Abstract
Trauma complicates approximately 6–7% of all pregnancies and is associated with significant maternal and fetal morbidity and mortality. While the majority of trauma is minor, it is minor trauma that contributes to the majority of fetal mortality. Since virtually every organ system is affected anatomically and physiologically by pregnancy, it is important for healthcare providers who care for trauma victims to be aware of these changes. While assessment and resuscitation considers the existence of two patients, stabilization of the mother takes priority. Diagnostic and radiologic procedures should be used as indicated, with fetal exposure to radiation limited as much as possible. Management of the pregnant trauma victim requires a multidisciplinary approach in order to optimize outcome for mother and fetus. This review discusses the epidemiology, assessment and treatment of pregnant trauma patients and reviews areas where prevention efforts may be focused.
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Learning objectives
Upon completion of this activity, participants should be able to:
Describe the prevalence and risk for trauma on mother and fetus during pregnancy
Describe the optimal resuscitation position for a pregnant woman after trauma
Describe radiation risks associated with trauma during pregnancy
Identify the predictive value of the Injury Severity Score in pregnant women exposed to trauma
Describe the primary and secondary survey of the pregnant woman exposed to trauma
Financial & competing interests disclosure
The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript.
Management of the pregnant trauma victim involves the care and consideration of two patients. While optimizing the wellbeing of two patients, the health of the mother remains of paramount importance. Rapid assessment, treatment and transport are critical to optimizing maternal and fetal outcome. Evaluation must be performed with an understanding of the physiologic changes that occur in pregnancy. These changes will alter maternal response to trauma and require adaptations to care. Management requires a multidisciplinary approach involving emergency medical technicians, emergency medical physicians, trauma surgeons, anesthesiologists, obstetricians, fetomaternal medicine specialists, pediatricians, radiologists and nurses. The obstetrician has the unique ability to consider the physiologic changes of pregnancy in the context of trauma and discern what is physiologic and what is is life threatening.
General considerations
Trauma complicates 6–7% of all pregnancies and is the leading non-obstetric cause of maternal morbidity and mortality accounting for 46% of maternal deaths or more than 1 million deaths annually worldwide [1–9]. However, most traumatic injuries are minor and only 0.3–0.4% of pregnant women are admitted to the hospital [10]. Fetal death is more common than maternal death. However, actual fetal injury and fetal loss rates may be underestimated owing to a lack of standardized reporting methods; the loss occurs subsequent to the trauma at a different center; the loss occurs as a result of trauma deemed too minor to present for care; or because in some jurisdictions fetal losses at less than 20 week' gestation are not recorded [11–13]. The causes of traumatic injury in the pregnant patient reflect those of the nonpregnant population. Pregnancy itself does not increase maternal mortality from trauma, as mortality appears to be more a function of injury severity [14]. Owing to the increasing size of the uterus and fetus, the risk of trauma to the mother and fetus increases as pregnancy progresses; 10–15% in the first trimester and 50–54% in the third trimester [1]. Pregnancy appears to alter the pattern of injury, making the gravida more prone to abdominal trauma, particularly as gestation advances, and less vulnerable to head trauma [14]. The distribution of trauma includes motor vehicle accidents (55%), falls (22%), assaults (22%) and burns (1%), although the contribution of interpersonal violence may be increasing [15,16]. In a review by Connolly et al., the mean maternal age at the time of trauma was 24 years and the mean gestational age was 25.9 weeks. The average gestational age at delivery was 37 week' gestation [15]. Risk factors for trauma include young age, drug use and domestic violence [13,17–19].
Physiologic changes of pregnancy management implications
Virtually every organ system undergoes anatomic or physiologic changes and it is critical to have an appreciation of these changes when managing the pregnant trauma victim. Physiologic changes of pregnancy are presented in
Physiological changes during pregnancy.
bpm: Beats per min.
As the pregnant patient physiologically prepares for the blood loss associated with delivery, blood volume increases by 50% and there is a 30% increase in erythrocyte volume. The increase of plasma volume relative to red blood cell volume causes a physiologic anemia resulting in hematocrit values of 32–34%. The pregnant patient can hemorrhage up to 2000 ml of blood (30–40% of her blood volume) before she manifests a change in her heart rate or blood pressure, but this is followed by rapid deterioration when hemorrhage approaches 2500 ml [21]. Therefore, hypotension should be aggressively treated and the increase in blood volume should be considered when determining resuscitation needs. Cardiac output increases up to 50%, beginning in the first trimester and peaking somewhere between 20 and 30 week' gestation. Cardiac output remains at third trimester values for the first 48 h postpartum and then gradually decreases to nonpregnant values over the following 2 weeks. Uterine blood flow comprises approximately 20% of cardiac output increasing up to 600 ml/min, and can serve as a significant source of hemorrhage in the face of trauma. Uterine blood flow has no autoregulation and is, therefore, dependent on maternal mean arterial blood pressure for blood flow. The uterine vasculature is exquisitely sensitive to catecholamines and, therefore, any changes in blood pressure can negatively impact uterine blood flow, thereby compromising fetal perfusion and oxygenation. In fact, fetal distress may be the first indication of maternal hemodynamic decompensation. The enlarging uterus is capable of aortocaval compression by 20 week' gestation, which can compromise venous return to the heart and reduce cardiac output. When the pregnant woman is supine, aortocaval compression reduces cardiac output by approximately 30% and can result in maternal pallor, sweating, nausea, vomiting, hypotension, tachycardia and mental status changes. During resuscitation the patient should be tilted on her left side by placing a wedge under her right hip or using a backboard titled to a 15° angle.
