Chapter 18: Trauma and Pregnancy

Trauma is a major cause of maternal and fetal morbidity and mortality. The incidence of trauma during pregnancy has been estimated to be 3% to 8%. In 2002, there were 16,982 injury hospitalizations of pregnant women in the United States, which corresponds to 4.1 per 1000 deliveries.¹ However, many more women seeking care for injuries do not require inpatient care. A study of 295 women with injuries during 2001 to 2005 showed that 52% were discharged from the emergency department (ED), and only 18% were admitted to the trauma service.² In one study, 1 in 7 pregnant women sought care for injury in Massachusetts during 2002 to 2003. For some subgroups, the rate was as high as 1 in 4.³ Analysis using American College of Surgeons National Trauma Data Bank (NTDB) confirmed that pregnant patients tend to be younger, less severely injured, and more often black or Hispanic when compared to nonpregnant controls. Twenty per cent of pregnant patients tested positive for drugs or alcohol, and 1 in 3 involved in motor vehicle crashes (MVCs) did not use seat belts.⁴ Other studies agree that trauma is more common among adolescents, black women, those with public insurance, less than high school education, substance abuse, or lack of safety restraints.^3,5

Types of Injury

The most common types of trauma during pregnancy include MVCs (48%), falls (25%), and assaults (17%). Intentional injuries (homicide/suicide), gunshot wounds, burns, and poisonings each account for fewer than 5% of cases.⁶ Regarding abdominal injuries, one large center reported that 91% were blunt injuries, while 9% had penetrating trauma.⁷

Motor Vehicle Crashes

Motor vehicle crashes (MVC) comprise at least two-thirds of traumas during pregnancy, a fact that is not surprising, since the average number of miles driven annually by women of reproductive age increased from 3721 to 8258 between 1975 and 2001.⁸ A study of 427 pregnant women in MVCs showed that maternal age was similar to that for nonpregnant women; cases were distributed evenly across trimesters. Seventy percent of pregnant women in crashes were drivers, 14% of which were unrestrained, rates similar to nonpregnant women. Mean injury severity was generally lower for pregnancy, but pregnant women were more likely to be transported.⁹ Women hospitalized after MVCs are known to be at risk for adverse pregnancy outcomes, but recent data suggest the risk is increased even after minor collision during pregnancy.¹⁰

Injury Due to Fall

Posture is stable in the first trimester, but destabilizes in subsequent trimester and for at least 6 to 8 weeks postpartum. In one study of static postural balance, 25% of pregnant women reported falling within the preceding 3 months, whereas no control subjects had fallen in the preceding year.¹¹ Biomechanical studies confirm that postural sway increases, stance is wider, and perception of balance is decreased in late gestation.¹² Hospitalizations due to falls are 2.3 times more likely in pregnancy. One report compared 693 pregnant women hospitalized with fall injuries against 2079 pregnant controls. Hospitalization due to fall was seen in 49/100,000 deliveries; 79% occurred in the third trimester, with 11% and 9% in the second and first trimesters, respectively. Fracture was the most common injury (47%), usually involving lower extremities, while 18% had contusions and 17% had sprains. Most injuries were minor. Nonetheless, pregnant women who fell had a 4-fold higher risk for preterm labor (PTL) and an 8-fold higher risk for abruption.¹³

Assault/Intimate Partner Violence

Contrary to popular assumptions, intimate partner violence (IPV) during pregnancy is not rare and is seen in all socioeconomic strata. Assaults during pregnancy typically involve areas of the body covered by a “1-piece bathing suit.” Estimates vary, but up to 15% to 25% of women receiving prenatal care in public health clinics report IPV. Adolescents appear to be at particular risk, both before and during pregnancy. Whites have higher rates of IPV than blacks or Latinas, but black women are the most likely to be murdered. Alcohol and substance abuse play a significant role in IPV for both perpetrators and victims. Overall, pregnant victims of IPV are more likely to receive no prenatal care or delay entry into prenatal care. In fact, IPV is cited as a common reason women choose to terminate a pregnancy.¹⁴ IPV during pregnancy is linked with a variety of adverse outcomes. Data from the pregnancy risk assessment monitoring system (PRAMS) survey of 118,579 women in 26 states showed that those reporting IPV in the year prior to pregnancy had higher risks for high BP or edema, vaginal bleeding, severe nausea and vomiting, kidney infection or UTI, hospital visits, preterm births (PTB), low birth weight (LBW), and need for neonatal intensive care unit (NICU) care.¹⁵ Another cohort study reported on women who experienced violence before or during pregnancy versus women with no prior violence. Overall rates of PTB were similar, but married women who experienced violence had a higher proportion of LBW and preterm infants.¹⁶ Obstetric risks related to IPV were also found in a study of 105 women who reported IPV during prenatal care. After controlling for sociodemographics, tobacco, alcohol, drugs, preeclampsia, and diabetes, there remained a 32-fold greater risk for trauma and a 5-fold greater risk for placental abruption.¹⁷ The most extreme result of IPV is homicide. A case control study in 10 cities compared 437 gravidas who experienced attempted and/or completed homicide with similarly abused nonpregnant women. Abuse during pregnancy was reported by 23% to 26% attempted and/or completed homicide victims, versus 8% of controls. Five per cent of homicide victims were murdered while pregnant. The risk of being a homicide victim was 3 times higher for women abused during pregnancy.¹⁸ A study of homicide during pregnancy explored data from the New York Office of the Chief Medical Examiner. The victim and suspect were known to each other in 18 of 27 cases. Of these, 16 were involved in an existing or prior intimate relationship, confirming the strong role of IPV in maternal homicide.¹⁹ Universal screening for domestic violence is recommended by professional organizations, such as the American Medical Association (AMA), American College of Obstetricians and Gynecologists (ACOG) and the American Academy of Family Physicians (AAFP). Should a patient indicate that IPV is a concern, assistance is available from the National Domestic Violence Hotline (1-800-799-SAFE). A variety of other local resources may be available in many communities.

National Domestic Violence Toll Free Hotline 1-800-799-7233

• ACOG Violence Against Women Resources: www.acog.org/About_ACOG/ACOG_Departments/Violence_Against_Women

• National Coalition Against Domestic Violence: http://www.ncadv.org

Mechanisms of Injury

Blunt Abdominal Trauma

Blunt abdominal trauma accounts for most cases of maternal trauma, most of which are related to MVCs. Falls, pedestrian injuries and assaults are other common etiologies. The risk for maternal or fetal complications relates to the gestational age at delivery. The uterus is protected within the pelvis until roughly 12 weeks. At 20 weeks, the uterus is at the level of the umbilicus. After 20 weeks, the fundal height (in centimeters) corresponds to weeks of gestation. The bladder is displaced upward as the uterus grows, making it an intra-abdominal organ vulnerable to injury. The uterine wall becomes thinner and the relative amount of amniotic fluid decreases with advancing gestation; these changes contribute to the possibility of adverse placental or fetal effects. Potential sequelae of blunt trauma relate to characteristics of the force and size of the uterus, and include placental abruption, uterine rupture or even direct fetal injury.²⁰

Penetrating Abdominal Trauma

About 9% of maternal abdominal injuries are due to penetrating trauma, with prevalent injuries being gunshot (73%), stabbing (23%) or shotgun (4%). Maternal and fetal risks are related principally to severity of abdominal injury and maternal hypotension. Although maternal risk of mortality (3%-4%) is lower than for nonpregnant women, the risk of fetal injury and death is as high as 73%.^7,21 This makes sense, given that the gravid uterus in late pregnancy would absorb much of the energy from projectiles, would displace bowel peripherally, and would prevent vascular injury by occupying the space anterior to the great vessels.

