KEY QUESTIONS
What are the most common obstetric (OB) traumas, their the management considerations, and the impact on pregnancy?
What should the initial evaluation of an OB trauma include?
What is the most appropriate type of imaging to obtain, and how should patients be counseled about the risks involved?
CASE 50-1
A 26-y.o. G2P1001 at 35 and 3/7 weeks gestation presents to the ED after a high-impact motor vehicle collision (MVC). As per EMS, the patient was a restrained driver of a car traveling 50 mph on the highway when a car rear-ended her as she came to an abrupt stop. The airbag deployed, and the patient’s abdomen was hit by it. She did not hit her head or lose consciousness. She is brought in by ambulance to the trauma room stable; however, she is mildly tachycardic and reports severe abdominal pain.
Upon arrival, the OB and Trauma teams are present. She is cleared by the primary survey. A FAST scan shows minimal blood in the right upper quadrant. History is taken and is unremarkable. Physical exam shows moderate amount of bright red blood at the perineum and patient’s abdomen is severely tender. FHR tracing (FHRT) is Category I however, on tocometry the patient is contracting every minute.
Trauma in pregnancy is a relatively common occurrence, affecting 1 in 12 pregnancies. It is broadly divided into blunt and penetrating injury, which can vary widely in both severity and mechanism. The most common mechanism of blunt injury is motor vehicle collisions (MVCs), followed by falls and assaults. Penetrating injuries, such as gunshot and stab wounds, are much less common than blunt injuries. Approximately 1% to 4% of pregnant women will be hospitalized due to traumatic injury; it is the leading cause of nonobstetrical maternal death. Homicide and suicide attempts are infrequent in pregnancy. Overall, the most common mechanisms of injury for maternal and fetal mortalities are MVCs (73%), followed by falls (14%) and automobile-pedestrian collisions (13%). Fortunately, the overall maternal mortality rates after trauma are relatively low (< 3.8%). However, factors such as the need for a cesarean delivery soon after trauma, penetrating trauma, and lack of restraint use during an MVC all increase the mortality risk to both mother and fetus. In addition, head injuries, a low Glasgow Coma Scale (GCS), a high Injury Severity Score (ISS), internal injuries, and shock on admission are associated with worse maternal outcomes and increased fetal loss.
Approximately 1 in 4 women will fall at least once during pregnancy, and the incidence of injury from such falls is 48.9 per 100,000 live births from falls. Physiologic changes that occur with pregnancy, such as increased joint laxity, weight gain, and postural changes, increase the risk of falls. Dynamic postural stability decreases with pregnancy, especially during the third trimester; 79% of pregnant women hospitalized after a fall were in their third trimester. Among such women, lower-extremity fractures were the most commonly associated injury, followed by contusions and sprains. The majority of falls occur indoors, and 39% involve falling down stairs. Exercise during pregnancy contributes an overall injury incidence of 4.1 cases per 1000 exercise hours, the majority of which involve falls. Falls also may occur at the workplace, with one study reporting that 6.3% of all employed pregnant workers fell at work. The major risk factors for falling at the workplace included walking on slippery floors, hurrying, or carrying heavy objects. In an analysis of 693 hospitalized pregnant patients admitted after a fall, this study reported a 4.4-fold increase in preterm labor, an 8-fold increase in placental abruption, a 2.1-fold increase in fetal distress, a 2.9-fold increase in fetal hypoxia, and a 2.1-fold increase in fetal death when compared to a randomly selected control group. Even in women who were hospitalized and discharged without delivering, this group of women continued to have an increased risk of adverse pregnancy outcomes, including a 5.3-fold increase of preterm labor, an 8.5-fold increase in placental abruption, a 2-fold increase in fetal distress, and 4-fold increase in fetal hypoxia when compared to women without a history of falls.
The incidence of MVCs during pregnancy has been estimated at approximately 207 cases per 100,000 live births. It is one of the leading causes of both maternal and fetal mortality, at 1.4 per 100,000 and 3.7 per 100,000 pregnancies, respectively. In an analysis of 25,168 pregnant women who were in one or more MVCs during pregnancy, there was a 1.54-fold increase in preterm births, 4.82-fold increase in stillbirths, and 2.97-fold increase in placental abruptions. The risk of stillbirth was even more elevated in pregnancies with multiple crashes (4.82) or involving unbelted pregnant drivers (6.28). The use of illicit drugs and alcohol is a major risk factor for MVCs during pregnancy; data from the National Trauma Data Bank created by the American College of Surgeons associates 19.6% of pregnancy-related traumas with the use of illicit drugs, and 12.9% with the use of alcohol. The statistics of estimated incidence of injury by type of trauma are given in Figure 50-1.