Blood pressure is lower in pregnancy as a result of the vasodilatory effects of progesterone and the low-resistance, placental bed decrease in systemic vascular resistance during pregnancy. This decrease nadirs at 28 week' gestation and blood pressure gradually returns to normal at term [1]. Estrogen-mediated increases in myocardial α receptors results in an increase in heart rate [22].
Normal findings on an ECG include sinus tachycardia, ectopic beats, left axis deviation, inverted or flattened T waves, and a Q wave in cardiac leads III and AVF [23].
The increased metabolic demands of pregnancy increase oxygen consumption in the gravida. Minute ventilation increases, largely as a result of increased tidal volume, as maternal respiratory rate changes minimally. The diaphragm moves approximately 4 cm upward in pregnancy and the thoracic anteroposterior diameter increases. Therefore, when performing thoracostomy procedures, entry should be carried out one to two intercostals spaces higher to avoid injury to the diaphragm and abdominal contents. These anatomic alterations, in addition to the enlarging uterus, cause decreased expiratory reserve and residual lung volumes, thereby decreasing functional residual capacity. Decreased functional residual capacity coupled with increased oxygen consumption during pregnancy result in rapid maternal desaturation in the face of depressed respiration or apnea. Owing to the diminished oxygen reserve, oxygen should be provided to all pregnant victims and there should be early consideration for placement of an oral, nasal or endotracheal airway. Denitrogenation and preoxygenation with 100% oxygen is performed prior to intubation. Airway edema, tongue enlargement, increased breast size and generalized weight gain of pregnancy make laryngoscopy and intubation difficult [7]. The hyperemic mucosa and oropharynx predispose to bleeding with manipulation, further compromising an already challenging airway.
Normal chest x-ray findings in a pregnant patient include mild cardiomegaly, a widened mediastinum, an increased anteroposterior diameter and prominence of the pulmonary vasculature [1,3]. The pregnant woman exists in a state of mild respiratory alkalosis. Elevated progesterone levels act on the medullary respiratory center stimulating ventilatory drive causing a decrease in PaCO2 values. Since values are lower in pregnancy, a PaCO2 value in the nonpregnant range is concerning. There is a compensatory renal excretion of bicarbonate, thereby maintaining an arterial pH of 7.40–7.45. The increased minute ventilation results in PaO2 levels that are higher than nonpregnant values. Maternal oxygen saturation should be maintained at 95% in order to maintain a PaO2 greater than 70 mmHg, thereby optimizing oxygen diffusion across the placenta. Fetal oxygenation is maintained when maternal PaO2 remains higher than 60–70 mmHg. When it falls below this level, fetal oxygenation is immediately compromised.
The smooth muscle relaxation effects of progesterone contribute to decreased gastric tone and motility and reduced lower esophageal sphincter tone. In addition to the cephalad displacement of the stomach and increased gastric acid production, smooth muscle relaxation results in an increased risk of aspiration when the trauma victim is unable to protect her airway. Gradual growth and distention of the peritoneum as the uterus expands appear to desensitize the pregnant patient to peritoneal injury. Therefore, abdominal tenderness, rebound and guarding may not be present upon physical examination. Normal pregnancy complaints include nausea, vomiting and abdominal pain, symptoms that can confound the exam of a trauma patient.
Venous pooling in the lower extremities can lead to more extensive blood loss with lower extremity injuries and can predispose to deep venous thrombosis. The increased engorgement of pelvic vessels associated with pregnancy places the patient at an increased risk of retroperitoneal hemorrhage and hematomas following lower abdominal and pelvic trauma [2]. The use of saphenous and femoral veins are less preferred for medication administration since venocaval compression by the gravid uterus inhibits venous return and compromises effective drug delivery. However, in an emergency, access is possible if necessary. In order to prevent obstetric hemorrhage, most procoagulant factors are increased during pregnancy. This may be beneficial for the trauma patient in achieving hemostasis after injury. Fibrinogen levels are normally higher in pregnancy, so findings of a normal or low fibrinogen level, in addition to elevated fibrin degradation products and low platelets, suggest disseminated intravascular coagulation. An increase in procoagulants, in addition to venous stasis and endothelial damage, place the gravida at risk for thromboembolic complications including pulmonary embolism. Therefore, thromboembolic prophylaxis with heparin, pneumatic compression devices and early ambulation when possible should be considered.
Diagnostic radiation
In the face of trauma, all indicated tests must be performed, including diagnostic radiologic studies. Diagnostic studies should be obtained for indications similar to that in the nonpregnant patient, but studies should be limited and the uterus shielded whenever possible. Radiation risk to the fetus is determined by gestational age, type of study, proximity to the uterus, use of uterine shielding and type of machine used [1,3]. The unshielded fetus receives approximately 30% of the radiation to that which the mother is exposed. Fetal risks from radiation are greatest during the period of major organogenesis, which is between 2 and 7 weeks postconception. The fetal CNS is vulnerable between 8 and 15 week' gestation. Radiation carries negligible fetal risk of anomalies after 20 week' gestation, especially if cumulative doses are less than 10 rads (100 mGy). Radiation doses of less than 1 rad (10 mGy) are believed to contribute little to fetal risk. Radiation doses of less than 5 rads (50 mGy) are not associated with an increase in pregnancy loss or fetal anomalies [24]. Exposures to 15 rads (150 mGy) are associated with a 6% chance of mental retardation, 3% chance of childhood cancer and a 15% chance of microcephaly [25]. Computed tomography (CT) imaging is an excellent modality for evaluating for internal and intrauterine injuries and hemorrhage. Head and chest CT imaging exposes the fetus to far less radiation, particularly with uterine shielding, and may be used with little fetal exposure risk [3]. The approximate fetal radiation exposure for certain radiologic studies is presented in
Approximate fetal radiation exposure based on study mrad-millirad.
Values listed in the table are with shielding except where the fetus is necessarily in the field.