The overall approach for management is similar to that of nonpregnant patients, with penetrating objects left in place until imaging and/or surgical exploration can be affected. In nearly all cases, abdominal exploration is required. However, a selective approach to laparotomy was described in a series of 14 gravidas with penetrating trauma. The authors found that visceral organ injury was more likely if the entry wound was in the upper abdomen, but not when below the uterine fundus. For cases of lower abdominal injuries, observation and wound exploration were considered so long as the fetal status was satisfactory.²² Generally, superficial stab wounds may be observed if confined to the abdominal wall, but laparotomy is required if intraperitoneal bleeding or bowel injury is suspected. Cesarean delivery may be indicated if a viable fetus is in imminent risk of death or if the gravid uterus prohibits exposure to repair maternal injuries.²³

Maternal Injury and Death

Fractures, dislocations, sprains, and strains were the most common injures affecting pregnant women in one large study. Women whose injuries resulted in delivery during their trauma hospitalization had extremely high odds of maternal death (odds ratio [OR] 69), fetal death (OR 4.7), uterine rupture (OR 43), and placental abruption (OR 9).⁶

Trauma is the leading cause of nonobstetric maternal deaths. A report of 95 maternal deaths in Chicago found that 46% were due to trauma. Of these, 57% were due to homicide, 9% suicide, 23% gunshot wound, 21% MVCs, 14% stabbing, 14% strangulation, 9% blunt head injury, 7% burns, 5% falls, 5% toxins, and 2% drowning.²⁴ Similarly, New York medical examiner records concluded 39% of deaths in pregnant women were injury-related, with homicide in 63%, suicide in 13%, and 12% due to MVCs.²⁵ Pregnant women actually exhibit lower mortality rates than nonpregnant controls when they are matched for age and equivalent injuries.²⁶

Homicide is an important cause of death among pregnant and postpartum women. Data from the Pregnancy Mortality Surveillance System (1991-1999) were used to review 617 homicides, which corresponded to 1.7/100,000 live births. These represented 8% of all maternal deaths, and 31% of pregnancy-associated injury deaths. Homicide was the second leading cause of maternal injury deaths after MVCs. Risk factors for maternal homicide included age less than 20 years and late/no prenatal care. Firearms were the leading mechanism in more than half of cases. Homicide was 7 times higher for black versus white women.²⁷ A statewide study in North Carolina found similar results, with homicide accounting for 36% of injury-related maternal deaths and nonwhites being at 1.8 times higher risk.²⁸

Suicide is less common than homicide, accounting for 10% of maternal deaths. A history of prior suicide attempt increases the risk sharply and a family history doubles the risk. Other risk markers include adolescence, unmarried status, financial strain, and intimate partner violence. Most suicides occur during the first trimester, with intentional overdose the most common method. Women who commit suicide after birth often make their attempt within the first 2 months and use more violent methods.²⁹

Miscarriage and Fetal Death

Estimates of fetal death rates after maternal trauma vary. A population-based study in Sweden evaluated traffic, medical, and autopsy registries, and found that MVCs during pregnancy were associated with a perinatal mortality rate of 3.7/100,000.³⁰ Danish women who received medical treatment for an injury at any time during pregnancy were also more likely to have a spontaneous abortion or stillbirth.³¹ Similar findings were seen in one U.S. study of fetal death certificates from 16 states over a 3-year period. Authors identified 240 fetal deaths due to maternal trauma, or 3.7 per 100,000 live births. MVCs accounted for 82% of cases, with firearms and falls accounting for 6% and 3% of cases, respectively. The highest rate of fetal deaths (9.3 per 100,000) was seen among teens aged 15 to 19 years. Placental injury was cited in 42% of cases, and maternal death also occurred in 11% of cases.³² Other reported risk factors for fetal death include prolonged maternal hypotension or hypoxemia, abruption, uterine rupture, and direct uterine trauma. It has been estimated by one author that the rate of fetal deaths due to MVC exceeds that of infant deaths by 7-fold.⁸

Specific clinical factors have been shown to be predictors of fetal death after blunt abdominal trauma, including ejection from vehicle, motorcycle or pedestrian collision, maternal death, maternal tachycardia, abnormal fetal heart rate (FHR), lack of restraints, and injury severity score (ISS) greater than 9.³³ Timing and severity of maternal injuries may affect the risk for miscarriage or fetal demise as is evident from the review of 376 fetal deaths reported in 2005. As anticipated, severe injuries were associated with a 6-fold increase in odds of fetal demise and prematurity/LBW. The odds of fetal demise after minor injury in the first trimester were increased by a factor of 1.8, and by 1.65 following a second trimester incident.³⁴

Structural Fetal Malformations

Recent data suggest that maternal trauma in early pregnancy increases the risk for structural fetal malformations. The National Birth Defects Prevention Study assessed periconceptional injuries and subsequent of birth defects. Associations were identified between longitudinal limb deficiency, gastroschisis and hypoplastic left heart syndrome (HLHS), and intentional injury. Other congenital heart malformations were increased, including interrupted aortic arch, ASD, pulmonary atresia, and tricuspid atresia, as was anorectal atresia or stenosis. This is cause for concern, and further research is warranted.³⁵

Preterm Birth and Low Birth Weight

Preterm labor (PTL) is common among trauma patients beyond 20 weeks (especially after blunt trauma), but episodes resolve spontaneously in many cases. Risk factors most predictive of PTL after blunt abdominal trauma include gestational age more than 35 weeks, assaults, and pedestrian collisions, according to one study.³³ However, recent literature suggests PTL may ensue after the initial injury. In one study, a 2-fold increase in PTB and LBW was found after discharge from injury hospitalization. The risk of PTL was higher with increasing injury severity and for injuries prior to 24 weeks.³⁶ Similar findings were reported in a study of 11,817 preterm/low birth weight (LBW) deliveries in Tennessee. After adjusting for race, advanced maternal age, smoking, and prior PTB, the authors found a doubling of odds for PTB/LBW in women with severe second- or third-trimester maternal injury. Surprisingly, women with mild injury in the first or second trimester were also 1.2 times more likely to have PTB/LBW than uninjured controls.³⁴ Finally, a study of 582 women from Washington State (1989-2001) evaluated outcomes after severe, mild, or no injury. Over 80% were discharged after their initial injury hospital stay. Those with severe and nonsevere injuries were at increased risk for abruption, cesarean, and fetal death. Surprisingly, uninjured women were also at risk for PTL (relative risk [RR] 7.9) and abruption (RR 6.6) compared with women not involved in collisions.¹⁰ Thus, it is important to observe for signs of PTL even beyond the initial trauma.

