Trauma in Pregnancy
Authors: Howard A. Werman, MD, FACEP, Professor of Clinical Emergency Medicine, The Ohio State University, Medical Director, MedFlight of Ohio; and Robert E. Falcone, MD, FACS, Clinical Professor of Surgery, The Ohio State University.
Peer reviewer: Dennis Hanlon, MD, FAAEM, Vice Chairman of Emergency Medicine, Academics, Allegheny General Hospital, Pittsburgh, PA.
Trauma is the leading cause of death for women of child bearing age and for maternal death during pregnancy. Pregnancy increases a female's risk of physical and sexual abuse, resulting in significant morbidity and mortality for both the mother and the baby. Understanding the anatomic and physiologic changes that occur with pregnancy enhance the management of the pregnant trauma patient, potentially improving outcomes for both the mother and fetus. The best approach to fetal preservation is careful attention to resuscitation of the mother.
The Editor
Introduction
Pregnant females commonly sustain traumatic injuries. As with all other trauma victims, the priorities in patient assessment remain the same; however, anatomic and physiologic changes that occur as the result of the developing fetus will alter overall patient assessment. In addition, after 23 to 24 weeks of gestation there are actually two patients, the mother and the fetus. Under certain circumstances, independent decisions must be made regarding their care. As a general principle, excellent care for the mother also provides excellent care to the fetus. Most injuries require the multidisciplinary care often found in trauma centers. This issue reviews the pertinent information on the assessment and optimal management of trauma in pregnancy. An extensive bibliography has been included to allow the reader to pursue this subject in more depth.
Incidence and Demographics
Trauma is the leading cause of death for females of child-bearing age. It also is the leading cause of maternal death in pregnancy, accounting for 46% of all deaths; this is far more common than death from obstetrical causes or complications of medical illness.1-6
The leading causes of maternal trauma are motor vehicle accidents (55%), falls (22%), assaults (22%), and burns (7%). Physical violence and assault are most common in the first half of pregnancy, and falls become important in the second and third trimesters.7,8
Maternal trauma also is the leading cause of fetal demise. Fetal death typically is due to maternal hypotension, hypoxemia, placental abruption, uterine rupture, direct uterine trauma, disseminated intravascular coagulation, and maternal death.9-18
Fetal loss complicates up to 5% of minor trauma.19,20 Physical findings such as uterine contractions, vaginal bleeding, and abdominal tenderness have been found to be poor predictors of preterm delivery and fetal demise; even abnormal fetal monitoring does not accurately predict fetal loss.21,22 The absence of these findings, however, along with normal fetal monitoring, has been uniformly predictive of a good outcome.7
Mechanism of Injury
Blunt Trauma. Motor vehicle collisions account for the majority of maternal trauma.7,9,13,23 Specific injuries to the spleen, liver, and retroperitoneum are more common due to the increased vascularity of these structures.24 The uterus is well protected within the confines of the pelvis in the first 12 weeks of gestation. As the pregnancy progresses, there is greater risk to the uterus, placenta, vagina, and fetus. After 12 weeks, the bladder is displaced both anteriorly and superiorly, making it more prone to injury. Pelvic fractures are a particular challenge in pregnancy; resulting in up to a 35% fetal loss.4,25
Up to one-third of blunt injuries are related to falls during pregnancy.7,13 It is the second leading cause of significant trauma in the second and third trimesters. The increase in falls is at least partially attributable to a change in the center of gravity during pregnancy. Recognizing this increased risk as the pregnancy progresses, many authorities recommend high-risk activities be avoided in the last trimester. Dunning and colleagues reported that 27% of pregnant patients surveyed reported a fall during pregnancy.26 Overall, there is less than a 10% risk of poor maternal or fetal outcome. However, 23% of those patients who were hospitalized following a fall delivered during that admission.27
Physical Violence and Abuse. In the United States, more than 1 million women are victims of domestic violence; pregnancy is a factor that increases the likelihood of physical and sexual abuse. Ten to thirty percent of pregnant females are victims of physical violence, with a resultant fetal demise of 5%.14,28-30 Common sites of trauma are head, neck, breasts, and abdomen. Homicide remains the second leading cause of trauma deaths in pregnancy.31 Pregnant women who are abused have both short-term (fetal demise, abruption, pre-term labor, rupture of membranes, and vaginal bleeding) and long-term (low fetal birth weight, maternal infections, and maternal drug/alcohol abuse) complications.19,32,33 Risk factors for abuse include drug and alcohol problems in a partner as well as a change in employment or less than a high school education. As with other patients who are abused, pregnant women are typically abused by someone intimately known to them and may be reluctant to report their abuse for a variety of reasons. One significant clue is a woman who delays prenatal care until late in pregnancy.34,35 Other signs of potential physical abuse include repeated emergency department visits, depression, a history that is incompatible with injuries present, and the persistent presence of the patient's partner. Emergency physicians and trauma surgeons should be trained to ask appropriate screening questions of all females (including those who are pregnant) to detect abuse, especially if they appear to demonstrate any of the high-risk behaviors previously described.19,36 Table 1 provides a sample of appropriate screening questions.