Focused abdominal sonography for trauma (FAST) is used to assess for free fluid in the pericardial and pleural cavities, and in the peritoneum and retroperitoneum.
This study has a sensitivity and specificity of 85 and 99%, respectively, for detection of intraperitoneal fluid and a sensitivity and specificity of 100 and 99%, repestively, for detection of pericardial fluid [26].
Ultrasound may also be used to confirm fetal heart rate, assess gestational age, evaluate for possible placenta previa or abruption and to assess fetal wellbeing [20,27]. Using ultrasound whenever possible avoids exposing the fetus to ionizing radiation. While the sensitivity of identifying abruption with ultrasound is poor (less than 50%), it has a high positive predictive value [28,29].
Fetomaternal outcomes
While life-threatening injuries as a result of trauma account for less than 8% of total trauma, it is associated with a 40–50% risk of fetal loss. While 24 week' gestation is considered the accepted standard for viability, it is a parameter that is locally defined and dependent on the available resuscitative capabilities. Furthermore, differences exist between viability (ability to live outside of the uterus) and intact viability (survival without significant neurologic morbidity). As the threshold of viability has decreased, it has been associated with decreases in intact survival. Perinatal morbidity and mortality is also impacted by nature of the trauma, gestational age, availability of neonatal resuscitation and exposure to antenatal steroids. While fetal loss is much less common with mild injuries (1–5%) compared with life-threatening trauma, since minor injuries occur so much more frequently they account for the majority of fetal losses [20]. Situations where fetal death occurs include motor vehicle accidents (82%), gunshot wounds (6%) and falls (3%), with maternal death accounting for 11% of fetal deaths [20,30]. The injury severity score is associated with the fetomaternal morbidity and mortality resulting from trauma. Six body regions are assigned scores after which the highest three scores are squared and summed. The higher the score the greater the maternal risk of morbidity and mortality. A score of 0 indicates no injury and scores greater than 16 indicate severe injury. A score of more than 9 has a sensitivity and specificity of 85.7 and 70.9%, respectively, for predicting fetal death [31]. Other predictors of fetal death include pelvic fractures (25–57% mortality), high maternal-base deficit, low serum bicarbonate, high abdominal- or thoracic-abbreviated injury score, direct fetal or uterine injury, fetal heart rate abnormalities, uterine activity, early gestational age, maternal coma and death [14,20,32,33]. Fetal death may be a result of placental abruption, direct fetal injury, maternal shock, hypoxia, disseminated intravascular coagulation and unexplained reasons [34,35].
Blunt trauma
Pregnant women are more likely than nonpregnant women to sustain abdominal trauma [3]. Blunt trauma may be the result of motor vehicle accidents, pedestrian automobile accidents, falls, direct abdominal trauma and assault. Motor vehicle accidents are the leading cause of maternal blunt trauma and account for 55–82% of maternal trauma [1–3]. Blunt abdominal trauma is associated with a 3–38% incidence of fetal mortality. Direct fetal injury is uncommon with blunt trauma. This is owing to the absorption of forces by the uterus, placenta and amniotic fluid. Fetal injury and death is more a indirect result. The most common cause of fetal death is maternal shock and death [3]. When the mother survives, abruption is the next leading cause of fetal mortality followed by uterine rupture [36,37].
The peritoneal pain threshold increases with advancing pregnancy, which, in addition to pain referral to atypical areas as a result of intra-abdominal organ displacement, confounds the physical examination. Prior to approximately 13 week' gestation, the uterus has not yet become an abdominal organ and is protected by the body pelvis [20]. Fetal loss in the first trimester is less likely to be the result of direct trauma (occurring less than 1% of the time), but rather due to uterine hypoperfusion resulting from maternal hypotension or death [20]. As the uterus enlarges, it displaces the bowel cephalad, thereby protecting these structures; however, this renders the fetus more vulnerable to injury [2]. Thinning of the uterine wall with growth and the relative decrease in amniotic fluid volume also contribute to fetal vulnerability.
Since the bladder cephalad is displaced by the enlarging uterus making it susceptible to injury, hematuria after injury should be aggressively evaluated [1]. Splenic injuries occur most commonly in the third trimester and may occur even after apparently mild trauma. Injury to the spleen and retroperitoneal bleeds are the most common injuries resulting from blunt trauma, and splenic injury is the most common cause of intraperitoneal hemorrhage [28]. Engorgement of the spleen renders it vulnerable to injury and excessive blood loss [1]. Injuries to the liver or spleen may result in abdominal pain, shoulder pain and elevated transaminases [1].
Pelvic fractures are commonly associated with blunt trauma and are associated with significant retroperitoneal hemorrhage as a result of the myriad of engorged pelvic vessels. A review by Leggon et al. found the overall maternal mortality resulting from pelvic fractures to be 9% with a 35% fetal mortality. Maternal deaths were commonly a result of associated injuries and hemorrhage [38]. Pelvic fractures are the most common trauma resulting in direct fetal injury manifest by skull fractures and brain injury, particularly when the head is engaged in the pelvis. Fetal mortality can approach 25% in these cases [2]. Often, pelvic fractures are associated with injuries to the bladder, urethra and rectosigmoid colon. Pelvic x-rays must be interpreted with caution since there is a normal widening of the sacroiliac joints and symphysis pubis with pregnancy. Pelvic fracture is not necessarily a contraindication to vaginal delivery unless it is unstable.
Obstetric complications of blunt abdominal trauma include preterm labor, preterm delivery, preterm premature rupture of membranes, abruption, fetomaternal hemorrhage, and rarely, uterine rupture.
Preterm labor & delivery
Premature labor complicates 25% of trauma cases after 22–24 week' gestation. Most preterm deliveries occur remote from the trauma. Preterm labor is managed using standard obstetric protocols. Common tocolytics include calcium-channel blockers, magnesium sulfate and nonsteroidal anti-inflammatory agents.