The use of tocolytic medications for PTL in injured women is controversial. One study evaluated 84 patients after major trauma in late pregnancy. Preterm contractions occurred in 28%, and 17 received tocolytic therapy. Five patients responded to 1 dose of terbutaline, while 8 received IV magnesium and 4 were given Ritodrine. Overall, 14 of 17 delivered at term.³⁷ In another study, 205 trauma patients were evaluated, of whom 18 had OB complications. Ten developed PTL and received tocolytic medications. All 10 responded initially, but 3 delivered in less than 12 hours due to abruption, and all others delivered prematurely 2 to 7 weeks later.³⁸ Finally, 85 women with blunt abdominal trauma were followed prospectively; 13 delivered preterm. Thirty-one percent who delivered preterm received magnesium, compared to only 7% with term births. There were no differences between groups in terms of clinical factors, but 46% with preterm birth (PTB) had complications such as premature labor and/or rupture of membranes (PROM) or abruption, versus 13% delivering at term.³⁹ ACOG Practice Bulletin Number 127 (2012) discusses current management of PTL: “Women with preterm contractions without cervical change, especially those with a cervical dilation of less than 2 cm, generally should not be treated with tocolytics.” Without specifically addressing PTL after trauma, the document states: “Because of the possible risks associated with tocolytic and steroid therapies, the use of these drugs should be limited to women with PTL at high risk of spontaneous PTB. Tocolysis is contraindicated when the maternal and fetal risks of prolonging pregnancy or the risks associated with these drugs are greater than the risks associated with PTB.”⁴⁰

Placental Abruption

Placental abruption complicates 1% of deliveries in the general population. Between 1979 and 2001, there has been an overall rise of 92% among black women and 15% in whites, either a true increase or a result of improved diagnosis.^41,42 Placental abruption is one of the most serious complications of blunt abdominal trauma, and has been estimated to occur in 7% to 9% after trauma with no or minor injury, but 13% after severe injury.¹⁰ The incidence may be even higher for women with severe abdominal trauma. Complications due to abruption depend on the severity of placental bleeding and gestational age. Classic signs and symptoms of abruption include vaginal bleeding, painful contractions, and a nonreassuring FHR pattern with late decelerations. However, the clinical presentation can be subtle, especially in cases of concealed hemorrhage. Trauma-related abruption could be due to shear failure (differences in the elasticity of myometrium and placenta) or tensile failure (coup-contrecoup injury). Risk markers for abruption reported in various clinical studies include low maternal education, nonwhite race, lack of seat belt use, and high-speed collision.²⁰

Women hospitalized after MVC have been shown to be at higher risk for abruption, even when no maternal injury is present. The risk for abruption was 7 times higher for women evaluated due to MVC when compared to those not involved in collisions.¹⁰ Although late placental abruptions have been reported in 1% to 2% of patients up to 48 hours after blunt abdominal trauma,⁴³ abruption is usually diagnosed within 2 to 6 hours after trauma. A study of 85 women monitored by electronic fetal monitoring (EFM) for 4 hours after trauma showed there were no episodes of abruption within 24 hours when there were no contractions in any 10-minute interval and there were no symptoms of pain or bleeding.⁴³ Although the optimum duration of observation is unclear, most advise 2 to 6 hours of cardiotocography after trauma for women with pregnancies at or beyond viability.^43,44

Fetomaternal Hemorrhage

Fetomaternal hemorrhage (FMH) occurs when fetal blood enters the maternal circulation. The incidence of FMH is 3 per 1000 births (assuming 30 mL of fetal blood lost). However, the amount of fetal bleeding causing clinically significant fetal risk depends on the loss relative to total fetal blood volume and whether fetal blood loss is acute or chronic. Unfortunately, there are few early clinical signs of fetal anemia due to FMH. Classic signs of fetal anemia include abnormal FHR pattern (sinusoidal or otherwise nonreassuring), fetal hydrops, fetal atrial fibrillation, decreased fetal movements, or stillbirth.⁴⁵

The diagnosis of FMH can be challenging, since available tests have limitations. The current standard test is the acid elution test, or the Kleihauer-Betke (KB) test. KB testing involves determining the percentage of RBCs from maternal blood which stain positive for fetal hemoglobin (HbF). This test is labor intensive, and can underestimate fetal RBCs in late gestation (decreasing HbF content) or may overestimate in those who overproduce HbF (eg, thalassemia, sickle cell). Flow cytometry is more sensitive and accurate in measuring HbF, but is not available at all hospitals. Flow cytometry is indicated when results from KB testing or standard anti-D are discrepant or if there is maternal/fetal RhD compatibility.⁴⁶

FMH was correlated with PTL in a study of 71 pregnant trauma patients undergoing KB testing. Overall, 46 of 71 had positive KB results; Forty-four patients with PTL had positive KB tests. PTL was 20 times more common when KB (+) and no other PTL risk factors were identified. In 25 KB (-) patients, none had preterm contractions. The authors recommended KB testing for all trauma patients.⁴⁷ However, other studies question whether KB testing is useful in the setting of trauma. One hundred low-risk women underwent KB testing at the time of Glucola screening. KB results were compared to 583 patients with trauma evaluation at comparable gestational ages. Five per cent of “low-risk” women had positive KB tests, whereas 2.6% of trauma patients had positive KB tests. These results suggest that a positive KB may not always reflect a pathological FMH in patients with trauma.⁴⁸

The long-term prognosis is guarded for cases of massive FMH, but follow-up data are limited. Among 48 patients with massive FMH (KB ≥40/10,000 or FMH ≥20mL/kg), there were 6 fetal deaths. PTB and NICU transfer were seen in 19%, and neonatal transfusion in 10%. However, 31 of the infants followed over 8 years displayed no neurological sequelae.⁴⁹ Similar results have been seen in other series, but cases of cerebral palsy have been reported. Most authors continue to advise KB testing in cases of blunt abdominal trauma during pregnancy. If positive, fetal middle cerebral artery (MCA) Doppler velocimetry is indicated. If severe anemia is confirmed on MCA Doppler, intrauterine fetal transfusion, additional RHIG or delivery may be warranted.⁴⁵

Uterine Rupture

Uterine rupture is estimated to occur in 0.7% of all maternal traumas, which represents a 45-fold increase compared with nontrauma controls.⁶ Uterine rupture is thought to involve direct abdominal impact with high force. Most cases appear to involve the fundal region of the uterus, and the fetal prognosis is poor. Case reports suggest that maternal death may be more common than for cases of uterine rupture due to other causes. The extent of injury and clinical presentation are highly variable, but clinical features could include abdominal pain or distension, nonreassuring FHR pattern, and other signs of hypovolemia. Since hemorrhage can be life threatening due to the high uterine blood flow during gestation, laparotomy is always indicated, and hysterectomy may be required if the uterus cannot be repaired satisfactorily.^20,23

Direct Fetal Injury

Direct fetal trauma complicates fewer than 1% of all pregnancies following trauma. Most cases result from serious maternal injury or from penetrating trauma.^20,23 Unusual fetal consequences of trauma include limb-body wall complex, fetal subdural hemorrhage, and fetal CNS damage such as hydrocephalus or cerebral palsy. Numerous case reports describe direct fetal injury and/or long-term sequelae relating to trauma during pregnancy after MVCs, auto versus pedestrian collisions, motorcycle crashes, with or without seat belt use or airbag deployment, with penetrating trauma, and other scenarios.