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Penetrating Trauma. Penetrating trauma accounts for 10% of pregnant trauma victims and is the cause of 24% of maternal deaths.9 Gunshot wounds and stab wounds are the most common mechanisms of penetrating injury. Six percent of injuries in pregnancy are directly attributed to firearms.13 A significant number of gunshot wounds are self-inflicted.
As with blunt trauma, the uterus becomes more vulnerable to injury as the pregnancy progresses. After the middle of the second trimester, the uterus protects much of the maternal abdominal contents. In a significant percentage of penetrating injuries, the uterus is the only abdominal organ that sustains injury. Maternal outcome is generally good with penetrating injuries; however, there is a corresponding high percentage of fetal loss (generally 40-70%) as the uterus, amniotic fluid, placenta, and fetus absorb most of the energy from penetrating objects or missiles. Maternal mortality is actually less common in pregnancy when compared to similar injury in non-pregnant patients. Stab wounds result in maternal injury only with upper abdominal injuries. Maternal visceral injuries are, thus, less common during pregnancy, complicating only 19% of cases and carrying a maternal mortality rate of 3.9%.37
Stab wounds to the pregnant abdomen are managed in the usual manner, although there has been recent emphasis on non-operative management of the patient. The penetrating object should be stabilized in place until surgical exploration is conducted. Delivery of the fetus is indicated if there are signs of fetal distress or the uterus must be evacuated to localize and control the site of bleeding. More conservative methods of managing the fetus are indicated for fetal death in cases in which maternal injury has been excluded.
Physiology of Pregnancy
An understanding of the unique anatomic and physiologic changes in pregnancy is essential in caring for the pregnant patient who sustains injury. Virtually every organ system is impacted by the changing hormonal milieu and the growth of the uterus, placenta, and fetus as the pregnancy advances.
Major changes occur in the cardiovascular and pulmonary systems during pregnancy. Cardiac output increases up to 40% above baseline, much of which is diverted to support the developing fetus. Systemic and pulmonary vascular resistance falls during pregnancy to its nadir by the 28th week. The baseline blood pressure may drop by as much as 15-20%, resulting in a 5 to 15 mmHg decline in both systolic and diastolic blood pressure late in the second trimester. As full term approaches, these pressures begin to return to their normal values. There is significant remodeling of the cardiac chambers with a thickened left ventricle and some degree of valvular insufficiency. The heart rate increases during pregnancy; thus, it is not uncommon to have 10-15% increase in heart rate in the third trimester. A low blood pressure and elevated pulse in a pregnant patient can mistakenly be interpreted as normal physiology when in fact there is significant ongoing blood loss.
Blood volume increases by 30-50% during pregnancy; red blood cell mass increases by only 10-15%. This produces a normal physiologic anemia in pregnancy with a normal hematocrit measured between 32-34%. This is thought to protect the mother from blood loss during childbirth, which averages 500 mL for vaginal deliveries and 1000 mL for cesarean sections. When a pregnant trauma patient does exhibit signs of hypovolemic shock, she will have lost a greater percentage of blood (>30% or more) than the average non-pregnant patient. Maternal deterioration can proceed rapidly after the loss of 2500 mL of blood.