FIGURE 50-1.
Estimated incidence of injury by type of trauma during pregnancy. Rates are reported per 100,000 live births in pregnancy and per 100,000 women in the nonpregnant cohort. Rates for nonpregnant women were calculated using 2013 US data from the CDC web-based Injury Statistics Query and Reporting System (WISQARS) (2015) when not available from the literature. (Reproduced with permission from Yeomans ER, Hoffman BL, Gilstrap LC III, et al: Cunningham and Gilstrap’s Operative Obstetrics, 3rd ed. New York, NY: McGraw-Hill Education; 2017.)
The reported incidence of domestic violence (DV) and intimate partner violence (IPV) varies widely, from 10% to 30% of pregnant women, and injury from DV/IPV is estimated to be 8307 per 100,000 live births. All pregnant women should be screened for DV/IPV during their prenatal visits. Healthcare providers should have increased suspicion of DV/IPV in patients with the following risk factors: unintended pregnancy, depression, substance abuse, low socioeconomic status, history of DV prior to pregnancy, and recurrent injuries. The pattern of injury in cases of DV/IPV typically are more proximal extremities or closer to the midline, as opposed to falls and MVCs, which more commonly involve the distal extremities, pelvis, and abdomen.
Pregnant women exposed to DV/IPV typically present with injuries to the neck, breast, face, upper arms, and lateral thighs as well as with injuries such as cigarette burns and bite marks. DV/IPV is associated with an increased risk of adverse pregnancy outcomes such as spontaneous abortion, neonatal intensive care unit (NICU) admission, preterm birth, low birth weight, and postpartum depression.
The Centers for Disease Control and Prevention (CDC) has consistently ranked suicide in the top three leading causes of death for women aged 15 to 34 years old for the past five years. Although pregnancy seems to be a protective factor, with an estimated prevalence of 2 per 100,000 live births compared to 8.8 per 100,000 in the general population, it is still a significant contributor to fetal death in pregnancy. Suicide is often associated with DV/IPV and may be a factor in up to 54% of suicide cases among pregnant women. Other risk factors include depression, severe mental illness, substance abuse, low socioeconomic status, and unmarried teen pregnancy. Another major risk factor in mothers attempting suicide, particularly during the postpartum period, is fetal or infant death, which one study found resulted in a 3.1-fold increase in suicide attempts. In a review of 2132 cases of unsuccessful suicide attempts, there was an increased risk of adverse maternal complications such as preterm labor, cesarean delivery, and need for blood transfusion. Increased neonatal complications included respiratory distress and low birth weight, which persisted after adjusting for gestational age. The most common method of attempted suicide and suicide during pregnancy was poisoning/overdosing (80%–90% of cases); other methods such as cutting, jumping from high places, and MVCs were significantly less common.
Although rare, the incidence of homicide is estimated at 2.9 per 100,000 live births, and it is among the top three leading causes of death for all women of childbearing age, independent of pregnancy status. Risk factors for homicide during pregnancy include being teenage, being African-American, and getting late or no prenatal care. The most common mechanisms for injury by homicide are gunshot (58%), stabbing (18%), strangulation (14%), and battery (8%). Because a large proportion of homicides are due to penetrating trauma, this classification of injury is significantly associated with increased fetal mortality (possibly up to 73%), increased maternal mortality (up to 7%), and increased hospital stays compared to blunt trauma.
OB providers will encounter a wide spectrum of traumas in their practice, which depends on the hospital location, size, degree of specialization, and trauma level designation. Although the criteria vary by region, trauma centers are generally classed into one of five levels, with Level 1 centers offering the most comprehensive services and Level 5 centers offering the fewest services. In general, pregnant trauma victims with a known or suspected gestational age > 20 weeks should be transported to a Level 1 trauma center. A 2016 study that looked at 429 injured pregnant women showed improved neonatal outcomes with respect to preterm delivery and birth weight when patients were provided care at a trauma-designated hospital. A hospital’s trauma center level can be found on: http://www.amtrauma.org/?page=findtraumacenter.
The initial evaluation and management of gravid injured patients follows the same systematic approach as for nongravid patients, as laid out in the Advanced Trauma Life Support course offered by the American College of Surgeons. This approach begins with the primary survey and continues with the secondary survey, as well as the adjuncts, which may include necessary life-saving maneuvers and advanced imaging. The initial approach to treating the pregnant patient includes the same issues and concerns as any other patient, with added considerations for the variant anatomy and physiology as well as the care of a second patient—namely, the fetus. While it is beyond the scope of this chapter to address the entire spectrum of trauma care comprehensively, the significant aspects of the trauma resuscitation are described here. The obstetrician is a critical member of the trauma response team for pregnant trauma patients, particularly when the fetus has reached periviability. Optimally, this is estimated in the prehospital setting, and the obstetrical team is notified while the patient is en route.