Orthopedic Injury

As one might expect, the rate of maternal death and pregnancy complications is high in this setting. One study compared 65 women with orthopedic injuries to 990 controls at a Level I trauma center. Increased risks for delivery before 37 weeks (31% vs 3%), abruption (8% vs 1%) and perinatal mortality (8% vs 1%) were seen in the group with orthopedic injuries.⁵⁰ Another study of 3292 women with 1 or more fractures confirmed a sharp increase in maternal mortality (OR 169), as well as abruption and transfusion for those who delivered due to their injury. Women who were discharged undelivered had high rates of delayed complications, with a 46% increase in LBW and a 9-fold increase in thromboembolism. Pelvic fractures had the worst outcomes.⁵¹

Pelvic fractures confer a particularly high maternal and fetal risk. Pelvic and acetabular fractures during 101 pregnancies were associated with maternal mortality in 9% and fetal mortality in 35%, in one study. Maternal mortality was highest after automobile versus pedestrian collision. Mechanism of injury was important, since vehicular collisions were more strongly associated with fetal loss than falls. Injury severity was important, but fracture classification and type, and trimester did not affect outcomes in that series.⁵² Among 1345 women studied with pelvic and acetabular fractures in Israel, 1% were pregnant. Eleven of the pregnant women were treated conservatively, while 4 required surgery. Twelve of 16 fetuses survived, but 4 had nonviable pregnancies; one maternal death was reported. A team approach was suggested to determine the timing of orthopedic surgery and delivery, ensure judicious use of imaging with ionizing radiation and choice of orthopedic procedure.⁵³

There are limited data regarding the route of delivery following pelvic fracture. This issue was studied in 31 women with prior pelvic fracture. Among 25 vaginal births in 16 women after healed pelvic ring fractures, 28% had prior surgical treatment for pelvic fracture, and 16% had retained anterior or posterior hardware, including trans-symphyseal plating in 3 patients (12%). In contrast, 13 of the women had 26 cesarean deliveries, with 46% after surgical treatment for their pelvic injury. Although 2 women had elective repeat cesarean, 7 women underwent 12 cesareans resulting from their pelvic fracture. Three women elected cesareans despite their physicians offering trials of labor. Cesarean was not related to age, fracture pattern, treatment type, or residual pelvic displacement. At this time, there are no specific guidelines or indications for trial of labor after pelvic fracture.⁵⁴

Burn Injuries

About 7% of women of reproductive age are seen for treatment of major burns, but the exact incidence of burn injury during pregnancy is unknown.⁵⁵ Most case series come from outside the United States, so there may be significant difference in patient characteristics and treatments. A study of 51 patients from Iran showed that when burned surface area exceeded 40%, maternal and fetal mortality reached nearly 100%. Kerosene ignition was the most common reason for burns, and large burn area and inhalation injury were the most important factors contributing to death.⁵⁶

Complications from burns include acute respiratory distress syndrome (ARDS), sepsis, organ failure, or death. Types of burn injuries include thermal, electrical, chemical, and radiation. Thermal wounds contain 3 zones (coagulation, stasis, hyperemia), each with different clinical features. Electrical burns create severe entry/exit wounds, as well as severe injury to deep tissues. Subsequent myonecrosis can lead to liver or kidney dysfunction. Minor burns involve less than 10% of total body surface area (BSA) and are partial thickness injuries. Moderate burns comprise 10% to 19% of BSA, while severe burns involve 20% to 39% and critical burns affect greater than 40% of total BSA. Major burns also include electrical burns, persons with chronic illness or burns of the face or perineum. Early deaths after burns are usually due to respiratory complications. A frequent cause of mortality is inhaled carbon monoxide or cyanide.⁵⁷

All major burns require aggressive fluid resuscitation with salt-containing solution within the first 24 hours. Prophylaxis for stress ulcers and thromboembolism should be provided. Infection and sepsis are the greatest risks to life after the first 36 hours, either due to pneumonia or wound infection. Staphylococci are the most common pathogens initially, but after 5 days, gram negative rods such as Pseudomonas predominate. Wound care, debridement, and infection control practices are proven strategies for optimizing outcome. Early enteral feeding aids many aspects of recovery after burns, with a high caloric intake of 36 kcal/kg/d and protein intake of 1.5 to 2 g/kg/d. Skin substitutes or topical negative pressure (TNP) therapy may stimulate healing. Rehabilitation care is important to restore function and cosmetic appearance. Pain management may include the use of opioids, nonsteroidal anti-inflammatory drugs (NSAIDs), anesthetics or anxiolytics. Other treatment modalities could include hypnosis, cognitive behavioral therapy (CBT), and visualization.⁵⁷

General principles of burn management for pregnant women include aggressive fluid resuscitation, supplemental oxygen, low threshold for intubation, and high suspicion for deep vein thrombosis/pulmonary embolism (DVT/PE) or sepsis.⁴⁹ There are no formal guidelines regarding care of a pregnant woman with burn injuries, but a multidisciplinary approach seems important.⁵⁵ An excellent review is provided by Kennedy et al. In general, hemodynamic instability confers a higher risk for stillbirth. PTL has been associated with maternal acidosis or prostaglandin release after burn injury. Tocolysis should be used with caution in burn patients, since side effects may complicate management. Decisions regarding fetal monitoring or early delivery for maternal or fetal indications should be made on a case-by-case basis.⁵⁷

Physiological changes of pregnancy directly affect how pregnant women respond to trauma and how providers should interpret examination findings and laboratory values. Table 18-1 provides a summary of pertinent changes.

Prehospital Care

The National Center for Injury Prevention and Control guidelines for field triage recommends a 4-level approach to determine the need for care at a high-level trauma center. Level 1 consists of measuring vital signs and consciousness level. If initial assessment reveals an abnormal Glasgow coma scale (<13), SBP less than 90 mm Hg, respirations greater than 29 or less than 10/min or if ventilation is needed, transport to a level I trauma center is indicated. Level 2 involves assessing the anatomy of injury. Penetrating injuries, chest wall instability, more than or equal to 2 proximal long bone fractures, crushed or pulseless extremity, amputation proximal to wrist or ankle, pelvic fracture, open/depressed skull fracture or paralysis, all require high-level trauma care. Level 3 involves determining the mechanism of injury and evidence of high-energy impact. Patients with fall greater than 20 feet (2 stories), auto versus pedestrian collision, motorcycle crash, or high-risk auto crash (intrusion into car frame, ejection from vehicle, death within same compartment, or vehicle telemetry data consistent with high risk of injury) are candidates for transport to a level 1 trauma facility. Finally, level 4 takes into account special or system considerations. Examples include older adults, children, burns, bleeding disorders, and others. Pregnancies beyond 20 weeks belong in this category. Ultimately, the EMS provider can advise transport to a high-level trauma center if he or she judges it to be appropriate.⁵⁸