Other hematologic changes include a normal elevation of the white blood cell count to 12,000 cells/cm3. Serum clotting factors and plasma proteins increase during pregnancy, resulting in a hypercoagulable state. Fibrinogen levels, as well as the levels of factors VII, VIII, IX, and X, are all increased during pregnancy, with the rise in fibrinogen most notable. Normal serum fibrinogen levels in a pregnant patient with trauma may suggest early DIC (disseminated intravascular coagulation).
Oxygen consumption increases by 60% during pregnancy when compared to 8 and 12 months post-partum.38 There is an accompanying 50% increase in minute ventilation, along with a decrease in functional residual capacity by 20-25%. This is primarily caused by a 4 cm elevation of the diaphragm and a 5 to 7 cm widening of the lower chest wall caused by the gravid uterus. The increased minute ventilation leads to a "normal" paCO2 of 28-30 mmHg in pregnancy. The net result of these changes is that the pregnant female will have greater oxygen requirements along with a smaller reserve. As a result, rapid oxygen desaturation can occur, and these patients will abruptly desaturate during rapid sequence intubation. It should be noted that the fetus is protected from hyperoxia; supplemental oxygen poses no harm to the developing fetus. Thus, all pregnant trauma victims should receive oxygen supplementation. Additionally, the level of 2,3 diphosphoglycerate (DPG) is elevated in pregnancy, causing a shift in the oxygen dissociation curve and greater release of oxygen to fetal tissues. Maternal hypocapnea and acidosis also cause a shift in the oxygen dissociation curve, leading to reduced oxygen delivery due to greater affinity of hemoglobin for oxygen molecules. Additional findings in pregnancy include an increased arterial pH, decreased pCO2, decreased serum bicarbonate, and slightly increased paO2 with a measured arterial blood gas.
The heart rotates to the left from elevation of the diaphragm resulting in both T-wave inversion and Q waves in the inferior cardiac leads. Echocardiography demonstrates thickening of the left ventricle along with small pericardial effusions and mild pulmonic and tricuspid regurgitation.39
Renal blood flow increases by almost 50% in pregnancy. As a result, the normal BUN (blood urea nitrogen) and creatinine levels are lower in pregnant females. Conversely, a "normal" BUN and creatinine level in advanced pregnancy may indicate renal dysfunction. Gastrointestinal motility decreases during pregnancy due to effect of progesterone with increasing risk of both gastrointestinal reflux and aspiration of gastric contents. There is resistance to insulin during pregnancy, increasing the likelihood of precipitating a diabetogenic state.
Uterine blood flow has poor autoregulation and is almost linearly dependent upon maternal systolic blood pressure. Uterine blood flow increases from 60 mL/min to 600 mL/min (or 10% of cardiac output) as pregnancy progresses. Uterine injury thus can result in significant blood loss. As a result of early hypotension, the mother's physiologic response is that of self-preservation. The result is alpha-adrenergic stimulation, whereby uterine blood flow is sacrificed for maternal systemic blood flow. During periods of hypoxia and hypotension during trauma, fetal tachycardia, loss of variability, and fetal heart rate deceleration can be seen. The first signs of distress may not occur until hemorrhage of 1500 to 2000 mL. Additionally, maternal hyper- or hypocapnea can cause uterine vasoconstriction. This may lead to fetal hypoxia and acidosis. Even uterine contractions, which commonly occur after maternal injury, can compromise uterine blood flow.
In the supine position the gravid uterus, which averages 4500 gms at term, can compress the inferior vena cava. This decreases venous return, with resultant diminished cardiac output by as much as 30% in the supine position.40 In addition to causing hypotension, the increase in venous pressure also can increase vascular bleeding from pelvic or lower extremity fractures.
The physiologic changes in pregnancy are summarized in Table 2.
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Management of the Pregnant Patient
Prehospital Transport. The priorities in patient management remain the same in the prehospital environment. A uterine fundus that is palpated midway between the xiphoid and umbilicus suggests a viable fetus. Ideally, all pregnant trauma victims with a viable fetus should be transported to a trauma center where committed multidisciplinary services, including obstetrical resources, are available.41 Other indications for transport to a trauma center include tachycardia, chest or abdominal pain, loss of consciousness, and third-trimester gestation.42
Initial Management. The general approach to resuscitation of the pregnant female is to address the priorities outlined in the American College of Surgeons' Advanced Trauma Life Support course and attend to the obstetrical issues during the secondary survey when the mother has been stabilized. Some specific differences, however, are outlined below.