Calcium-channel blockers, such as nifedipine, are commonly used ‘off-label’ as tocolytics for preterm labor. They act by inhibiting the influx of calcium ions through the voltage-dependent channels of smooth muscle, thereby decreasing intracellular calcium and decreasing calcium release from intracellular stores. When compared with other tocolytics, nifedipine has fewer side effects. Maternal side effects include flushing and headache, largely as a result of hypotension. As nifedipine can cause tachycardia and hypotension, care should be taken when administering this medication in a trauma victim since this may exacerbate an already potentially falling blood pressure. Magnesium sulfate is a commonly used, parenterally administered tocolytic. While its exact mechanism of action remains unclear, it probably competes with calcium at the level of the motor endplate or at the plasma membrane voltage-dependent channels. By competing with intracellular calcium, myosin light-chain kinase activity is inhibited. Maternal side effects include flushing, headache, nausea, vomiting, lethargy, diplopia and muscle weakness. Since magnesium sulfate is renally excreted, careful attention must be paid to urine output, as oliguria may result in toxic levels, causing respiratory depression and cardiac arrest.
Nonsteroidal anti-inflammatory medications, such as indocin, act to inhibit the actions of prostaglandins. They do this by inhibiting conversion of arachadonic acid to prostaglandin G2. Prostaglandins act to increase free intracellular calcium in myometrial cells and increase myosin light chain kinase activity, thereby causing uterine contractions. Maternal side effects are primarily gastrointestinal; however, prolonged use may result in adverse fetal effects such as premature closure of the ductus arteriosus, oligohydramnios and neonatal pulmonary hypertension.
Abruption
Abruption occurs with 1–5% of minor injuries and 2–50% of major life-threatening injuries and has a higher prevalence in women suffering trauma compared with the general obstetric population [28,36,39,40]. Alongside maternal death, abruption is the most frequent cause of fetal death from trauma [7]. Abruption occurs when acceleration–deceleration injuries result in shearing forces that separate the relatively elastic myometrium from the inelastic placenta [1,7]. Placental injury results in the release of thromboplastin into the circulation and uterine injury releases plasminogen activator resulting in fibrinolyisis. These processes can lead to disseminated intravascular coagulation. The patient may complain of abdominal pain, bleeding and/or back pain. Examination may demonstrate vaginal bleeding and a tender, rigid uterus. Pregnancy-related morbidity is associated most with vaginal bleeding, uterine tenderness and/or uterine contractions [39]. Significant direct abdominal trauma, abdominal or uterine tenderness or vaginal bleeding suggest placental abruption and requires evaluation. The patient should be admitted and continuous fetal monitoring initiated if the fetus is considered viable. At a minimum, a complete blood count, fibrinogen, blood type and Kleihauer–Betke should be obtained. Electronic fetal monitoring is the most sensitive tool in identifying abruption. In a study by Pearlman et al., patients with uterine contractions demonstrated a 20% risk of placental abruption [28]. Cardiotocography has demonstrated a 100% negative predictive value for adverse outcomes when monitoring was reassuring and there were no significant early clinical findings. Initial external fetal monitoring for 2–6 h is recommended for all patients of 20 week' gestation with any multisystem or minor abdominal trauma. Monitoring should be continued if there is evidence of persistent contractions, uterine tenderness, vaginal bleeding, significant maternal injury, rupture of membranes or a nonreassuring fetal heart rate pattern [3]. Monitoring may be discontinued and the patient discharged if laboratory evaluation is normal, the fetal tracing is reassuring, contraction frequency is less than one per 10 min, and there is no evidence of vaginal bleeding or nonreassuring maternal status. Rhogam should be given prior to discharge in Rhesus (Rh)-negative patients.
Uterine rupture
Uterine rupture occurs in less than 1% of patients suffering blunt abdominal trauma and usually occurs as a result of direct abdominal trauma to a woman who has a uterine scar. In those women with an unscarred uterus, rupture tends to occur in the posterior aspect of the uterus. Uterine rupture is associated with a maternal mortality of approximately 10%, but with a fetal mortality approaching 100% unless immediate action toward delivery is taken [41].
Fetomaternal hemorrhage
Fetomaternal hemorrhage occurs in 10–30% of pregnant trauma patients [42]. It occurs more commonly in women who suffer abdominal trauma with an anterior placenta and/or experience uterine tenderness [43]. Fetal risks of fetomaternal hemorrhage include anemia, arrhythmias and exsanguination with resultant fetal distress and death [28]. Maternal risks include Rh sensitization. Less than 1 ml of Rh-positive fetal blood can result in sensitization in an Rh-negative woman.
The Kleihauer–Betke blood test assesses for hemorrhage of fetal cells into maternal circulation. It allows for quantification of the amount of fetal red blood cells that have been introduced into the maternal bloodstream. All Rh-negative pregnant trauma victims should receive 300 μg of Rh-immune globulin within the first 72 h of fetomaternal hemorrhage and another 300 μg for each additional 30 ml of estimated fetal blood identified in the maternal circulation [12]. A positive Kleihauer–Betke test has been associated with preterm contractions suggesting a need for prolonged monitoring in patients with a positive test [44]. In circumstances of massive fetomaternal hemorrhage, an antibody screen should be repeated in 48–72 h after the administration of Rhogam. A negative result suggests the need for additional Rhogam.
