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Trauma in pregnancy: Diagnosis and management of two patients in one

Wyant, Andrew R. MD; Collett, DeShana MSPAS, PA‐C

Journal of the American Academy of Physician Assistants: May 2013 - Volume 26 - Issue 5 - p 24–29


* Identify the most common causes of maternal trauma and secondary obstetric complications

* Recognize key predictors of adverse fetal outcome in significant maternal injury

* Discuss the development of unrecognized shock in the injured mother as well as proper diagnosis and potential sequelae

Because maternal hemodynamic parameters do not accurately predict fetal distress, concurrent fetal assessment and maternal stabilization is necessary.

Both authors are assistant professors in the Division of Physician Assistant Studies at the University of Kentucky, College of Health Sciences, in Lexington. Andrew Wyant has experience practicing as both an obstetrician/gynecologist and emergency room physician. DeShana Collett practices family medicine at Lexington Clinic.

No relationships to disclose.

Trauma impacts 6% to 7% of all pregnancies regardless of gestational age.1,2 This translates to approximately 350,000 to 500,000 pregnant women affected yearly in the United States alone. Trauma is the leading cause of nonobstetric morbidity and mortality in pregnant women.3 Maternal morbidity refers to any injury or disease sustained by a woman while pregnant. Maternal mortality is defined as death of a female who is pregnant or less than 43 days postpartum. Statistics on maternal and perinatal mortality associated with major traumatic injury vary, but numbers as high as 10% and 60%, respectively, have been reported.4 Blunt trauma (82%) is far more common than penetrating trauma (18%).5 Motor vehicle accidents (MVAs) have been the leading cause of traumatic injury in pregnancy, resulting in 1,300 to 13,000 fetal deaths per year.6 Adverse maternal and perinatal outcomes are frequently related to inappropriate use of seatbelts or other restraints7 (Figure 1). Recent studies confirm a dramatic rise in intimate partner violence (IPV), opening the possibility that it may exceed falls as the second most common cause of traumatic injury in pregnant women.5 Obstetric complications following maternal trauma include preterm labor (PTL), placental abruption (PA), premature rupture of membranes (PROM), uterine rupture, fetal‐maternal hemorrhage, fetal demise, and maternal‐fetal death.8 Although uterine rupture is exceedingly rare, it is associated with a near 100% fetal mortality rate.3,7 Prompt posttrauma assessment of both mother and fetus is necessary because findings in the mother may not indicate the severity of injury to the baby.

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Trauma is the leading nonobstetric cause of maternal mortality, accounting for as much as 46% of all maternal deaths.9 Significant trauma is present in approximately one in 12 pregnant women admitted to inner‐city hospitals in the United States.5 MVAs account for most cases of blunt trauma (70%).3

In many studies, IPV has replaced falls as the second most common cause of maternal injury.5 Some cohorts have shown the percentage of pregnant women who have experienced physical or sexual IPV by a male partner to be as high as 9% (range, 1.2%‐9%).10 This may be attributed to the rising presence of women in the workforce during pregnancy and an increasingly violent society.7 Most commonly, violence falls into one of four categories of abuse: physical, sexual, psychological/emotional, and economic,11 and the intimate partner may be anyone with whom the victim shares a relationship. Stress, poverty, limited education, lower income and wealth, and lack of exposure to social norms increase the risk of IPV.12,13 Pregnancy within the past 12 months doubles the risk of IPV,14 and pregnant women have a threefold risk of becoming a victim of homicide.15

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As a pelvic organ, the uterus is shielded during the first trimester, and from 13 to 23 weeks of gestation, the fetus is somewhat protected by the cushion effect of the amniotic fluid. In the third trimester, the uterine wall evolves into a thinner‐walled organ and its position in the upper abdomen increases the risk of such obstetric complications as penetrating trauma, PROM, PA, and uterine rupture.4 The risk of PA is increased because of the relative inelasticity of the placenta compared with the elastic uterine wall. Higher uterine pressures and shear resulting from blunt force increase the likelihood of tearing the placenta from the uterine wall.7 Anatomic changes from pregnancy may also potentiate obstetric comorbidities.