Airway with Spinal Protection. Due to the higher risk of aspiration and the greater likelihood of hypoxic decompensation in pregnant females, early intubation is recommended. All pregnant females should be considered a difficult intubation.43,44 Preoxygenation is extremely important due to the pregnant patient's tendency to desaturate rapidly during rapid sequence intubation, the preferred technique for intubation. When possible, the most experienced provider, following the ASA (American Society of Anesthesiologists') Guidelines for the difficult airway modified for trauma,45,46 should perform the intubation. Awake fiberoptic intubation may be considered. Supraglottic airway devices can be an effective alternative in ventilating the pregnant female.47 If the patient cannot be intubated or ventilated, preparations for surgical cricothyroidotomy should be made.
Neither depolarizing nor non-depolarizing paralytics cross the placental barrier. However, lower doses of succinylcholine should be selected due to the natural decline in pseudocholinesterase levels in pregnancy.48 Short-acting induction agents such as thiopental, propofol, and midazolam are safely used in pregnancy but have significant hemodynamic effects in trauma patients. Ketamine can be used in patients who are at risk for hypotension but should be avoided in those with intracranial injuries. Etomidate is a class C drug in pregnancy but is generally the preferred induction agent at many trauma centers, and is advocated in at least one review of the anesthetic literature on pregnancy in trauma.49
While observing standard spine precautions, patients beyond 20 weeks gestation should be transported in the left lateral tilt or decubitus position. Some late third trimester patients may not tolerate the supine position due to respiratory distress, and these patients will require reverse Trendelenburg positioning in addition to a left tilt.50 All patients should be on high flow oxygen as the fetus is less tolerant of hypoxia.
Breathing. Any chest wall or lung injury is poorly tolerated in the later stages of pregnancy due to altered respiratory function. Chest tube insertion, if required, should be conducted 1-2 interspaces above the normal landmarks for tube thoracostomy because of elevated diaphragms.
Both the uterus and fetus respond poorly to hypocapnea or hypercapnea and the resultant acid/base changes. Mild hypocapnea (pCO2 = 27 to 30 mmHg), which may be indicated for pregnant patients with evidence of acutely elevated intracranial pressure, is tolerated by the fetus. Positive pressure ventilation with PEEP (positive end-expiratory pressure) is not contraindicated by pregnancy.
Circulation. The goal of resuscitation is to restore maternal circulation and reduce the effects of maternal shock. The patient should be placed in the left lateral position to reduce aortocaval compression by tilting the backboard to the left 15 degrees or manually displacing the uterus if this was not already done by the pre-hospital personnel.
Tachycardia and hypotension should not simply be attributed to normal physiology and should be considered potential signs of blood loss. With the increased plasma volume, the pregnant patient may not display signs of shock until she has lost more than 30% of her blood volume. Fluid resuscitation with crystalloid and blood products should be aggressive to optimize uteroplacental perfusion.51
Lactated Ringer's solution may have some practical advantages over normal saline.52,53 Neither colloids nor hypertonic saline have been specifically studied in pregnant patients. Autotransfusion may risk amniotic fluid contamination and subsequent amniotic fluid embolism. However, at least one study suggests the risk is low when the cell-saver is used in conjunction with a leukocyte pore filter.54 Blood products (O-negative) should be administered as indicated when there is no response to crystalloids. In addition to fluid losses, other causes of hypotension should be considered, including neurogenic shock and amniotic fluid embolism.55
Disability. A baseline neurologic examination should be conducted, especially if intubation and the use of paralytics is considered. The goal is to perform a quick assessment for signs of intracranial hemorrhage and spinal cord injury. Management of patients with an expanding intracranial mass or other causes of increased intracranial pressure should proceed as it would in patients without pregnancy. Hypertonic agents such as mannitol and hypertonic saline should be used with caution in pregnant patients with traumatic brain injury due to the theoretical concern over the development of oligohydramnios in the uterus. Seizures in pregnancy should raise the additional concern of eclampsia.
Management of pregnant patients with spinal cord injuries includes the use of high-dose steroids as in other settings. Additionally, fluids and dopamine are safe for the initial management of neurogenic shock, although there is a theoretical concern about compromising uterine blood flow with higher doses of dopamine.