Pregnant women should be transported in the usual manner, taking care to position them with a 15-degree left lateral tilt, thus reducing aortocaval compression from the gravid uterus. If spinal injury is suspected, the rigid board can be tilted, or the uterus can be manually displaced leftward. Military antishock trousers (MAST) or a pneumatic antishock garment (PASG) have been used to support BP while transporting hypotensive patients with intra-abdominal trauma. However, their use is relatively contraindicated during pregnancy.²⁰ High-flow oxygen should be administered via non-rebreather mask with reservoir. Intubation should not be attempted in the prehospital stage in most cases. Supraglottic devices such as laryngeal mask airway may provide an alternative in the prehospital setting, or in the event of intubation failure.⁵⁹

Activation of Trauma Team

Recent articles question routine high-level trauma evaluation of pregnant women. A 3-year prospective study reported only 3% of 317 patients with minor trauma had a positive KB test, and only 1 of them had an abruption. The 49 cases (19%) with abruption, PTB, or LBW, could not be predicted based on maternal or injury characteristics or their OB evaluation. These authors argued against extensive evaluation after minor trauma.⁶⁰ Another study evaluated 352 cases and compared trauma activation based on pregnancy only with activation based on other physiologic, mechanistic, and anatomic (OPMA) criteria. In this comparison, 52% of cases were “pregnancy only" and 42% were OMPA. Overall, 94% of injured pregnant women less than 20 weeks were discharged home. No patients in the “pregnancy-only” group were admitted to the trauma service. There were no maternal deaths, but 4 fetal deaths were reported and abruption was diagnosed in only 2%. Surprisingly, 3 cesareans were performed in the “pregnancy only" group. These authors’ opined that trauma team activation based solely on pregnancy resulted in over-triage and a possible misuse of resources.⁶¹ Clearly, more research is needed in this important area.

The typical trauma team is composed of emergency department (ED) and/or trauma physicians and nurses, as well as anesthesia personnel. Many trauma centers advocate simultaneous (not sequential) evaluation of the injured pregnant patient by the trauma and OB team.⁶² An OB physician and nurse should be on standby for secondary assessment, once the patient is stabilized and the initial evaluation is complete. Neonatal equipment, as well as team members able to perform emergent delivery and neonatal resuscitation should be immediately available.

Injury Scoring Systems

Literature is conflicting regarding the ability of trauma scores to predict adverse pregnancy outcomes. Although high injury scores are often associated with high rates maternal or fetal death, low injury scores do not exclude fetal death or other complications. A review of 30 pregnant trauma patients was one of the first to show that the Revised Trauma Score (RTS) did not correlate well with obstetric complications.⁶³ Subsequently, the ISS was evaluated to identify a cutoff to predict poor OB outcomes. In general, a score of 16 or more denotes a severe injury. Records from 294 injured pregnant women with abruption or fetal death revealed ISS ranging from 1 to 34, but most scores were low. Placental abruption occurred in 7%, intrauterine fetal death (IUFD) in 3%, and 3 maternal deaths were reported. A high ISS did not predict abruption or fetal death reliably. However, low ISS scores were nevertheless associated with adverse pregnancy outcomes.⁶⁴

In contrast, 68 patients with an ISS greater than or equal to 12 had an overall fetal mortality of 65%. Blood loss, ISS, abruption, and DIC were all predictors of fetal death.⁶⁵ Also, 271 pregnant patients with blunt abdominal trauma were evaluated and risk factors for fetal death included ISS greater than 9, maternal ejection from vehicle, motorcycle or pedestrian collision, maternal death, maternal tachycardia, lack of restrains, and abnormal FHR.³³ Other studies also support the role of ISS, including a report of 294 women, where maternal age, first trimester, elevated lactate, and high ISS were significant risk factors for poor fetal outcome.² Similarly, a study of 1195 pregnant trauma patients reported independent risk factors for fetal loss included ISS greater than 15, GCS less than or equal to 8, or Adjusted Injury Score greater than or equal to 3 for the head, abdomen, thorax or lower extremities.⁴ Some institutions provide prolonged observation for those with high injury scores, but there is no consensus.

Approach to the Patient

Primary Survey

The initial assessment should take only a few minutes. The ABCDE framework allows for a complete, yet efficient exam and is no different from nonpregnant patients. (See Fig. 18-1.) It is important to stabilize mother first, only then turning attention to the pregnancy and fetus.

Secondary Assessment

After initial stabilization, evaluate for specific maternal injuries and assess fetal well-being. Physical examination for the pregnant trauma patient should include all the same elements as for nonpregnant women, in additional to attention to issues pertaining to pregnancy. Adjunctive laboratory tests should focus on injury patterns related to mechanism of injury, patient complaints, or suspicious findings on exam. A secondary survey includes an early vaginal and rectal examination, with attention to dilation and effacement of the cervix. If vaginal bleeding is present in the second or third trimester, cervical examination should be deferred until sonography excludes placenta previa. Gestational age can be initially estimated by fundal height and is confirmed by bedside ultrasonography. EFM should be performed for at least 4 to 6 hours for patients at viability and beyond. One should not avoid or delay necessary exams due to concerns about fetal radiation exposure. In major trauma, the evaluation usually includes radiographs of chest and other areas as indicated (pelvis, neck, extremities, etc). In nearly all cases, ultrasound (US) is performed, but computed tomography (CT) is also frequently done.

Ancillary Testing

Cardiotocography

Electronic fetal monitoring (EFM) is one of the most sensitive clinical tools for detecting placental abruption after trauma. Continuous EFM is more sensitive in detecting placental abruption than ultrasonography, KB testing, or physical examination. Among women with contractions occurring every 10 minutes or more, the risk of abruption is as high as 20%.⁴⁴ EFM should be a routine part of a trauma evaluation when the fetus is viable (≥23 weeks’ gestation), for at least 4 to 6 hours. Abnormal findings such as contractions more than 6 times per hour or a category II FHR pattern (fetal tachycardia, FHR decelerations, or decreased FHR variability) are potential indicators of higher fetal risk. In this case, continuous monitoring should be extended to 24 to 48 hours. Cesarean delivery should be considered if a category III FHR pattern is identified, or as medically indicated.⁶⁶

Blood tests

Standard laboratory tests for female trauma patients include complete blood count (CBC), basic metabolic panel (BMP) (electrolytes and glucose), type and cross, prothrombin time/partial thromboplastin time (PT/PTT), fibrinogen, Kleihauer-Betke (KB), toxicology screen, and urinalysis (and human chorionic gonadotropin (HCG) if needed). If indicated, arterial blood gas testing should be done if respiratory function is compromised.

