Postpartum Hemorrhage in Emergency Medicine 

Defining postpartum hemorrhage (PPH) is problematic and has been historically difficult. Waiting for a patient to meet the postpartum hemorrhage criteria, particularly in resource-poor settings or with sudden hemorrhage, may delay appropriate intervention. Postpartum hemorrhage is traditionally defined as blood loss greater than 500 mL during a vaginal delivery or greater than 1,000 mL with a cesarean delivery. However, significant blood loss can be well tolerated by most young healthy females, and an uncomplicated delivery often results in blood loss of more than 500 mL without any compromise of the mother's condition.

The addition of "a 10% drop in hemoglobin" to the definition provides an objective laboratory measure. However, this is not helpful in acute situations since it can take hours for losses to create laboratory changes in red blood cell measurements. Signs and symptoms of hypovolemia (lightheadedness, tachycardia, syncope, fatigue and oliguria) are also of limited utility as they can be late findings in a young and otherwise healthy female. As a result, any bleeding that has the potential to result in hemodynamic instability, if left untreated, should be considered postpartum hemorrhage and managed accordingly.

Postpartum hemorrhage can be divided into 2 types: early postpartum hemorrhage, which occurs within 24 hours of delivery, and late postpartum hemorrhage, which occurs 24 hours to 6 weeks after delivery. Most cases of postpartum hemorrhage, greater than 99%, are early postpartum hemorrhage. Notably, most women are still under the care of their delivering provider during this time. With many women delivering outside of hospitals and early postpartum hospital discharge being a growing trend, postpartum hemorrhage that presents to the emergency department may be either early or late.

Within this combined population, emergency medicine providers are likely to receive patients that fall into 1 of 3 categories:

• Those that are too close to delivery to be transferred to another location (the facility's labor and delivery suite or to another facility)
• Women who delivered at home, at a nonhospital facility, or en route to the hospital and are too hemodynamically unstable to be transferred to a labor and delivery floor within the facility or at another location
• Patients who were discharged home after delivery in stable condition, but had concerning bleeding that prompted an emergency department visit

At term, the uterus and placenta receive 500-800 mL of blood per minute through their low resistance network of vessels. This high flow predisposes a gravid uterus to significant bleeding if not well physiologically or medically controlled. By the third trimester, maternal blood volume increases by 50%, which increases the body's tolerance of blood loss during delivery.

Following delivery of the fetus, the gravid uterus is able to contract down significantly given the reduction in volume. This allows the placenta to separate from the uterine interface, exposing maternal blood vessels that interface with the placental surface. After separation and delivery of the placenta, the uterus initiates a process of contraction and retraction, shortening its fiber and kinking the supplying blood vessels, like physiologic sutures or "living ligatures."

If the uterus fails to contract, or the placenta fails to separate or deliver, then significant hemorrhage may ensue. Uterine atony, or diminished myometrial contractility, accounts for 80% of postpartum hemorrhage. The other major causes include abnormal placental attachment or retained placental tissue, laceration of tissues or blood vessels in the pelvis and genital tract, and maternal coagulopathies. An additional, though uncommon, cause is inversion of the uterus during placental delivery.

The traditional pneumonic "4Ts: tone, tissue, trauma, and thrombosis" can be used to remember the potential causes. Here, a 5^th is added; “T” for uterine inversion that will be called “traction.”

Frequency

United States

The incidence of postpartum hemorrhage is about 1 in 5 pregnancies, but this figure varies widely due to differential definitions for postpartum hemorrhage.

Mortality/Morbidity

Mortality

Although accountable for only 8% of maternal deaths in developed countries, postpartum hemorrhage is the second leading single cause of maternal mortality, ranking behind preeclampsia/eclampsia.^[1] Globally, postpartum hemorrhage is the leading cause of maternal mortality. The condition is responsible for 25% of delivery-associated deaths,^[2] and this figure is as high as 60% in some countries. International initiatives to improve outcomes have invested in training birth attendants (traditional or otherwise) and nurse midwives on the active management of the third stage of labor (the period immediately after delivering of the infant). Most efforts focus on uterine atony, which is the primary cause of postpartum hemorrhage. This has included education on manual techniques to increase uterine contraction-retraction and making pharmacologic uterotonic agents (oxytocin and misoprostol) more available.^{[3, 4, 5]}

Morbidity

Postpartum hemorrhage is a potentially life-threatening complication of both vaginal and cesarean delivery. Associated morbidity is related to the direct consequences of blood loss as well as the potential complications of hemostatic and resuscitative interventions.