Seatbelts
Approximately 46–74% of pregnant trauma patients are restrained during motor vehicle accidents [3,20,45]. Poor compliance with restraint use may be due to maternal concerns that seatbelt use can harm the pregnancy [20]. When trauma is the result of motor vehicle accidents, Crosby et al. found that among unrestrained women who were ejected, the maternal mortality rate was 33% with a 47% fetal mortality rate. They found that while there is no evidence that seatbelt use in pregnancy decreases overall maternal mortality, there is an increase in mortality in mothers ejected from the vehicle. Therefore, they recommended that women wear seatbelts to prevent ejection-associated mortality [37]. The use of restraints is associated with reduced injury severity, thereby also reducing risk of fetal demise [45].
The American College of Obstetricians and Gynecologists and the National Highway Traffic Safety Administration recommend that seatbelts be placed as low as possible over the protuberant portion of the abdomen, across the thighs, and the shoulder strap to the side of the uterus between the breasts and over the midportion of the clavicle [2,24]. An improperly placed seatbelt may result in uterine rupture and fetal demise [46]. While fetal injury with airbag deployment has been described, the National Highway Traffic Safety Administration does not consider pregnancy as an indication to inactivate airbags. However, the woman should position herself at least 10 inches back from the center of the airbag cover [47,48].
Falls
Falls account for 3–31% of maternal injuries [1,15]. The morbidity associated with falls is modest, and is typically associated with less than a 10% incidence of maternal or fetal complications [49].
Falls occur more commonly in the third trimester than at any other time in pregnancy [50]. The gravid female has an increase in spinal lordosis that allows for shifting of her center of gravity over her legs [1]. This change in the center of gravity contributes to more falls as pregnancy progresses. When patients fall, they fall primarily on their buttocks, side or onto their abdomen. The most common injuries identified in hospitalized pregnant women are fractures and these typically occur in the lower extremity. Other injuries include bruises, cuts, ankle sprains and strains. Associated complications include preterm labor, abruption, uterine rupture, low birthweight and stillbirths [1]. Fractures to the lower extremity also increase the risk of thromboembolic events [51].
Assault
Approximately 1 million women sustain nonfatal violence by an intimate partner annually and at least 1400 women die as a result [1,52]. The prevalence of domestic violence ranges from 10 to 30% and is associated with a 5% risk of fetal death [3,20,53]. Abused pregnant women have a three-fold higher risk of being victims of attempted and completed homicide than non-abused controls [54]. Most often, the abuser is the patient's boyfriend or spouse. Interpersonal violence is not associated with marital status, age, race or socioeconomic status. Risk factors for domestic violence include reproductive age and alcohol and substance abuse [55,56]. As the pregnancy advances, the violence may escalate in incidence and severity and the uterus and fetus may sustain the brunt of the force [42,43,54]. Common sites of abuse include the face, head, breasts, abdomen upper arm and lateral thighs. Assault is associated with delay in prenatal care, fetal death, low fetal birthweight, low maternal weight gain, maternal infections, anemia, preterm labor, preterm premature rupture of membranes and abruption [54,57,58]. Depression is more common in victims of domestic violence and victims are more likely to attempt suicide [59].
Penetrating trauma
Penetrating trauma comprises approximately 3–10% of maternal trauma [13,60]. Penetrating trauma is primarily the result of gunshot wounds followed by knife wounds, the former of which is more lethal for the mother and fetus. Maternal mortality occurs in fewer than 5% of cases of penetrating trauma. The incidence of visceral injury with penetrating trauma in pregnancy is 16–38% compared with 80–90% in the nonpregnant population [61]. Gunshot wounds to the abdomen result in fetal injury in up to 70% of cases and 40–70% of these fetuses die [20,62]. Fetal death is the result of direct fetal injury or preterm delivery [61]. The density of the uterus will rapidly dissipate the energy of a low velocity projectile but high velocity missiles are far more devastating to the mother and fetus. In early pregnancy the uterus is dense and protects the fetus and viscera. This contributes to fairly low incidences of maternal visceral injury and improved maternal outcomes. As pregnancy advances, the enlarging uterus displaces the abdominal contents cephalad and cushions against penetrating injury. However, this leaves the uterus vulnerable to penetrating trauma and renders abdominal contents vulnerable with upper abdominal wounds. With respect to knife wounds, location of the injury is a critical determinant of outcome. Upper abdominal stab wounds can result in more complex bowel injury due to its upward displacement [20]. Therefore, upper abdominal injuries are often surgically managed [3,63].
Treatment guidelines are similar to those for nonpregnant patients and include management options, such as immediate surgical exploration and removal of the foreign object, diagnostic peritoneal lavage, laparoscopy, CT imaging, local wound exploration and observation. Radiographic studies are helpful in localizing a bullet that has not exited. Management is often individualized and should involve a multidisciplinary team including trauma surgeons and obstetricians [3]. Laparotomy is typically performed for the management of gunshot wounds to the abdomen; however, selective laparotomy may be considered and surgery limited to those patients where vital signs are unstable, entry site is anterior and subfundal and when diagnostic imaging indicates that the missile has not exited the posterior uterine wall. Patients should receive antibiotics to cover streptococcal and clostridium infections. Management in an intensive care setting with continuous fetal monitoring and serial evaluations is recommended.
Burns
The incidence of burns in pregnancy is relatively low and actually difficult to determine. Approximately 7% of women of reproductive age are presented for burn treatment annually [64]. Maternal and fetal mortality are directly related to the type, location and severity of the burn sustained, in addition to the presence of complications. Fetal outcome is also related to gestational age. The rate of fetal loss is approximately 56% when patients sustain burns over 15–25% of their body surface area [1]. Fetal mortality is as high as 63% when body surface area is 25–50% and approaches 100% when burns cover greater than 50% of total body surface area [65,66]. Maternal and fetal deaths are often a result of inadequate fluid resuscitation, prolonged hypotension, shock, hypoxia, septicemia and hyponatremia [1]. Burn severity is determined by the depth and size of the burn. When caring for the pregnant burn patient, one should consider the potential for carbon monoxide poisoning. Carbon monoxide crosses the placenta and preferentially binds with fetal hemoglobin, creating fetal carboxyhemoglobin. Carboxyhemoglobin levels should be evaluated and oxygen therapy given when levels are abnormal.