Be aware that normal ranges for laboratory results are based on nonpregnant persons. Notable pregnancy-related changes to common test results include: mildly elevated WBC and physiologic anemia. Arterial pH is increased and serum bicarbonate is decreased, as is arterial PCO₂. Maternal fibrinogen levels are increased; in fact, the most sensitive laboratory indicator of abruption is a decreased fibrinogen content. Although some studies question its use, a positive KB test (>0.01% fetal RBC in the maternal circulation) has been associated with PTL by some authors. (Table 18-2)

Ultrasonography

Focused assessment with sonography in trauma (FAST) is performed at the bedside to identify intraperitoneal fluid or pericardial fluid, indicating major organ injury. Bedside US also estimates gestational age, FHR, amniotic fluid volume, and placental position.⁶⁷ FAST can detect many, but not all abdominal or placental injuries. FAST was evaluated in 102 pregnant blunt abdominal trauma patients. FAST identified 4 of 5 patients who went to surgery, but placental injury was missed in one case. Of interest, 96% required no ionizing radiation and 0% required DPL.⁶⁸ Overall, the sensitivity of FAST to detect intra-abdominal injury in pregnancy is 60% to 80% and the specificity is 94% to 100%.⁶⁹ Ultrasound (US) plays a limited role in detecting placental abruption. The appearance depends on the size and location of the bleed and the time between abruption and US examination. Acute abruption has a hyperechoic or isoechoic appearance compared to the placenta, but becomes hypoechoic within 1 to 2 weeks.⁴¹ In fact, US had a sensitivity of only 24% and negative prediction value of only 53% in diagnosing abruption after trauma in one study.⁷⁰ Importantly, pregnancy information gained by US identifies pregnancies that otherwise would receive radiation exposure. At one center, 11% of trauma patients had incidental pregnancy (8% newly diagnosed). Gestational age was earlier and fetal mortality was higher in this group of women. The mean initial radiation exposure for all trauma patients was 4.5 rads in 85% seen at that center.⁷¹

Computed Tomography (CT)

Although ultrasound is more suited for triage of unstable patients, CT is more sensitive than ultrasound to detect organ injury, retroperitoneal hemorrhage, or small amounts of fluid. Multidetector CT (MDCT) is fast, readily available, and facilitates immediate surgery, if needed. CT is the modality of choice for trauma patients; this is also true for pregnant women with suspected intra-abdominal injury. Abdominopelvic CT use during pregnancy increased 22% per year (per 1000 deliveries) from 1998 to 2005, and was used most often to evaluate appendicitis (58%). The average fetal dose from abdominopelvic CT was 24.8 mGy (range 6.7-56 mGy, but 1 examination exceeded 50 mGy). Using a pitch less than 1 and more than 1 series acquisition was associated with a dose of greater than 30 mGy. Thus, attention to technical aspects of image acquisition is important in mitigating potential fetal risk.⁷² A survey of 183 radiology residencies confirmed preference of CT over MRI for evaluating trauma during pregnancy in all trimesters (75%-88% vs 4%-5%).⁷³

Case series suggest that CT may also have a high detection rate for placental abruption. Among pregnant trauma patients, 61 CT studies cited an accuracy of 96% to predict delivery in less than or equal to 36 hours. However, the small number of cases studied and limited clinical details considered preclude definitive conclusions.⁷⁴ In another study, 44 CT scans from pregnant abdominal trauma patients yielded sensitivity and specificity for abruption of 100% and 80%, respectively. The authors speculated that a high false positive rate could be related to differences in experience in interpreting normal placental appearance.⁷⁵ Differentiating normal versus abnormal placental appearance was further explored in a study of 176 pregnant trauma patients with CT scans. Abruption was identified by CT in 61 patients (35%), when viewed by examiners blinded to other clinical data. Intraoperative findings correlated with CT findings in relation to placental perfusion defect. When placental enhancement decreased to less than 50%, clinical signs of abruption reached statistical significance, and the likelihood of delivery due to abruption increased as placental enhancement decreased below 25% to 50% on CT.⁷⁶ While results are encouraging, more study is needed in this area.

Counseling Patients About Risks of Ionizing Radiation

Population-based risks of pregnancy include a 3% risk of spontaneous birth defects, 15% risk of spontaneous abortion, and 1% to 2% risk of mental retardation. The potential for congenital malformations, fetal growth problems, mental retardation, or childhood cancer after in utero ionizing radiation exposure is a concern, but the risks are comparatively small when taken in the context of other aspects of trauma care. Radiation exposure exceeding 0.1 Gy (10 rads) within 2 weeks from conception is associated with high risk for pregnancy wastage, but no increased risk if the embryo survives (ie, the effect appears to be all-or-none). The risk for teratogenesis is highest during the period of organogenesis (2-7 weeks postconception) and early fetogenesis (8-15 weeks postconception). Problems could include microcephaly, microphthalmia, mental retardation, growth restriction, cataracts, and others. Exposure to ionizing radiation during the later fetal period (16 weeks postconception and beyond) may increase the risks for fetal loss, mental retardation, and growth restriction. The radiation dose which may cause birth defects is thought to be approximately 0.05 to 0.15 Gy (5-15 rad). A 2-view chest films delivers a fetal dose of less than 0.0001 Gy (0.01 rad), while a typical pelvic CT delivers about 0.02 to 0.05 Gy (2-5 rads), which are well below the threshold for congenital malformations, but may increase the risk of cancer from a background rate of 0.3% to as high as 1% to 6%.⁷⁷ A simple, qualitative dose assessment has been suggested for providers, in order to determine when a more formal quantitative assessment is needed. Doses are estimated at 2 mGy per exposure for radiographs, 5 mGy per slice for CT, and 10 mGy per minute of fluoroscopy time (when conceptus is in the field). The authors suggest a formal radiation exposure calculation by a medical physicist when the provisional calculation exceeds 10 mGy.⁷⁸

Examples of Protocols and Algorithms

Many hospitals have established protocols for evaluation of pregnant trauma patients. Important elements of standardized care plans include establishing the viability and gestational age of pregnancy and triaging women into risk categories based on injury and obstetric characteristics.

Practice management guidelines were published in 2010 by the Eastern Association for the Surgery of Trauma (EAST) regarding the diagnosis and management of injury in the pregnant patient. Their recommendations are summarized as follows:

• The best initial treatment is optimum resuscitation of the mother and early fetal assessment.

• Keep the patient tilted left side down 15 degrees to prevent aortocaval compression

• All female patients of childbearing age should have a β-human chorionic gonadotropin (β-HCG) screen and be shielded for x-rays when possible

• Concern about ionizing radiation exposure should not prevent medically indicated x-ray procedures from being performed, but other imaging should be considered instead of x-rays when possible.

• Obstetric consult should be considered in all cases of injury in pregnant patients.

• All pregnant women greater than 20 weeks’ gestation who suffer trauma should have cardiotocographic monitoring for a minimum of 6 hours. Monitoring should be continued and further evaluation should be carried out if uterine contractions, nonreassuring FHR pattern, vaginal bleeding, significant uterine tenderness or irritability, serious maternal injury, or rupture of the amniotic membranes is noted.

• Kleihauer-Betke analysis should be performed in all pregnant patients greater than 12 weeks’ gestation.