Consequences of uncontrolled hemorrhage

• Hypovolemic shock and associated organ failure including renal failure, stroke, myocardial infarction
• Postpartum hypopituitarism (Sheehan syndrome): Acute blood loss and/or hypovolemic shock during and after childbirth can lead to hypoperfusion of the pituitary and subsequent necrosis. Although often asymptomatic, it may present with an inability to breastfeed, fatigue, hypogonadism, amenorrhea, and hypotension.
• Death secondary to hypovolemic shock

Consequences of fluid resuscitation

• Fluid overload can lead to extremity edema and pulmonary edema. The latter is less common in young healthy women, but it should be suspected in the setting of large fluid and blood product resuscitation.
• Dilutional coagulopathy occurs when crystalloids and/or serum-poor blood products are given in large volume.

Risks from exposure to blood products

• Allergic or febrile reactions have an incidence of about 1 case per 333 population.^[6]
• Anaphylactic reactions occur in 1 in 20,000 to 1 in 47,000 blood products transfused.^[7]
• Transfusion-related acute lung injury (TRALI) occurs in 1 out of every 5,000 transfusions, but more often with high plasma containing products like fresh frozen plasma (FFP) and platelets. It often starts within 1-2 hours of the transfusion, but it can happen anytime up to 6 hours after a transfusion. The symptom complex includes severe bilateral pulmonary edema, severe hypoxemia, tachycardia, cyanosis, hypotension, and fever.^[8]
• Acute immune hemolytic reaction, though rare, is the most serious type of transfusion reaction. Symptoms are associated with red blood cell hemolysis. Patients may have fevers, chills, chest and lower back pain, nausea, renal failure, and death if the transfusion is not stopped.
• Delayed hemolytic reaction: This type of reaction happens when the body slowly attacks antigens (other than ABO antigens) on the transfused blood cells. Symptoms occur days to weeks after a transfusion. Affected patients are either asymptomatic or have mild symptoms, which may include jaundice, low-grade fever, and a low hemoglobin or hematocrit.^[9]
• Infection: Hepatitis is the most common disease transmitted by blood transfusions. According to the American Red Cross, about 1 blood transfusion in 205,000 transmits a hepatitis B infection, and 1 blood transfusion in about 2 million transmits hepatitis C. Other rare but potential infections include HIV (risk of 1 in 2.5 million), Lyme disease, babesiosis, and malaria. Donors are screened for potential exposure so transmission is very rare. Rarely, blood may be contaminated with tiny amounts of skin bacteria during donation. Platelets are the most likely blood product to be affected by contamination from skin flora.
• Metabolic reactions: With large volume and rapid transfusions, patients are at risk of encountering 3 metabolic reactions: hypothermia, hyperkalemia, and citrate toxicity. Hypothermia results from the transfusion of unwarmed crystalloid or colloid that drops the body temperature. Hypothermia inhibits coagulation and can worsen postpartum hemorrhage. Citrate is a blood product additive that binds serum calcium and can cause hypocalcemia with large-volume transfusions. Hemolysis occurs with red blood cell storage releasing increasing amounts of intracellular potassium with time. Transfusions of older red blood cells increase the risk of hyperkalemia.

Risks associated with surgical intervention

• Intubation and anesthesia complications: Pregnant women have an increased risk for aspiration, failed intubation, and death from failed ventilation when compared with nonpregnant patients. Respiratory injury or infection, myocardial infarction, myocardial arrhythmia, stroke, or allergic reactions to anesthetic medications may also rarely occur.
• Bleeding: Continued bleeding from the genital tract or a bleeding complication from the surgery may occur.
• Infection: Sepsis, wound infection, or pneumonia is possible.
• Deep venous thrombosis and/or pulmonary embolism: Risk is increased due to postpartum and postoperative associated hypercoagulability as well as from relative immobility in the operative and postoperative period.

Need for permanent sterilization to control bleeding

If the bleeding cannot be controlled conservatively (removal of products of conception, suturing disrupted tissues, application of pressure) then surgical intervention may be necessary. In severe cases, the following may occur:

• Hysterectomy
• Asherman syndrome, which is secondary (non-hormone mediated) amenorrhea due to uterine scarring that develops after infection and/or curettage performed to remove placental fragments