Exposure/Environment. A complete examination of the patient for signs of injury requires proper patient exposure. The patient should be carefully log-rolled to assess for injuries on the back. If the backboard is subsequently removed, the left side of the patient should be elevated with a pillow or towel roll. As with all other trauma victims, hypothermia is associated with an increased incidence of coagulopathy and worsening outcome; therefore, attention to the patient's thermal environment is essential.
Once the primary survey has been completed, a nasogastric tube and Foley catheter may be inserted. Because of nasal venous engorgement, the risk of epistaxis following nasogastric insertion should be anticipated. The risk of urinary tract infection also is greater in pregnant females, so urinary catheters should remain in place only as needed. Tetanus toxoid should be administered as indicated.
Laboratory and Radiologic Studies. Routine laboratory testing in the trauma victim depends on the institutional protocols and underlying patient condition. In many trauma centers, a type and screen, a hemoglobin, urinalysis, and urine pregnancy test (for females of child bearing age) may be all that are required. Further testing in the pregnant trauma victim should include a coagulation profile. An arterial blood gas and serum lactate may be considered due to the association between maternal acidosis and fetal demise. Rh negative patients should receive anti-D antibody (Rhogam 300 mcg) within the first 72 hours and additional doses of 300 mcg for every 30 mL of estimated exposure to fetal blood (based on Kleihauer-Betke results) to prevent isoimmunization.56,57
Standard x-rays should be obtained as needed. Where possible, a protective lead apron should be used to minimize fetal radiation exposure. Radiation doses of less than 5 rads are not associated with increased pregnancy loss or fetal abnormalities and no study has demonstrated increased teratogenicity below 10 rads. Teratogenesis, childhood cancer, leukemia, mental retardation, and microcephaly become a concern for radiation doses in excess of 12 to 20 rads.58-61 Common radiation doses for radiographic studies are presented in Table 3.
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The FAST (Focused Assessment with Sonography for Trauma) examination is an excellent screening tool to quickly assess for intra-abdominal fluid (blood), the possibility of pregnancy, and fetal viability if one is identified.62-65 The ultrasound is the safest imaging modality in pregnancy. However, ultrasonography typically provides limited information regarding the presence or absence of intraperitoneal fluid. A positive FAST examination in an unstable patient suggests the need for immediate laparotomy; in a stable patient, the abdominal CT scan should be obtained to determine the need for an operative intervention. In addition, the diagnostic peritoneal lavage (DPL) can be performed safely using an open supraumbilical approach for equivocal FAST examinations.66 However, this technique requires significantly more training than ultrasonography and poses greater risk to the pregnant patient.
Obstetrical Management
The obstetrical management of the patient begins once the trauma assessment moves into the secondary examination. Even in the case of relatively minor injuries, any patient with a viable pregnancy should be seen by an obstetrician, and a period of fetal monitoring, including ultrasonography and cardiotocography, should be provided.67
Part of the secondary examination should include assessment of the abdomen for tenderness, uterine tone, contractions, and tenderness. A pelvic examination should be performed using a sterile speculum to detect any pregnancy-related vaginal bleeding and the presence of amniotic fluid. Rectal and vaginal examination should be conducted even in the presence of pelvic fractures. Specific examination also may be conducted to determine cervical effacement, cervical dilatation, and fetal position.
Fetal monitoring of fetal heart rate and uterine activity should be initiated under appropriate conditions as early as possible in all pregnant females at more than 24 weeks of gestation. The fetus may demonstrate signs of distress while the maternal vital signs are adequate. This may signify under-resuscitation of the mother. Monitoring should be supervised under the direction of an obstetrician and appropriately-trained obstetrical staff.