• Perimortem cesarean section should be considered in any moribund pregnant woman at greater than or equal to 24 weeks’ gestation. Perimortem cesarean delivery must occur within 20 minutes of maternal death but ideally should start within 4 minutes of maternal arrest. Fetal neurologic outcome is related to delivery time after maternal death.⁷⁹

A proposed algorithm for evaluation and management of trauma in pregnancy is shown in Fig. 18-2. A basic approach to obstetric management is detailed below. Decisions about route and timing of delivery should be based on usual obstetric considerations within the context of treatment plans for other maternal injures.

Brief observation (4-6 hours) is sufficient if

• Maternal trauma is minor.

• Mother is hemodynamically stable.

• Primary evaluation is negative.

• FAST-US is negative for intra-abdominal fluid.

• No obstetric complaints are found.

• Fewer than 6 contractions per hour occur.

• It is category I FHR pattern.

• Examination and laboratory data are normal.

Prolonged observation (24-48 hours, with continuous EFM) strongly advised if

• Multiple or severe maternal injuries occur.

• Mother is hemodynamically unstable.

• Obstetric symptoms present (regular contractions, vaginal bleeding, vaginal leakage, pain).

• Contractions greater than 6 per hour occur during first 4 to 6 hours.

• FHR pattern on EFM is abnormal.

• Examination is abnormal (eg, fundal tenderness, cervical dilatation ≥2 cm).

• Laboratory data are abnormal (eg, +KB, abnormal fibrinogen).

• Imaging studies are abnormal (eg, FAST US, abnormal OB ultrasound, short CL, abnormal CT).

Other considerations

Rh Immune Globulin

All eligible Rh-negative patients should receive Rh immune globulin (RhIG) 300 μg IM within 72 hours of an episode of trauma, in order to prevent maternal sensitization. For women with a positive KB test, additional RhIG can be administered, with an additional 300 μg for each 30 mL of fetal RBCs in the maternal circulation. For Rh-negative women with confirmed (FMH), additional RhIG may be needed. To estimate the volume of fetal blood loss into the maternal circulation, several formulae exist, but the basic equation is as follows⁴⁵:

• The newborn Hct is often assumed to be 45% to 50%.

• Maternal blood volume is assumed to be 5000 to 5800 cc.

Tetanus Prophylaxis

Tetanus is a rare, potentially fatal disease caused by the anaerobe, Clostridium tetani. Wounds that are crushed, devitalized, or contaminated with dirt or rust are considered to be tetanus-prone. Open fractures, punctures, and abscesses are also associated, but severity of the wound does not determine the risk. All wounds should be cleaned and debrided, if necessary.

Tetanus toxoid should be given if the last booster was more than 10 years prior for clean, minor wounds, or more than 5 years prior for all other wounds. If the history of tetanus immunization is unknown or less than 3 prior doses, tetanus toxoid (Td) is indicated. Tetanus toxoid (Tdap may be used), but a single dose of Tdap should be provided in place of one Td booster if the patient has not previously received Tdap. Passive immunization with Tetanus immune globulin is indicated (≥250 IU) in persons with other than clean, minor wounds and a history of no, unknown, or less than 3 previous tetanus toxoid doses. Tetanus immune globulin can only help remove unbound tetanus toxin. It cannot affect toxin bound to nerve endings. Part of the tetanus immune globulin (TIG) dose should be infiltrated around the wound. Intravenous immunoglobulin (IVIG) contains tetanus antitoxin and may be used if TIG is not available.⁸⁰

Cardiopulmonary Resuscitation and Perimortem Cesarean

Aspects of CPR During Pregnancy

In rare cases, pregnant women may have life-threatening injuries requiring cardiopulmonary resuscitation (CPR) and advanced cardiovascular life support (ACLS) procedures. There should be no delay in administering CPR, but there are several modifications for pregnant patients which may improve resuscitation efforts. The woman’s torso should be tilted 15 to 30 degrees from the left lateral position. Alternatively, a wedge can be placed under the woman’s right side, or one rescuer can kneel next to the woman’s left side and gently displace the gravid uterus laterally. There are no modifications in defibrillation dose or pad position. If possible, remove any fetal or uterine monitors prior to delivering a shock. The airway should be secured early, using continuous cricoid pressure before and during intubation attempts. The endotracheal tube (ETT) may need to be 0.5 to 1 cm smaller in diameter than that used for a nonpregnant woman of similar size, due to airway edema. If possible, use an exhaled CO₂ detector to confirm ETT placement. Reduce ventilation volumes, since the mother’s diaphragm is elevated by the gravid uterus. Follow usual ACLS guidelines for medications used in ACLS protocols. Although vasopressors decrease uterine blood flow, there are no alternative agents or regimens. Consider potentially reversible causes of cardiac arrest when approaching the gravid patient. In addition to the same causes seen in nonpregnant patients, one must consider other factors such as magnesium toxicity, eclampsia, acute coronary syndromes, aortic dissection, pulmonary embolism, stroke, amniotic fluid embolism, and drug overdose.⁸¹ CPR and ACLS are discussed in further detail elsewhere in this textbook.

Perimortem Cesarean

Cesarean delivery can be life-saving for both mother and fetus. Survival rates and the risks for long-term impairment depend on the gestational age and the interval from cardiac arrest to delivery. The recommendation to perform perimortem cesarean delivery (PMCD) within 4 minutes of maternal cardiac arrest was first made in 1986.⁸² A follow-up study of 38 cases of PMCD resulted in 34 surviving infants, including 3 sets of twins and 1 set of triplets. Eleven women were delivered within 5 minutes, and 6 within 15 minutes, but 7 were delivered over 15 minutes after maternal arrest. PMCD likely improves results of maternal resuscitation. PMCD preceded return of maternal pulse and blood pressure in 12 of 18 cases where specifics could be reviewed and 8 other mothers showed an overall improvement after PMCD. Among 20 cases with “resuscitatable” causes for cardiac arrest, 13 mothers recovered and were later discharged in good condition.⁸³ Alleviating vena cava compression and improving ventilation by emptying the gravid uterus may account for the beneficial effects of PMCD. A review of all reported cases of cardiac arrest in 1980 to 2010 yielded 94 cases, with 54% who survived to hospital discharge. PMCD was beneficial to the mother in 32% of cases and not harmful in any case. In-hospital arrest and PMCD within 10 minutes of arrest were associated with better maternal outcomes. Neonatal survival was only associated with in-hospital cardiac arrest.⁸⁴

Team Drills and Simulation Training for CPR and PMCD

Team drills and simulations can provide insight into performance issues or gaps in knowledge and skills. For example, transporting a gravid patient with cardiac arrest decreases the quality of CPR. Among 26 teams of 2 providers performing CPR on a mannequin, only 32% were able to correctly perform chest compressions when CPR was done while transporting versus 93% when stationary. Interruptions were common and tidal volume was suboptimal when CPR was done during transport.⁸⁵ Simulation followed by oral debriefing was also studied in 25 anesthesiology residents. They simulated care for maternal cardiac arrest due to magnesium toxicity and preeclampsia. Although general aspects were performed well, OB-related interventions were performed poorly. Features of OB care, including uterine displacement, cricoid pressure, treatment of magnesium toxicity, and initiation of PMCD by 4 minutes, were all suboptimal. Oral debriefing highlighted and addressed gaps in knowledge about adaptations to ACLS for pregnant women.⁸⁶

