collaboration are fundamental for management of patients at risk of hemorrhage at delivery. Emergent non-planned deliveries after hours should be minimized.

Recent recommendations from the Society for Maternal-Fetal Medicine suggest that patients with placenta previa, previous myomectomies, and previous classic cesareans should be delivered at 36 to 37 weeks.4 Similarly, patients with suspected placental accretism should be delivered at 34 to 35 weeks.

Delaying delivery beyond 36 weeks has been associated with a significant risk of emergency delivery because of hemorrhage.5 In cases of placenta previa or accreta, cervical ultrasonography may help a clinician gauge the optimal time of delivery. Recent evidence suggests that patients with placenta previa and cervical lengths less than 30 mm have a higher risk of acute hemorrhage.6 If debate exists about whether to deliver at 34 weeks or no later than 37 weeks, clinicians can consider measuring cervical length with transvaginal ultrasound. For women whose cervices are shorter than 30 mm and with gestational ages greater than 34 weeks, we favor delivery to prevent emergent bleeding and emergent non-planned deliveries, rather than waiting a "few" more weeks.

Preoperative autologous blood banking

Preoperative autologous blood banking has not been evaluated in carefully designed studies, and is not common practice. Theoretically, a patient's hemoglobin will recover between donations (because of use of iron supplements).7 In practice, however, anemia is a limiting factor, and patients usually can donate only a few units throughout pregnancy (blood donation should be deferred if maternal serum hemoglobin is <10 g/dL).

Another limiting factor is that blood can only be collected within 42 days of any planned surgical procedure (maximum accepted time to maintain packed red blood cells [RBCs] in the blood bank).8 This technique will not prevent the risks associated with blood collection, storage, and administration, and is not acceptable for Jehovah's Witnesses.7

Overall, the technique is unlikely to reduce the amount of blood products transfused in emergency situations. Autologous donation should be used only in cases of rare blood types and/or patients with multiple antibodies (from previous alloimmunization) when availability of compatible blood products at the time of surgery may be limited.