In the absence of other significant injuries, most patients can be monitored for a period of 4-6 hours and then safely discharged if there are no signs of fetal distress, premature labor, or vaginal bleeding. Patients who are discharged under these conditions should be given clear instructions to return for any signs of preterm labor or placental abruption, including regular contractions, abdominal pain, or vaginal bleeding. However, any abnormalities noted in the first 4-6 hours require an extended period of observation for at least 24 hours; cardiotocographic monitoring also should be continued if the patient requires admission for other injuries.6,19
Emergency cesarean section may be indicated to control obstetrical bleeding from placental abruption or uterine rupture. Additionally, it may be required to provide better surgical exposure for non-obstetrical abdominal injuries. Finally, the procedure may be indicated for persistent fetal distress if the gestational age is 25 weeks or greater. Emergency cesarean section under these conditions is associated with a fetal survival rate of 45% and maternal survival of 72%.68
Special Considerations
Placental Abruption. Placental abruption is the most common obstetrical complication of blunt trauma and the second most common cause of fetal demise.40,69-71 Placental abruption occurs in 1-5% of minor trauma and 20-50% of major trauma. Mortality for the mother is less than 1%, but fetal mortality is 30-60%.71,72
Signs of abruption include uterine tenderness, tetany, vaginal bleeding, and contractions. Placental abruption does not always present with vaginal bleeding. Abdominal tenderness, however, is almost uniformly present. Abruption may be complicated by hypofibrinogenemia, DIC, and hemorrhagic shock. Ultrasound only identifies up to 50% of acute abruptions.61 Fetal distress is noted in 60% of cases and cardiotocographic monitoring is the most reliable method of detecting abruption.15,73,74 Cesarean section is performed for maternal complications and fetal compromise. Vaginal delivery may be performed for a stable viable fetus and in the absence of maternal complications.
Uterine Rupture. Uterine rupture is uncommon. There is a high association with pelvic fracture.4 It carries a maternal mortality of only 10% but results in nearly 100% fetal loss. The patient typically presents with a severe abdominal pain and associated guarding and rebound, and often complains of shoulder pain. Uterine asymmetry or fetal parts may be palpated on examination. Signs of shock are common. The diagnosis can be established by plain radiography, although ultrasound is more commonly employed. Fetal monitoring reveals fetal tachycardia, decreased beat-to-beat variation, and deceleration with bradycardia.21 The diagnosis is confirmed and managed by laparotomy.
Uterine Contractions and Premature Labor. Uterine contractions result from prostaglandins, which are released because of direct uterine trauma. Seventy percent of contractions following trauma resolve spontaneously. Premature labor with contractions and evidence of effacement and dilatation occurs in the remainder of patients. Preterm labor is treated with tocolytic agents and steroids to promote fetal lung development. Tocolytic therapy should be avoided in cases in which fetal distress or maternal complications mandate immediate delivery and the fetus is more than 36 weeks or less than 20 weeks.
Magnesium sulfate may be an appropriate tocolytic agent. However, magnesium sulfate is a smooth muscle relaxant and may exacerbate maternal hypotension. Nifedipine has recently been gaining popularity.75,76
Maternal Burn Injury. Minor burns rarely have significant consequences for the fetus. For major burns, fetal outcome directly parallels maternal outcome. Early fetal loss occurs as the result of fluid loss and maternal hypoperfusion in the first 12 hours. Aggressive fluid resuscitation is as applicable to the pregnant female as any other burn victim. The rule of nines is modified by adding 5% for burns over the gravid uterus.
The other major complication of burns in pregnancy is preterm labor. Emergent delivery for gestational age > 25 weeks may be indicated for patients with major burns and significant complications.77 Tocolytic therapy may be considered if the burn injury is less than 30 percent body surface area and the gestational age is between 24 and 32 weeks.
Inhalation injuries may produce maternal hypoxia, which has profound consequences for the fetus. Early intubation should be considered. In addition, fetal hemoglobin has a greater affinity for carbon monoxide than adult red blood cells. Aggressive management with 100% supplemental oxygen is warranted. In addition, some sources recommend that all pregnant females undergo hyperbaric oxygen treatment if there is any exposure to carbon monoxide.78
Electrical injuries also may pose a risk to mother and fetus. Low voltage injuries do not appear to pose any risk to the developing fetus, although the literature presents conflicting data.79-81 The role of fetal monitoring in low-voltage exposures is unclear. High-voltage electrical injuries, particularly when the current path goes from the hand to the feet, increases the risk of fetal death and complications such as growth retardation, placental abruption, and spontaneous abortion. Lightning injuries in pregnancy are rare.82
Perimortem Cesarean Section
Post-mortem cesarean sections were commonly performed throughout the 19th century when maternal mortality was between 2-5%; infant survival was rare. Ritter83 reviewed the literature and reported on 120 perimortem cesarean sections in which the infant survived. Katz recommended that perimortem cesarean section should only be considered for mothers at greater than 24 weeks gestation with loss of vital signs for no more than 4 minutes. For maximum survival, delivery of the infant was to be accomplished within 5 minutes. This initial recommendation was made for all cases of cardiopulmonary arrest (including trauma) in the mother.84 However, a review of this work revealed that at least one normal infant survived more than 21 minutes of maternal CPR. In a subsequent review, Katz and colleagues85 found 38 patients who underwent emergency cesarean section within the appropriate time frame. Thirty-four infants were long-term survivors and 13 mothers survived. However, of eight cases performed for traumatic arrest, only three infants and no mothers survived. This was primarily due to the long interval between time of arrest and cesarean section.
