Trauma in Pregnancy
Trauma is estimated to complicate 1 in 12 pregnancies and is the leading cause of nonobstetric maternal death in the United States (Mendez-Figueroa, Dahlke, Vrees, & Rouse, 2013). The incidence of trauma increases as pregnancy progresses, which has both maternal and fetal implications. Potential maternal injuries include contusions, sprains and strains, fractures, dislocations, and poisoning, as well as life-threatening injuries. In addition to almost 1 million deaths each year, maternal trauma is associated with an increased incidence of spontaneous abortion, preterm birth, preterm premature rupture of membranes, uterine rupture, unplanned cesarean delivery, placental abruption, and fetal demise (Mendez-Figueroa et al., 2013). The gestational age at the time of injury, the type and severity of the injury, and the injury mechanism are all important considerations that impact treatment course as well as maternal and fetal outcomes. This chapter will focus primarily on noncatastrophic trauma in viable pregnancies, along with a brief discussion of catastrophic trauma including pelvic fractures, burns, electrical injuries, and maternal cardiopulmonary arrest. Exhibit 16.1 provides a general overview of the classification of trauma during pregnancy. A comprehensive review of catastrophic trauma in the pregnant patient is beyond the scope of this section.
MECHANISMS OF INJURY
The vast majority of trauma in pregnancy can be attributed to unintentional injuries, with motor vehicle collisions (MVC) being the most common cause. The incidence rate for MVCs during pregnancy is estimated to be 207 cases per 100,000 pregnancies, with close to 90% of women involved in MVCs receiving some form of medical care during pregnancy (Kvamstrand, Milsom, Lekander, Druid, & Jacobsson, 2008; Whitehead, 2011). Furthermore, MVCs are a leading cause of mortality with rates of 1.4 maternal deaths and 3.7 fetal deaths per 100,000 pregnancies, respectively (Kvamstrand et al., 2008).
While the incidence and occurrence for most mechanisms of injury are equally distributed throughout pregnancy, falls are far more common during winter months and beyond 20 weeks gestation due to pelvic laxity, weight gain, and subsequent postural imbalance. Current estimates from population-based studies suggest that one in four women will fall at least once during pregnancy (Dunning et al., 2003). A population-based prospective study evaluating pregnant women hospitalized following a fall revealed a four-fold increase in preterm 170labor, an eight-fold increase in placental abruption, and a two-fold increase in non-reassuring fetal heart rate patterns, when compared to a similarly matched control group (Schiff, 2008). Whether the primary mechanism of injury is a MVC or a mechanical fall, blunt trauma resulting in subsequent placental abruption is a common concern related to the mechanical strain placed on the gravid uterus. Abruptio placentae complicates up to 40% of pregnancies with major injuries and 3% of minor trauma with direct uterine force (Brown, 2009). Two proposed mechanisms for placental abruption in the literature are the shearing force from initial impact and the contrecoup effect that results from negative pressure within the uterus (Mendez-Figueroa et al., 2013). The premature separation of the placenta from the uterine wall results in decreased uterine blood flow, which can lead to significant fetal hypoxia and acidemia. In the most severe cases, fetal death can occur.
Classification of Trauma
• Low impact motor vehicle collision without air bag deployment
• Minor abdominal, head, neck, or back injuries without pain
• Mechanical fall without physical injuries
• Physical assault without physical injuries
• Poisoning and drug overdoses
• Victims not in major trauma category
• Cardiac or respiratory arrest
• High impact motor vehicle collision with air bag deployment
• Direct abdominal, head, neck, or back injury with associated pain
• Unresponsive or loss of consciousness
• Maternal burns involving greater than 40% body surface area
• Motor vehicle vs. pedestrian
• Penetrating injuries
• Unstable vital signs (BP <80/40 or HR <50 or >140 or fetal heart rate <110 or >160)
BP, blood pressure; HR, heart rate.
Source: Courtesy of Women & Infants Emergency Obstetrics and Gynecology Division, Providence, RI.
While uncommon, pelvic fractures in the setting of pregnancy carry a particularly high maternal and fetal morbidity given the propensity for massive intraperitoneal hemorrhage and subsequent hypovolemic shock (Mirza, Devine, & Gaddipati, 2010). Not surprisingly, both maternal and fetal outcomes are dependent on the degree and extent of the injury. In general, women who sustain minor pelvic fractures in the third trimester of pregnancy can safely attempt vaginal birth (American College of Obstetricians and Gynecologists [ACOG], 1998). The indicators that may prohibit a successful vaginal delivery include fractures that are extensive, severely dislocated, or unstable. Vaginal birth was successful in 75% of women who had suffered pelvic fractures during the latter portion of their pregnancy (Leggon, Wood, & Indeck, 2002).
