Postpartum Hemorrhage
Divya Dethier
Julianna Schantz-Dunn
OVERVIEW
Postpartum hemorrhage (PPH) is a leading cause of maternal mortality affecting 1% to 5% of all deliveries, although the incidence varies widely. PPH is the leading cause of maternal mortality in low-income countries, causing one-quarter of all maternal deaths globally.1 In the United States, PPH accounts for greater than 10% of maternal mortality and is the primary contributor to maternal morbidity.2 The most common cause of PPH is uterine atony.3 PPH is a clinical diagnosis, and timely recognition and active management of the third stage of labor are key to the effective treatment of PPH and reduction of maternal morbidity and mortality.
Definition
PPH is diagnosed clinically by health care providers using assessment of blood loss, known as “estimated blood loss” (EBL). There are various objective definitions for PPH, which range from blood loss of >500 cc (minor PPH) to >1000 cc (severe PPH) or blood loss that is accompanied by signs or symptoms of hypovolemia. In 2017 the American College of Obstetricians and Gynecologists (ACOG) changed the definition of PPH to a blood loss of greater than 1,000 cc accompanied by signs or symptoms of hypovolemia regardless of the route of delivery.4
DIAGNOSIS
There are several tools to aid in the diagnosis of PPH including assessments of blood loss, hemodynamic changes, and laboratory studies.
Blood Loss Assessment Methods
In the emergency department (ED), disposable absorbent underpads (chux) are placed under patients at the time of delivery; a rough estimate for blood loss is weighing the absorbent underpad (with 1 g = ˜1 cc of blood). Therefore, a simple way to help quantify blood loss during or after a delivery is by weighing all disposable underpads on a scale near the patient. If possible, take into account that there may be fluids other than blood that have been absorbed, such as amniotic fluid, irrigation fluid, or urine.
An underbuttocks drape (ideally a graduated drape) that collects blood as it is lost vaginally is another tool to quantify blood loss. If the drape is not graduated, or there is no access to a plastic drape, a garbage bag can be used under the patient directed into a bucket to collect the blood. The blood can then be transferred into a urine collection hat or other container with volumetric gradations. Understanding how much blood laparotomy pads or vaginal pads hold can help estimate any additional blood loss, although these are not often used in the emergency setting (Figure 27.1).5
 Figure 27.1: Visual guide for determining blood loss for three different sizes of gauze. (From Ali Algadiem E, Aleisa AA, Alsubaie HI, Buhlaiqah NR, Algadeeb JB, Alsneini HA. Blood loss estimation using gauze visual analogue. Trauma Mon. 2016;21(2):e34131.) |
Hemodynamic Changes
PPH is characterized by excessive bleeding, which may lead to signs of hypovolemia including tachycardia and hypotension. The signs and symptoms of hemodynamic instability guide the diagnosis and treatment of PPH. Blood loss of 10% to 15% (500-1000 cc) may result in a patient with mild tachycardia, but a blood pressure that is within normal limits. For blood loss of 15% to 25% (1000-1500 cc), patients will generally exhibit tachycardia (100-120 bpm), feel unwell, and likely be hypotensive. In many healthy, young women, however, it is not until a blood loss of 25% to 35% (1500-2000 cc) that vital signs may alert a health care provider to a problem, with tachycardia in the 120 to 140 beats per minute (bpm) range and systolic blood pressure below 90 mm Hg.6
The maternal physiologic changes occurring throughout pregnancy are adaptive and protective of blood loss at the time of delivery. The average circulating blood volume for a term pregnant woman is 6 liters. Due to the large expansion in plasma volume during pregnancy (that exceeds the expansion of red cell volume), pregnant women have a “physiologic anemia.” Pregnant patients have increased cardiac output as well as decreased systemic vascular resistance and blood pressure. By the third trimester, the uterus is receiving 15% of maternal cardiac output, which is equivalent to 500 cc/min. As a result, with active bleeding in PPH, there can be significant blood loss in a short amount of time.
The key to recognizing PPH is that it can evolve quickly. Furthermore, patients vary on the amount of blood loss they can tolerate before showing signs of hypovolemia. A woman with hypertensive disorder of pregnancy who exhibits a systolic blood pressure of 100 to 110 mm Hg may have already lost 30% of her blood volume while maintaining a “normal” blood pressure. Patients who are otherwise young and healthy can compensate well and may show signs of hemodynamic instability only after a significant amount of blood loss. Many women have anemia at the time of delivery, and patients with a low starting hemoglobin may show signs of hemodynamic instability with less quantitative blood loss.
ETIOLOGY
The major causes of PPH are represented by the mnemonic “Four T’s”: uterine atony (Tone), lacerations (Trauma), retained products or placental disorders (Tissue), and coagulation defects (Thrombin) (Table 27.1).3,7
TABLE 27.1 The “Four T’s” Mnemonic Device for Causes of Postpartum Hemorrhage | ||||||||||||||||||
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Tone
Uterine atony is the most common cause of PPH. Atony means the uterus is not effectively contracting after delivery and feels soft or “boggy.” The diagnosis is made by palpating the uterus and feeling a lack of firmness despite uterine massage and oxytocin (given in the third stage of labor when the placenta is being delivered). Risk factors for uterine atony include conditions that prevent the uterus from contracting down or lead to overdistention of the uterus (Table 27.2).