Electrocution is an infrequent cause of burns and injury in pregnancy. The majority of electric shock cases are of low voltage resulting in little adverse outcome. The degree of injury depends on the strength of the voltage, the resistance of tissue through which it passes, the pathway through which the voltage passes, duration of contact and maternal bodyweight. Electrical current is the most significant predictor of pregnancy outcome. The spectrum of injury ranges from an unpleasant maternal sensation and no fetal effects to muscle contractions, tissue damage and cardiac defibrillation resulting in arrest. Electric current passing through the uterus often involves the fetus and results in demise. Demise may occur immediately or days subsequent to the exposure. Therefore, all women experiencing electrocution of any degree should seek evaluation. Fetal heart monitoring is indicated in all gestations over 20 weeks. Other described adverse fetal effects include miscarriage and growth restriction [66–69].
Burns are managed aggressively using treatment protocols for nonpregnant victims. When trauma occurs in conjunction with burns, trauma care will take precedence [70]. Early prompt resuscitation and transport are critical. Resuscitation includes assessment of burn severity, assessment for other injuries, airway protection and oxygenation and pain management. Aggressive hydration is critical. Fluid loss and uteroplacental hypoperfusion are most likely to occur within the first 12 h following a burn [3,71]. Hydration protocols are used to estimate fluid replacement requirements [70]. Volume requirements may be greater, since protocols are often derived from nonpregnant victims. Wound care practice is similar to that of nonpregnant patients and involves early, careful eschar debridement and cleaning of burned areas to improve healing [72]. Decisions regarding delivery involve consideration of gestational age and fetal wellbeing. Urgent delivery has been considered the treatment of choice in term or near-term pregnant women with extensive burn injury [73].
Initial assessment
Late second-trimester or third-trimester pregnancy is an indication for transport to a level 1 trauma center [3]. Prehospital findings of tachycardia (defined as a heart rate greater than 110 beats/min), chest pain, loss of consciousness and third trimester have been independently associated with the need for care in a trauma center [3,27]. The guidelines for advanced trauma life support and prehospital trauma care of the pregnant patient are similar to those for nonpregnant patients. Life-saving interventions should be undertaken irrespective of pregnancy status, including any medications or diagnostic imaging. Extrication procedures are similar to those used for nonpregnant victims. The physical examination is identical to that for any trauma patient with consideration given to any pregnancy-related findings. Initial assessment involves the airway, breathing and circulation management and is focused on achieving maternal cardiopulmonary stability. Evaluation and management requires a multidisciplinary approach, with trauma surgeons and obstetricians collaborating with fetomaternal medicine specialists, emergency medical technicians, emergency room physicians and nurses, anesthesiologists and pediatricians.
Primary survey
While maintaining inline cervical spine immobilization, the airway is assessed and rendered free from obstruction and secretions [1]. The patient's head should be maintained in a neutral position if there is concern for a cervical spine injury. The respiratory rate and effort should be assessed and pulse oximetry applied. The central and peripheral pulse quality, skin color, skin temperature and capillary refill should be evaluated.
The disability and neurologic function should be assesed by performing a basic neurologic exam [1]. Eclampsia should be considered as a cause for altered mental status or seizures. The Glasgow Coma Scale is used to evaluate neurologic status. Patients with a score of 8 or less typically require intubation and mechanical ventilation for control of the airway or intracranial pressure control [7].
While maintaining cervical spine immobilization, the patient should be exposed and evaluated for any missed injuries. It is important to search for any gunshot entry or exit wounds.
Secondary survey
The secondary survey is a head-to-toe comprehensive inspection with palpation and auscultation. Evaluation of the fetus should take place only after stabilization of the mother.
Information should be obtained regarding the mechanism of injury, and regarding weapons used, use of drugs or alcohol and use of seatbelts. It is essential to obtain a complete past medical and obstetric history to include last menstrual period, current and past pregnancy complications and estimated gestational age.
The fetus may be considered viable if the fundus can be palpated between the umbilicus and the xiphoid process. Assess fetal heart tones as soon as possible during the secondary survey. Normal baseline fetal heart rate ranges from 120 to 160 beats/min. Fetal heart tones can be auscultated with a stethoscope after 20 week' gestation and using a Doppler ultrasound at 10–14 week' gestation. Continuous monitoring should be initiated if the fetus is considered to be viable. The fetal monitoring tracing should be evaluated by providers who are skilled in heart rate tracing interpretation. Fetal compromise may be manifest by tachycardia, bradycardia, loss of beat-to-beat variability or recurrent decelerations. Monitoring can also assess for uterine irritability or contractions that may not be perceived by the patient.
It is critical to pay close attention to the abdominal component of the secondary survey, as the protuberant abdomen is more vulnerable to injury. The patient should be checked for ecchymoses and asymmetry. The uterine size should be assessed in order to help determine gestational age and any signs of contractions, rigidity or tenderness should be made wary of. The distance of the uterine fundus from the pubic symphysis measured in centimeters correlates with gestational age [3].
A sterile speculum vaginal examination is performed to assess for evidence of rupture of membranes and to evaluate vaginal bleeding. Vaginal bleeding may indicate preterm labor, abruption, uterine rupture or pelvic fracture with vaginal involvement. A digital cervical exam is performed to assess for cervical dilation and effacement; however, should be deferred in the presence of bleeding until the possibility of placenta previa is eliminated. A rectal exam is performed to evaluate for hematomas and blood.