Additional physiologic considerations that must be recognized in caring for a pregnant trauma patient include the relative hypervolemia of pregnancy, the sensitivity of the fetus to any degree of maternal hypoxia, and the capacity for the gravid uterus to compress the inferior vena cava in a supine patient. Relative hypervolemia can delay the physiologic changes normally seen with shock states; therefore early fluid resuscitation should be considered for all pregnant trauma patients. The discrepancy in the oxyhemoglobin dissociation curves between fetal blood and maternal blood means that small increases in maternal oxygen content improve fetal oxygen content dramatically; therefore even mild hypoxia should be avoided. Positioning of a pregnant trauma patient in the third trimester may require manual uterine displacement or a wedge placed under the right side of the pelvis to alleviate compression of the vena cava and provide adequate venous return to the maternal heart. Finally, the treatment priority in all pregnant trauma patients is maternal survival, and this should be the primary goal of the resuscitation.
The essential purpose of the primary survey is to identify and address immediate life-threatening injuries. It follows the mnemonic the ABCs, with A standing for airway, B for breathing, and C for circulation; in addition, there is D for disability (neurologic assessment and the GCS), and E for exposure of the patient/environment of the trauma. The ABCs are listed in Figure 50-2.
It is critical to ensure an adequate protected airway for significantly injured pregnant patients. With a relaxed gastroesophageal sphincter and increased intra-abdominal pressure, gravid patients are more susceptible to aspiration. This is a concern, as traditionally trauma patients are kept lying flat on a gurney for much of the time. Rapid sequence intubation is the strategy of choice, although lower doses of succinylcholine should be used to accommodate decreases in pseudocholinesterase in pregnancy. Supplemental oxygen should be used liberally because adequate oxygenation is more critical to the pregnant trauma patient than usual. Levels of hypoxia that are common during trauma resuscitation, but relatively benign to the nonpregnant patient, can have a significant impact on the fetus.
Due to the relative hypervolemia of pregnancy, early shock can be difficult to recognize and may lead to delays in fluid resuscitation or management of hemorrhage. It is critical to pursue potential sources of hemorrhage and intervene as appropriate. More recently, patients with significant injuries causing hemodynamic instability have been managed with an approach called damage controlled resuscitation. Central to this approach is an emphasis on early and balanced blood product resuscitation, such as a 1:1:1 Packed Red blood cells (PRBC) / Fresh Frozen Plasma (FFP) /platelet infusion. The fundamental benefit of this, beyond volume replacement and improved oxygen-carrying capacity, is an attenuation of the coagulopathy of trauma.
The essential purpose of the secondary survey is to identify and address potentially life-threatening injuries. It follows the primary survey (as its name implies) and includes a trauma-specific history that includes issues related to the pregnancy as well as a comprehensive physical exam. The history follows the mnemonic AMPLE: A for allergies, M for medications, P for past medical/surgical history, L for last meal, and E for events of the trauma. At the same time, it is critical to determine the estimated date of delivery as well as pertinent obstetrical history. At this point, the OB team should be present at the bedside to determine the estimated due date and obtain a detailed obstetrical history, including current complications of the pregnancy and any complications of prior pregnancies. The physical exam and bedside ultrasound can be used to determine or confirm the gestational age.
Adjuncts to the primary survey include arterial blood gas (ABG), pulse oximetry, electrocardiogram (ECG) tracing, Foley catheters, and gastric catheters. In patients with neurologic or chest trauma, it is important to remember that hypocapnia is normal in pregnancy. Thus a normal CO2 level may be an early indicator of pulmonary failure. Chest x-ray and sometimes pelvic x-rays are other adjuncts to the primary survey, as they are useful to quickly identify sources of hemorrhage or shock, such as pneumothorax or pelvic fractures. While the uterus should be shielded whenever possible, x-ray evaluation should be performed in the same way as for any trauma patient due to the relatively low radiation exposure.
The Focused Assessment with Sonography in Trauma (FAST) scan is a critical adjunct to the secondary survey that should be performed in all trauma patients, particularly at teaching institutions. The extended version of this bedside procedure includes six views: the right upper quadrant, or Morison’s pouch; the left upper quadrant, encompassing the spleen and left kidney; the suprapubic view, to identify free fluid around the bladder; the subxiphoid, to assess for pericardial tamponade; and finally, left and right anterior chest views, to identify the presence of lung sliding, which rules out a pneumothorax. There is some debate as to the sensitivity and specificity of this exam in the pregnant patient, particularly in the last trimester. However, given the speed with which this procedure can be performed, the fact that it can readily be repeated, and the near-zero risk of bedside ultrasonography, its use is strongly supported. It is important for the operator to understand that while some pelvic fluid is physiologic in pregnancy, the volume of that fluid rarely exceeds 20 mL, meaning that any fluid ascertained on the FAST exam should be considered pathologic. Figure 50-3 shows a sample of a FAST scan.