After delivery, palpate the uterine fundus to assess for firmness. If the fundus is firm, it does not necessarily mean that the entire uterus is firm. Often, the lower uterine segment can be boggy or poorly contracted, while the fundus feels firm. This may be caused by a blood clot that is preventing the lower part of the uterus from contracting down. A bimanual examination is helpful to assess lower uterine segment tone and the presence of retained clots.
Trauma
PPH may result from trauma to the uterus or the genital tract, either from lacerations or surgical incisions. Between 60% and 90% of women who deliver vaginally will have a perineal laceration.8,9 Cervical and vaginal lacerations can lead to excessive vaginal bleeding; therefore, a detailed visual inspection of the lower genital tract should be conducted if a source is not readily identified. Externally visible tears include perineal lacerations or labial lacerations.
Vaginal lacerations or sulcal lacerations (tears that run deeply into the posterior vagina) as well as cervical lacerations can often bleed heavily due to the large blood supply to the vagina and cervix in term gestations and require good visualization to identify with retraction of the vaginal walls.
Tissue
Retained products (placenta or membranes) or abnormally adherent placenta (placenta accreta) may cause hemorrhage. Inspecting the placenta after delivery to ensure the maternal side is intact is a good initial step toward recognizing retained placenta. A bedside ultrasound can be used with Doppler color flow to identify retained products or blood clots inside the endometrium. If there
is concern for retained products, perform a manual sweep inside the uterus to clear out any clots or products that may still be inside. If the placenta is not separating easily, call for help because an abnormally adherent placenta may require an urgent hysterectomy.
is concern for retained products, perform a manual sweep inside the uterus to clear out any clots or products that may still be inside. If the placenta is not separating easily, call for help because an abnormally adherent placenta may require an urgent hysterectomy.
TABLE 27.2 “Risk Factors for Uterine Atony” | ||||
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Thrombin
Inherited or acquired coagulation defects are another potential etiology of PPH. Inherited bleeding disorders include thrombocytopenia and clotting factor deficiencies (such as von Willebrand’s, hemophilias). Therapeutic anticoagulation may also be a cause of hemorrhage. Acquired coagulation defects include preeclampsia; hemolysis, elevated liver function tests, and low platelet (HELLP) syndrome; acute fatty liver of pregnancy; sepsis; amniotic fluid embolism; placental abruption; and intrauterine fetal demise. These conditions may cause an imbalance in the hemostatic and fibrinolytic systems that lead to disseminated intravascular coagulation (DIC), which is a widespread activation of the clotting cascade with depletion of coagulation factors and platelets resulting in uncontrolled hemorrhage.10,11 In consumptive coagulopathies of pregnancy, fibrinogen is consumed more rapidly than other factors and is critical to anticipate as failure to replete coagulation factors prior to administration of other blood products or fluids can worsen the underlying coagulopathy.
CLINICAL FEATURES
The clinical evaluation of PPH is based on the physical examination and careful assessment of signs and symptoms suggestive of hypovolemia. Tachycardia will be the first sign of compensated shock, followed by decreasing blood pressure and must be considered in the context of the patient’s baseline vital signs.
Physical Examination
Bimanual Examination
A bimanual examination is the first step in any patient presenting with postpartum bleeding (Figure 27.2). This examination may be uncomfortable for the patient, especially without any form of anesthesia. The provider should place the nondominant hand on the woman’s abdomen and begin an external massage of the uterus with downward pressure. Place the gloved dominant hand
into the vagina and through the cervical opening to clear any vaginal clots or clots from the uterus, particularly if they are in the lower uterine segment and preventing uterine contraction. Assess the uterine tone, including the lower uterine segment, by using the nondominant hand to massage the uterus externally and feel the uterine tone between both hands. Clearing clots out of the lower uterine segment and massaging the uterus help the uterus contract down and stop bleeding. A full bladder can prevent the lower uterine segment from contracting and can shift the uterus off to one side or another. Placement of a Foley catheter assists in ongoing monitoring of maternal hemodynamic status and may promote adequate uterine contraction.7,12
into the vagina and through the cervical opening to clear any vaginal clots or clots from the uterus, particularly if they are in the lower uterine segment and preventing uterine contraction. Assess the uterine tone, including the lower uterine segment, by using the nondominant hand to massage the uterus externally and feel the uterine tone between both hands. Clearing clots out of the lower uterine segment and massaging the uterus help the uterus contract down and stop bleeding. A full bladder can prevent the lower uterine segment from contracting and can shift the uterus off to one side or another. Placement of a Foley catheter assists in ongoing monitoring of maternal hemodynamic status and may promote adequate uterine contraction.7,12
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