A pregnancy test should be obtained in all female trauma victims of reproductive age. Initial laboratory studies should assess hemoglobin and studies sent for immediate packed red blood cell cross-matching. Comparison of the hematocrit with prenatally obtained levels can help determine if blood loss is present or significant. Coagulation studies and a urinalysis are also obtained. Kleihauer-Betke testing is obtained when indicated. Arterial blood gases with serum bicarbonate or lactate levels may also be indicated when there is significant trauma. Toxicology testing may also be indicated since this may be positive up to 16% of the time [35].
Diagnostic studies should be obtained for indications similar to that in the nonpregnant patient but should be limited if possible. This includes cervical spine imaging, computer tomography studies, and chest and pelvic x-rays. The uterus should be shielded whenever possible.
Diagnostic peritoneal lavage may be indicated if there are abdominal signs or symptoms suggestive of intraperitoneal bleeding, altered mental status, unexplained shock, multiple abdominal, thoracic or orthopedic injuries or where FAST exam is equivocal [57]. While this may be performed earlier in pregnancy, it becomes technically more challenging as pregnancy progresses. The supraumbilical approach is used when the uterus is palpated above the pubic symphysis and is performed using an open or minilaparotomy technique in order to minimize complications such as inadvertent uterine or fetal injury.
Management
When managing the pregnant trauma patient, it is important to consider that there are two patients. However, maternal wellbeing and stability takes precedence. High-flow oxygen should be administered initially by either nasal cannula or face mask. Owing to diminished maternal oxygen reserve, when assessing breathing and the airway, there should be early consideration for placement of an oral or nasal airway or performing endotracheal or nasotracheal intubation [1]. Early intubation will protect the airway to prevent aspiration. When intubating a pregnant trauma patient, assume she has a full stomach and a cervical spine injury. This will require lifting the chin and thrusting the jaw forward. Early intubation is also recommended as developing airway edema can compromise an already challenging maternal airway. Nasopharyngeal airways are not recommended if there is facial trauma. Intubation and placement of airways should be undertaken with care and caution. In the patient with a cervical spine injury, direct laryngoscopy should be avoided and fiberoptic or awake fiberoptic intubation performed. Intubation is accomplished with a rapid sequence induction and application of cricoid pressure. Since placental production of pseudocholinesterase increases levels in pregnancy, lower doses of succinylcholine are required [74]. Both depolarizing and nondepolarizing agents cross the placenta and may result in an initially depressed neonate. After establishing an airway, high-flow 100% oxygen is administered. Placement of a nasogastric or orogastric tube may be required to evacuate gastric contents and minimize aspiration risk.
Aggressive fluid resuscitation in the pregnant trauma victim is critical and should be accomplished with placement of two large bore intravenous lines. Between 1 and 2 l of warm crystalloid should be infused immediately to replace volume. Fluids are given in a 3:1 ratio for the estimated blood loss. If indicated, transfusion with type and cross-matched packed red blood cells is preferred. However, in emergent circumstances, type O, Rh-negative blood is used. Since vasoporessors compromise uteroplacental perfusion, it is preferable to replace volume in order to manage cardiac output and blood pressure [75]. However, pressors may be required as a life-saving intervention. Norepinephrine and epinephrine restore maternal blood pressure but compromise uterine perfusion. Ephedrine and mephentermine increase maternal blood pressure while preserving uterine blood flow. Dopamine at doses no greater than 5 μg/kg per minute also raises maternal blood pressure without compromising uterine blood flow.
The patient should be tilted on her left side by placing a wedge (towels or blankets) under her right hip or using a backboard tilted to a 15° angle. This displaces the uterus laterally, thereby maximizing cardiac preload and cardiac output. Displacing the uterus laterally can increase cardiac output by 30% [1]. This is of particular importance in pregnancies beyond 20 week' gestation. In the event of possible spinal injury the uterus may be manually displaced or a backboard used.
A foley catheter is inserted for accurate urinary output assessment. Lack of urine output after catheter placement may be the result of misplacement, recent urination, incontinence, depleted intravascular volume with compromised renal blood flow or bladder rupture.
Knives and other penetrating objects should not be removed and should be stabilized in place with packing. This allows for exploration of the exact injury pathway when the patient is taken to surgery and allows for control of hemorrhage as the object provides some tamponade of bleeding [1].
When performing exploratory laparotomy with a living fetus in utero, it is imperative to handle the uterus gently and avoid applying excessive traction or twisting, which could compromise uteroplacental perfusion. Exploratory laparotomy is not an indication for cesarean delivery and is rarely indicated unless there is fetal death or direct perforating injury to the fetus. In the circumstance of fetal death, it is best to deliver the fetus by induction rather than through a hysterotomy.
When performing exploratory laparotomy, appropriate antibiotic coverage should be administered to cover for Streptococcus, Staphylococcus, Clostridium and polymicrobial infections.
For patients with penetrating injuries, tetanus toxoid administration is not contraindicated. Patients should receive 0.5 ml of tetanus toxoid if they have not received a booster in the past 5 years. They should receive 500 units of tetanus immunoglobulin intramuscularly in addition to the tetanus toxoid if they have not been immunized and have suffered a high-risk injury [1].
Special considerations Cesarean delivery
Emergency cesarean deliveries are occasionally performed for maternal or fetal indications [1]. Emergency cesarean is indicated in situations where the uterus interferes in trauma-related surgical interventions, cardiopulmonary resuscitation has been unsuccessful after 4 min, there is fetal compromise in a viable fetus with a stable mother, or there is obvious impending or recent maternal death [76,77]. Fetal and maternal survival rates after emergency cesarean delivery at greater than 25 week' gestation have been documented to be as high as 45 and 72%, respectively. There was no fetal survival when no fetal heart beat was heard before emergent delivery, whereas there was 75% survival when fetal heart tones were present and gestational age was greater than or equal to 26 week' gestation [67]. Katz et al. looked at 61 infants born to women by perimortem cesarean delivery from 1900 to 1985. They found that 70% of neonates delivered within 5 min of maternal death survived and all survived neurologically intact. When cesarean delivery was delayed greater than 5 min, only 13% of infants were living and all had neurologic morbidity. The degree of neurologic handicap correlated with time between maternal death and delivery [76].
