Obstetric hemorrhage is a leading cause of maternal morbidity and mortality worldwide, particularly in developing nations. The majority of adverse outcomes in hemorrhage are likely preventable and are due to factors such as failure to recognize risk factors, inaccurate estimation of blood loss, and delays in resuscitation. One statewide review of maternal mortality found that 40% of cases were deemed potentially preventable with improved medical care, particularly in hemorrhage (93%).

1. Antepartum Hemorrhage occurs in approximately 25% of pregnancies but is infrequently life-threatening to the parturient; the fetus is at the highest risk. Most commonly, it arises from abnormal placentation.
1. Etiologies include the following:
1. Placenta previa is defined as a placenta that partially or completely covers the internal cervical os. Risk factors include prior previa, uterine scar from a previous surgery or procedure, increasing multiparity, and advanced maternal age. The classic presentation is painless vaginal bleeding during the second or third trimester. Ultrasound confirms the diagnosis. Of note, the presence of a placenta previa increases the risk of placenta accreta spectrum disorders, particularly in women with prior cesarean delivery.
2. Placental abruption is defined as complete or partial premature separation of the placenta from the uterus. Bleeding occurs because of the exposed vessels, and fetal distress may ensue from a loss of placental surface for oxygen and nutrient exchange. The etiology remains unclear, but risk factors are hypertension, advanced maternal age, increasing multiparity, trauma, prior history of abruption, tobacco and cocaine use, and preterm premature rupture of membranes. The classic presentation is vaginal bleeding, uterine tenderness, and painful, frequent contractions. The diagnosis is largely clinical because ultrasonography is specific (96%) but not sensitive (24%) for placental abruption. Of note, a significant amount of bleeding may be concealed in the retroplacental space. Placental abruption results in exposure of tissue factor and other factors that can result in consumptive coagulopathy and DIC. Other complications include hemorrhagic shock and fetal demise, with a perinatal mortality rate of 12%.
3. Uterine rupture is a rare complication of pregnancy with potential for significant maternal and fetal morbidity. The major risk factor is a previous uterine scar; in patients with a previous lower uterine segment incision, the incidence is less than 1%. The incidence is higher in patients with a history of a classical uterine incision; in these patients, rupture is associated with greater morbidity because of the vascularity of the anterior uterine wall and the possible disruption of the placental bed. Presentation is variable. The most common signs are abdominal pain (including breakthrough pain with neuraxial analgesia) and abnormal fetal heart tone (FHT).
2. Management: In all cases of antepartum bleeding, the first steps are maternal stabilization and assessment of fetal status. Providers should obtain large-bore IV access and blood for a type and screen and assess coagulation status and hemoglobin/hematocrit. Placental abruption and previa may be expectantly managed, depending on the degree of bleeding and gestational age. If preterm with minimal abruption and no evidence of compromise, delivery may be delayed for corticosteroid treatment. For a patient who is normovolemic and noncoagulopathic, labor and vaginal delivery may be considered. For significant bleeding, prompt delivery and aggressive volume resuscitation are critical. Previa and abruption place patients at increased risk for atony and development of coagulopathy, which should be anticipated and aggressively treated. Uterine rupture requires immediate delivery of the fetus, most commonly with general anesthesia to facilitate an exploratory laparotomy. The uterus may be repaired, but hysterectomy is sometimes required.
2. Postpartum Hemorrhage: The average blood loss for vaginal delivery and cesarean delivery is less than 500 and 1000 mL, respectively. Postpartum hemorrhage (PPH) may be defined as blood loss in excess of the level mentioned, or clinically as a 10% decrease in hematocrit from admission to the postpartum period. Primary PPH occurs within 24 hours, whereas secondary PPH occurs between 24 hours and 6 weeks postpartum.
1. Significant etiologies include the following:
1. Uterine atony is the most common cause of primary postpartum hemorrhage accounting for 80% of cases. Typically, uterine contraction (mediated by endogenous oxytocin) leads to constriction of spiral arteries, which contributes to hemostasis during delivery. Risk factors include prolonged labor, multiple gestations, high parity, chorioamnionitis, augmented labor, cesarean delivery, precipitous labor, tocolytic agents, and use of volatile anesthetics. Given the frequency of uterine atony, the ACOG recommends prophylactic treatment with uterotonics for all deliveries. Initial treatment should include bimanual massage, placement of large-bore IV access, volume resuscitation, and oxytocin infusion (0.3-0.6 IU/min). Further pharmacologic therapy may include administration of uterotonic medications such as methergine 0.2 mg intramuscular (IM), misoprostol 600 to 1000 µg buccal or per rectum (PR), and 15-methyl prostaglandin F2a 250 µg IM. Surgical intervention may be required, including a peripartum hysterectomy.
2. Placenta accreta occurs in three subtypes: placenta accreta, defined as adherence of the placenta to the myometrium without a decidual layer, placenta increta, defined as invasion into the myometrium, and placenta percreta, defined as invasion through the uterine serosa.
1. Risk factors for placenta accreta include a previous uterine incision or instrumentation, advanced maternal age, multiparity, assisted reproductive techniques, and a low-lying placenta or placenta previa. The incidence of accreta rises significantly when placenta previa is present in a patient with one or more previous uterine incisions, with an incidence of greater than 60% in women with placenta previa and three or more prior cesarean deliveries.
2. Diagnosis is usually made antenatally with ultrasonography and occasionally magnetic resonance imaging (MRI).
3. Management is typically planned preterm cesarean delivery with peripartum hysterectomy with the placenta left in situ. Internal iliac artery balloon catheters may be considered to decrease blood loss after delivery. Estimated blood loss exceeds 2 L in two-thirds of cases and may be precipitous; large-bore access and rapid volume resuscitation are essential.
3. Uterine inversion is a rare event that may cause significant hemorrhage because of ischemia of the fundus, precipitating uterine atony. The first-line treatment is manual replacement of the uterus, which is facilitated by discontinuation of uterotonic agents and administration of uterine relaxants (eg, nitroglycerin IV or sublingual, terbutaline, magnesium). This is followed by aggressive medical management (readministration of uterotonic medications) to improve uterine tone and limit further hemorrhage.
4. Retained placenta is defined as failure of placental separation within 30 minutes of delivery. Management involves the removal of the placenta manually or with curettage and may require uterine relaxation through additional neuraxial analgesia or IV nitroglycerin.
2. Invasive treatment options to control PPH include intrauterine balloon placement, uterine compression (B-Lynch) sutures, uterine artery embolization or ligation, and perioperative hysterectomy.
3. Chapter 34 discusses optimal resuscitation and transfusion in hemorrhagic shock in nonpregnant patients. Tranexamic acid (TXA) reduces the risk of death due to bleeding in the setting of PPH without increasing the risk of thrombotic events (1 g IV plus an additional 1 g IV if bleeding continues after 30 minutes). Traditional, trauma-based resuscitation with 1:1:1 product transfusion is often used in the peripartum period despite the hematologic changes of pregnancy that may not warrant such aggressive factor replacement. The use of rotational thromboelastometry (ROTEM) and thromboelastography (TEG) has expanded over the past decade and there are pregnancy-specific resuscitation algorithms that have been developed targeting higher fibrinogen levels in this population. Studies have shown that viscoelastic-guided resuscitation reduces the number of blood products transfused and may reduce the need for hysterectomy and ICU admission in the peripartum population.