171Penetrating trauma is a relatively rare occurrence during pregnancy and accounts for 9% of all trauma-related pregnancy admissions (Petrone et al., 2011). The vast majority of penetrating injuries are due to gunshots from handguns and, to a lesser extent, stab wounds from knife-related injuries. Maternal mortality is rare, occurring in less than 5% of penetrating trauma cases, and is directly related to the size of the gravid uterus in relation to other intra-abdominal organs (Leggon et al., 2002; Mirza et al., 2010). In contrast, increased hospital stay, postoperative complications, and direct fetal injury are by far more common following penetrating trauma with reported fetal mortality rates as high as 73% (Petrone et al., 2011). The management following penetrating injury is ultimately determined by the entrance location. Injury to the maternal bowel is likely with upper abdominal penetrating injuries, while lower abdominal wounds are more likely to injure the uterus and/or fetus. Of note, the appearance of the entrance wound is not predictive of the extent of internal injury (Petrone et al., 2011).
The current literature on burn injuries occurring during pregnancy is based on case reports or case series. Burns during pregnancy may occur from either electrical or thermal causes. Regardless of the cause of the burn, the pregnant state, maternal age, and trimester of pregnancy do not alter maternal survival rates. Outcomes, however, are largely dependent on the depth of the burn and total body surface area involved. When greater than 40% of the total body surface area is involved, maternal and fetal mortality rates approach 100%, largely due to sepsis (Chama & Na’Aya, 2002). Maternal and fetal mortality are also increased when direct inhalation injury occurs due to significant airway compromise and subsequent maternal and fetal hypoxia (Karimi, Momeni, & Rahbar, 2009). While data on electrical injuries during pregnancy is limited, injuries vary according to type and voltage of current, as well as its path through the body. Significant maternal injuries are uncommon but can result due to direct effects of the heat generated by the current in conjunction with associated trauma. Minor electrical shock, such as from a home appliance, does not appear to impact fetal birth weight, mode of delivery, or gestational age at the time of delivery (Einarson, Bailey, Inocencion, Ormond, & Koren, 1997).
Intentional trauma also poses significant maternal and fetal risks during pregnancy. Intimate partner violence (IPV) is the most common form of intentional trauma with prevalence rates ranging from 1% to 57% during pregnancy (Mendez-Figueroa et al., 2013). Overall, the management of domestic and sexual violence is similar to that of blunt trauma unless gunshot and/or stab wounds are involved. Sexual assault is often an underreported yet critical component to consider when a pregnant woman is also a trauma patient. Acute traumatic injuries following assault range from minor trauma to more significant injuries, including maternal and fetal death. Pregnant women who are verbally abused are more likely to deliver low-birth-weight infants, while those who are physically abused have higher rates of neonatal deaths (Yost, Bloom, McIntire, & Leveno, 2005). The overall risk of physical injury increases for women who are rape victims by a known assailant, when a weapon is involved, when the perpetrator is under the influence of drugs or alcohol, or the assault occurs in the victim’s or perpetrator’s home (ACOG, 2011).
Optimal management of the pregnant trauma victim often requires a multidisciplinary approach. While diagnostic and treatment algorithms for the 172management of catastrophic versus noncatastrophic trauma will vary, fetal outcomes following trauma in pregnancy are directly correlated with early and aggressive maternal resuscitation. Accordingly, a primary management goal when caring for any pregnant trauma victim is maternal stabilization. Following a motor vehicle accident or fall, in a pregnant woman who is stable, initial key questions to elicit are listed in Exhibit 16.2.
Key Questions to Elicit Following Motor Vehicle Accidents or Falls
• Was there any head or direct abdominal trauma?
• Did you have loss of consciousness?
• How fast were you traveling?
• Were you restrained, driver or passenger?
• Any air bag deployment?
• When is your due date?
• Do you have any contractions, vaginal bleeding, or leakage of fluid?
• Can you feel the baby move?
Source: Courtesy of Women & Infants Emergency Obstetrics and Gynecology Division, Providence, RI.
According to the National Center for Injury Prevention and Control, pregnant women greater than 20 weeks gestation must be transported to a medical center capable of performing a prompt and thorough trauma evaluation alongside management of potentially life-threatening injuries (Centers for Disease Control and Prevention, 2011).
PHYSICAL EXAMINATION AND INITIAL MANAGEMENT
Both the impact and management of blunt abdominal trauma on a developing fetus are largely dependent on gestational age at the time of injury. For example, in pregnancies during the first trimester, direct fetal or placental injury is unlikely given the protection afforded by the maternal bony pelvis (ACOG, 1998). Furthermore, in any nonviable fetus, prolonged fetal monitoring is not indicated. The only appropriate fetal intervention is expectant management. In addition to gestational age, critical factors to consider include the degree of maternal injury and mechanism of injury. Exhibit 16.3 provides guidelines for clinical management of noncatastrophic blunt abdominal trauma.
The primary goals in the initial assessment and management of an injured pregnant woman are essentially identical to those in the nonpregnant population. First steps include a vital sign assessment and a targeted trauma history, alongside stabilization and transfer to a facility with the appropriate level of care. Aortocaval compression, which can occur from supine positioning of the pregnant patient, can result in decreased venous return from the lower extremities with a subsequent drop in maternal systolic blood pressure of up to 30 mmHg and a 30% decrease in stroke volume (Rudloff, 2007). Prevention of supine hypotensive syndrome via left lateral uterine displacement is therefore essential to optimize maternal and fetal hemodynamics.