FIGURE 50-3.
Fast scan. Upper quadrant scan shows anechoic free fluid (asterisk) between the liver edge (arrow) and kidney (Morison pouch). The patient had 2500 mL of blood in the peritoneal cavity. (Reproduced with permission from Yeomans ER, Hoffman BL, Gilstrap LC III, et al: Cunningham and Gilstrap’s Operative Obstetrics, 3rd ed. New York, NY: McGraw-Hill Education; 2017.)
The initial labs obtained during a trauma are critical to making the proper evaluation. When approaching care of a pregnant woman, the physiologic changes of pregnancy should be taken into account as lab values are interpreted. The common labs ordered during a trauma evaluation are comprehensive metabolic panel (CMP); Kleihauer-Betke (KB) test; complete blood count (CBC); blood type and screen; amylase; lipase; urine drug screen; coagulation profile, including international normalized ratio (INR); prothrombin time (PT); fibrinogen; and partial thromboplastin time (PTT). Figure 50-4 lists the common lab tests, along with other evaluation tests for the pregnant trauma patient.
In normal pregnancy, the white blood cell (WBC) count may be as high as 17 × 109/L, meaning that leukocytosis alone is not a predictor of abnormality. Although an elevated WBC level may be within normal limits in pregnancy, the acceptable range of WBC depends on the trimester. In the nonpregnant female, a WBC value of 9.1 × 109/L is the upper limit of normal, whereas in the first, second, and third trimester, the upper limits are 13.6, 14.8, and 16.9 (× 109/L), respectively. Leukocytosis should be correlated with clinical findings, other labs, and imaging studies to confirm injury, infection, or inflammation.
Fibrinogen in pregnancy is often > 4 g/L, and a value in the normal range (2.5–3 g/L) could signify hyperfibrinogenemia in the pregnant patient. D-dimer is also usually elevated in pregnancy and may be difficult to interpret as a marker for deep venous thrombosis (DVT). In the nonpregnant individual, D-dimer should be < 2.7; however, the upper limit of normal in the first, second, and third trimesters are 5.2, 7.1, and 9.3 (nmol/L), respectively.
In ABG analysis, normal baseline levels of carbon dioxide are decreased to 27 to 32 mmHg due to an increase in respiratory minute volume, and a value of 40 mmHg may represent hypoventilation. Due to a 50% increase in the glomerular filtration rate (GFR) and concomitant hemodilution, the normal serum creatinine in pregnancy is decreased to 50 to 60 µmol/L, meaning that a value of 90 µmol/L may be abnormal. This discussion is limited, however, and only meant to prompt the reader to be mindful of the interpretation of values for a pregnant patient. Normal reference ranges and laboratory values in pregnancy can be found on the Perinatology.com website: http://perinatology.com/Reference/Reference%20Ranges/Reference%20for%20Serum.htm
Isoimmunization occurring from the D antigen of the Rh blood group is preventable in almost all cases, and any pregnant woman presenting after a trauma should have a blood type and screen obtained. The routine administration of RhoGAM in the third trimester has reduced the incidence of isoimmunization from 16% of women to 1% during pregnancy, and to 0.1% to 0.3% with administration of a second dose in the postpartum period. However, a small percentage of the at-risk population becomes isoimmunized because of the inadvertent missed administration of RhoGAM or due to unrecognized fetomaternal bleeding that occurred before the third-trimester dose was given. In pregnant patients that are Rh negative and involved in a traumatic event, RhoGAM should be given, regardless of gestational age, to prevent isoimmunization in subsequent pregnancies. RhoGAM also should be given if the provider is uncertain whether it had been administered previously, if more than 12 weeks has passed since the dose at the time the patient presents, or both.
A standard 300-mcg dose is enough to suppress the immune response to 30 mL of fetal D+ red blood cells (RBCs), while a 50-mcg dose is enough for 5 mL. The amount of fetomaternal hemorrhaging needs to be calculated after a trauma to ensure that the appropriate dose of RhoGAM is given. The KB test estimates the amount of fetomaternal hemorrhaging, which aids in calculating the dose of RhoGAM to be given. It should be obtained for all patients that are Rh negative so that the dose of RhoGAM can be decided upon.
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