Executive summary
Virtually every organ system undergoes anatomic or physiologic changes to adapt to the demands of pregnancy.
These physiologic changes can alter or mimic maternal response to trauma, thereby confounding evaluation.
Indicated imaging studies should be performed regardless of pregnancy, with shielding of the abdomen provided when possible.
Imaging studies not employing ionizing radiation should be used whenever possible.
The majority of traumatic injuries in pregnancy are minor; however, the majority of fetal losses are a result of minor injury. This is a result of the larger proportion of pregnant women sustaining minor injury.
Fetal death results primarily from maternal death followed by abruption.
Blunt trauma is the most common result of motor vehicle accidents followed by falls and assault.
Blunt trauma may result in preterm labor, abruption and fetomaternal hemorrhage.
Fetal monitoring should be performed for 2–6 h in any pregnancy considered to be viable.
Rh negative mothers should receive Rh-immune globulin to reduce the risk of isoimmunization.
Late second-trimester and third-trimester pregnancy is an indication for transport to a level 1 trauma center.
When managing the pregnant trauma patient, it is important to consider that there are two patients. However, maternal wellbeing and stability takes precedence.
Initial resuscitation of the pregnant trauma patient involves the basic life-sustaining measures used for the nonpregnant victim, starting with the airway, breathing and circulation management.
When managing a female trauma victim, the possibility of pregnancy should always be considered and a pregnancy test obtained.
The patient should be tilted on her left side in order to maximize cardiac output.
The evaluation and management of a pregnant trauma victim requires a multidisciplinary approach, involving trauma surgeons and obstetricians collaborating with maternal–fetal medicine specialists, emergency medical technicians, emergency room physicians and nurses, anesthesiologists and pediatricians.
Routine cesarean delivery is not warranted but should be considered in situations of fetal distress or if the presence of the fetus compromises maternal stability.
Cesarean delivery should be performed if the patient has not responded after 4 min of cardiopulmonary resuscitation and the fetus is believed to be at a viable gestational age.
Prenatal care should incorporate education on seatbelt use.
Patients should be educated about the adverse effects of alcohol and substance abuse with pregnancy.
Patient interactions should include screening for domestic violence and interventions should be provided when indicated.
Emergency rooms and trauma centers should have protocols and algorithms in place specific to the pregnant trauma victim.
Establishment of standardized reporting systems across all jurisdictions will allow for improved data collection and more accurate maternal and fetal outcome statistics.
In a follow-up review of 38 perimortem cesarean deliveries, 34 infants survived, seven of which were delivered more than 15 min after maternal cardiac arrest. The authors, acknowledging the large selection bias of their data, concluded 20 years following the initial review, that perimortem cesarean delivery within 4 min of maternal cardiac arrest improves both maternal and neonatal outcomes.
Based on these studies, it has been recommended that cesarean delivery be performed if the patient has not responded after 4 min of resuscitation. A total of 4 min of resuscitation and 1 min to deliver the neonate is the basis for the ‘5-min rule’. One may want to consider proceeding with delivery even if resuscitation efforts have extended beyond 4 min as neonatal survival has been described. In addition to optimizing fetal outcome, cesarean delivery removes aortocaval compression, resulting in a 60–80% increase in cardiac output, and eliminates the low-resistance placental bed, thereby improving maternal chances for survival.
Cardiac arrest
Cardiac arrest during pregnancy is rare, occurring in approximately one in 30,000 pregnancies. Prompt initiation of cardiopulmonary resuscitation is critical while addressing the underlying etiology for the arrest [1]. Standard advanced cardiac life support algorithms for medications, intubation and defibrillation are applied. Chest compressions and ventilations are performed in the usual manner; however, they are less effective in the latter trimesters owing to aortocaval compression compromising cardiac output. Resuscitation is performed with the patient in the lateral decubitus position. Moving the hand position cephalad improves compressions as the heart is displaced upward during pregnancy. Defibrillatory shocks transfer no significant current to the fetus. A decision to move toward cesarean delivery should be made quickly, with delivery of the fetus accomplished within 5 min of the cardiopulmonary arrest [76].
Future perspective
Of paramount importance in managing trauma in pregnancy is preventing its occurrence in the first place. Education in trauma prevention should be incorporated into prenatal care, and should include instruction on the appropriate use of seatbelts, encouraging their use and addressing the misconceptions that using them may somehow harm the fetus. Outpatient visits, whether for a prenatal visit or other reasons, should incorporate screening for domestic violence, screening that is best performed with the patient alone. Healthcare providers have the opportunity to identify women at risk for domestic violence and provide the necessary support and counseling and legal referrals.
Patients should be educated about the adverse effects of alcohol and substance abuse with pregnancy and should be referred to counseling or provided with social services when indicated.
It is important to appreciate that pregnancy loss can occur even in patients with minor or no injuries. Healthcare providers must not assume that minimal maternal injury confers no fetal risk. Therefore, all pregnant women should be advised to seek medical attention after trauma, regardless of how minor the trauma is perceived to be. Emergency rooms and trauma centers should have protocols and algorithms in place specific to the pregnant trauma victim. Establishment of obstetric injury severity scoring systems may provide improved prognostication of fetal and maternal outcomes. Furthermore, the establishment of standardized reporting systems across all jurisdictions will allow for improved data collection and more accurate maternal and fetal outcome statistics.