Simulations also demonstrate an advantage to PMCD being performed in the labor room. A trial involving 15 teams simulated PMCD in the labor room versus transporting to the operating room (OR). The median time to incision was 4:25 when PMCD was in the labor room, versus 7:53 after going to the OR. (Only 57% of labor room teams and 14% of OR teams achieved delivery within 5 minutes.) Faster were times to defibrillation, NICU contact and maternal intubation were also seen when remaining in place.⁸⁷ Recently, simulation training for PMCD was described using a model for a gravid uterus, where residents were expected to perform PMCD and resuscitate the newborn. Debriefing followed the scenario, including indications and technique for PMCD. All participants strongly agreed that the session enhanced learning more than lectures and readings alone.⁸⁸ Indeed, advanced staff training about maternal CPR and PMCD appears to affect patient outcomes. Data from the Netherlands over a 15-year period showed that 55 women had cardiac arrest, of whom 12 underwent PMCD. The Managing Obstetric Emergencies and Trauma (MOET) course was initiated in 2004; subsequent practice patterns indicate increasing use of PMCD. Prior to the MOET course, 4 PMCS were done (0.36/y) compared with 8 cases after (1.6/y). Eight of 12 women treated with PMCD regained cardiac output, with 2 maternal and 5 neonatal survivors.⁸⁹

Crash Tests and Pregnancy

Specialized crash tests have characterized the effects of MVC on the pregnant uterus. These studies confirm that pressure gradients occur in the gravid uterus during a vehicular crash, due to inertia of the amniotic fluid and strain at the uteroplacental interface. The first actual crash tests were conducted using a prototype pregnant dummy with a 28-week sized fetus in the 1990s. Increasing crash speed correlated with higher forces in the uterus. When the lap belt was placed improperly onto the uterus, the force transmitted through the uterus was 3 to 4 times higher. There was significant energy transmission when the airbag deployed without restraints, or when the uterus was positioned close to the airbag.^90,91 Other studies using a gravid “dummy” evaluated uterine strain during crash conditions of being unrestrained, using a 3-point belt, or 3-point belt plus airbag. Uterine wall strain was excessive if no restraints at 35 km/h or when using a 3-point belt at 45 to 55 km/h. The safest scenario was involved using both the 3-point belt and airbag.⁹² More recently, crash tests evaluated front or rear impacts. In a frontal crash without restraints, the abdominal pressure peaked where the dummy contacted the steering wheel. In a rear impact without seat belt, the dummy moved forward and also contacted the steering wheel. Seat belt use either reduced abdominal pressure, or prevented contact with the steering wheel altogether.⁹³

Seat Belts and Airbags

Most clinical studies affirm that use of seat belts and airbags reduces the chance of maternal injury and fetal loss after MVCs. An in-depth investigation of 57 crashes with pregnant occupants revealed that fetal outcome was most strongly associated with crash severity and maternal injury. Proper maternal seat belt/restraint use (with or without air bag deployment) was associated with a 4 to 5 times higher odds of good fetal outcome. The authors estimated that 50% of fetal losses after MVCs could be prevented if all pregnant women wore seat belts properly.⁹⁴ Among 8938 Utah mothers (2.8% of live births) who reported an MVC during pregnancy, there was no higher risk for poor fetal outcome than gravidas who were not in crashes, provided they used seat belts. Women not using seat belts during a crash were 1.3 times more likely to have a LBW infant than those not in a crash and twice as likely to have excessive maternal bleeding than belted women in crashes. Forty-five of 2645 fetal deaths were linked to MVCs; unbelted women had a 28-fold higher risk of fetal death.⁹⁵

The literature is less consistent regarding the risks and benefits of air bags during pregnancy. Airbags were developed for males, but for females airbags are protective only when speeds are greater than about 35 mi/h. At lower speeds, the risk for injury exceeds the benefit. “Advanced air bags” are reportedly safe for children and women. Nonetheless, the sternum of pregnant women should be at least 10 in from the dashboard or steering wheel, and the seat should be moved back as the uterus grows.²⁰ A chart review of 2 urban emergency departments of women over 20 weeks with MVC and airbag deployment identified 30 women in 6 years. One woman had abruption and IUFD, 73% had uterine contractions, 53% had abdominal pain, 20% had abnormal FHR and 7% experienced vaginal bleeding. It was unclear whether fetal risk was higher than without air bags.⁹⁶ A retrospective study evaluated pregnancies after MVC in Washington State from 2002 to 2005. No increased risk of adverse maternal or perinatal outcomes was seen among those with airbag equipped vehicles in all 2207 collisions studied (compared to vehicles without airbags). Based on crash characteristics, if airbag deployment was likely, there was a 70% increase in PTL risk and 3-fold increase in IUFD, but these were not statistically significant.⁹⁷

Education About Seat Belts

A Centers for Disease Control and Prevention (CDC) survey from 19 states reported that prevalence of seat belt use among reproductive aged women was 70% to 91%. Older, white, and educated women reported using seat belts more often. Counseling to wear seat belts ranged from 37% to 57% during pregnancy and was more often reported by younger, black, and less educated mothers.⁹⁸ Seat belt use, counseling, and motor vehicle accidents (MVA) injury were also studied in 22 states using CDC PRAMS data from 2001. Women most likely to report counseling were 20 to 29 years, nonwhite, Hispanic and less educated. Women older than 30 years and with high education were most likely to report always wearing a seat belt. The authors estimated that 92,500 pregnant women are hurt annually due to MVCs in the United States. However, a slight majority (51%) stated they were not counseled about seat belts during prenatal care.⁹⁹ Educational materials for prenatal care clinic patients and staff regarding seat belt use during pregnancy have been studied via pre- and post-test surveys. Most (60%) thought restraints protect their baby during a collision, while 12% thought restraints cause injury, and 37% were unsure. Reasons for not using seat belts were discomfort (53%) and forgetfulness (43%). Correct placement of seat belts increased from 71% to 83% after intervention. Only 37% recalled receiving information during their prenatal care about seat belts.^100,101

Women should be advised to place their lap belt low across the hips and under the maternal abdomen. The shoulder harness should lay between the breasts and over the midline of the left clavicle. Airbags should not be disabled due to pregnancy, but the abdomen should be 10 in or more away from the air bag. Prenatal care visits and emergency room encounters provide an opportunity for providers to give health messages to their pregnant patients regarding the importance of proper seat belt use.

Reducing Intimate Partner Violence

An RCT studied outcomes of 1044 women assigned to receive either individually tailored counseling sessions (social worker or psychologist) or usual prenatal care. The intervention provided women with suggestions to deal with depression and tobacco use, and cognitive behavioral strategies to reduce the risk for IPV. Women in the intervention group were half as likely to have recurrent episodes of IPV. Women in the intervention group also had fewer preterm infants (1.5% vs 6.6%). The number needed to treat ranged from 17 to 27, potentially making this an effective strategy.¹⁰²