Perimortem cesarean section is performed using a generous vertical incision from the xiphoid to the pubic and a vertical upper uterine segment incision once the uterus is exposed. This procedure should immediately be considered in any viable fetus in which cardiopulmonary arrest occurs in the setting of trauma. Fetal salvage is best if the infant is delivered within 10 minutes and ideally in the first 4-5 minutes of maternal arrest; however, survival has been reported with episodes of prolonged maternal arrest.83-86 The surgery not only serves to preserve fetal viability but also evacuates the uterus and reduces aortocaval compression,87-89 and maternal cardiac output will increase by 60-80% of pre-pregnancy levels.86 The FAST exam can be used to confirm the absence of maternal cardiac activity and the presence of fetal viability.90
Treatment of cardiac arrest in pregnancy is otherwise not altered. However, chest compressions may be less effective. Open thoracotomy should be considered for the viable fetus as well performed open chest compressions may improve fetal survival. It is important to note that, if performed after an emergent thoracotomy, aortic cross-clamping may worsen placental and fetal perfusion.
Injury Prevention
Not surprisingly, the single most important intervention in preventing maternal and fetal injury is the use of restraint systems in motor vehicle operation. Proper use of seatbelts has been shown to be the best predictor of maternal and fetal outcome in motor vehicle crashes.91 Unfortunately, only 46-66% of pregnant trauma patients have been found to use restraints during motor vehicle operation.9,14,92 Additionally, a survey-based study of 450 pregnant women who used seatbelts reported a 73% rate of correct use of seatbelts during pregnancy. The most common reason for lack of restraint use was patient discomfort (53%), followed by forgetfulness (37%). Ten percent believed that seatbelts would harm the fetus during a motor vehicle crash.93 This and other studies support the fact that only about one-third of pregnant patients report receiving information about proper restraint system use.93-95 On the other hand, Pearlman and Phillips96 demonstrated that most of those who were educated wore their seatbelts (83%) and could identify proper placement (77%).
Correct placement should include a shoulder strap between the breasts and the lap belt positioned across the hips. Placement of the lap belt over the dome of the uterus places the fetus and uterus at risk of injury97 and premature delivery within 48 hours of injury.98 Airbags also contribute to safety in the passenger compartment.99 Although studies are conflicting,69,100 Sims and coworkers99 have shown that there is no increased risk of placental abruption, preterm labor, fetal injury, or complicated deliveries with airbag deployment. Improper placement of the seatbelt increases the incidence of maternal hemorrhage from uterine rupture and a three-fold incidence of fetal death.101,102 One recent study103 determined that almost half of fetal losses could be prevented by appropriate seatbelt use among pregnant patients involved in motor vehicle crashes. These data suggest seatbelt education is vital to appropriate prenatal care.
Summary
Care of the pregnant trauma victim often requires a multi-disciplinary approach found in a trauma center. The priorities in caring for the pregnant trauma victim remain unchanged. However, the unique anatomic and physiologic changes associated with pregnancy must be understood. The best approach to fetal preservation is careful attention to resuscitation of the mother. When these attempts fail, emergent perimortem cesarean section should be considered early. Preventive measures such as proper restraint system use and screening for evidence of domestic violence offer the best approaches to improving maternal and fetal outcomes in trauma.
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Understanding the anatomic and physiologic changes that occur with pregnancy enhance the management of the pregnant trauma patient, potentially improving outcomes for both the mother and fetus. The best approach to fetal preservation is careful attention to resuscitation of the mother.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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