During pregnancy, the maternal heart rate increases to 15 beats per minute above the prepregnancy baseline. BP drops to a nadir of 15 mm Hg below baseline by the end of the second trimester. Cardiac output is increased by 1 to 1.5 L per minute over baseline, and the total blood volume is increased by 50% above normal. The RBC mass does not increase by as much as the volume, resulting in a dilutional anemia. These unique cardiovascular adaptations present both an advantage and a disadvantage.7 The hyperdynamic and hypervolemic adaptations benefit the pregnancy by meeting metabolic demands but may lull the clinician into a false sense of security when minimal, if any, change in pulse or BP is present with ongoing maternal shock.16

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Intimate partner violence Evidence indicates that IPV can be an independent significant risk factor for adverse pregnancy outcomes. Women who reported IPV during the prenatal period had a risk of clinical pregnancy trauma greater than 30 times that of women who did not report IPV (P<.01) and five times the odds of experiencing PA (P <.05).10 Other studies have suggested a positive correlation between physical abuse and adverse outcomes, such as antepartum hemorrhage, PA, intrauterine growth retardation, and fetal mortality.10,11,15 Women exposed to IPV were 50% more likely to experience fetal demise.17 IPV is responsible for an increasing percentage of PA.4

Placental abruption Second only to maternal death in causing the demise of the fetus, PA is the most common obstetric complication of trauma and a frequent cause of PTL. Premature separation of the placenta occurs in 5% of patients with minor trauma and 20% to 50% of those with major trauma.18 More than 70% of fetal losses following blunt trauma result from PA, making accurate and timely diagnosis crucial.4 Clinically, PA varies with the degree of detachment. Classic symptoms are vaginal bleeding, pain in the back or abdomen, fundal tenderness, fetal distress, and frequent contractions (PTL), all of which can range from absent to severe. Vaginal bleeding may be massive or concealed, and abdominal symptoms may range from marked uterine tenderness to absent. These variations in clinical presentation hinder accurate and timely diagnosis. Occult PA is diagnostically challenging and may be detected only by fetal heart rate (FHR) tracing or by ultrasound (US) examination. Even with the best US examination, sensitivity for detecting occult PA is 50%.19,20 Disrupted uteroplacental blood flow causes fetal asphyxia, leading to decelerations in FHR, fetal bradycardia, and frequent uterine contractions.

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- Hyperdynamic and hypervolemic adaptations benefit the pregnancy by meeting metabolic demands but may lull the clinician into a false sense of security when minimal, if any, change in pulse or BP is present with ongoing shock. IPV is responsible for an increasing percentage of placental abruption (PA).

- Anatomic and physiologic changes of pregnancy can mask shock in the mother, delaying diagnosis of uteroplacental insufficiency and contributing to fetal morbidity.

- Cardiotocographic monitoring is the most sensitive indicator of fetal distress and is universally recommended as the gold standard following maternal trauma, regardless of severity or location of injury. Cardiotocography is highly sensitive for detecting PA, fetal death, preterm contractions, and fetal distress.

Blunt abdominal trauma Perinatal mortality following blunt abdominal trauma for any reason ranges from 3.5% to 38% and usually results from PA, maternal shock, or maternal death.4 Clinically evident PA occurs in 40% of women who experience severe blunt abdominal trauma and 3% of those who experience minor abdominal trauma.7 Diagnosis is based on clinical grounds, FHR decelerations on fetal monitoring, and possibly a retroplacental clot on US.20 Studies have indicated that a WBC count of greater than 20,000/mm3 indicates PA in more than 50% of cases and may be a very early clinical predictor of abruption.21

Increased vascular congestion associated with pregnancy results in a higher incidence of splenic and retroperitoneal bleeding with blunt force injury. Due to displacement by the gravid uterus, intestinal rupture is less common.22 Direct fetal injuries, such as skull fractures, are rare in maternal blunt trauma, complicating less than 1% of such cases.16 Obstetric complications after apparent minor injury have led many to speculate that direct uterine blunt‐force trauma (however minimal), especially after 35 weeks’ gestation, may be an important independent risk factor.5

Penetrating trauma Gunshot and knife wounds are the most common forms of penetrating injury. A trauma surgeon should be consulted immediately for likely exploration. Delivery by cesarean section should be considered on a case‐by‐case basis.4

Maternal shock Anatomic and physiologic changes of pregnancy can mask shock in the mother, delaying diagnosis of uteroplacental insufficiency and contributing to fetal morbidity. Altered maternal physiology (baseline tachycardia, tachypnea, physiologic anemia) can allow fetal hypoxia from unrecognized maternal shock to go undiagnosed, hence the importance of astute clinical awareness and preemptive fetal testing. The physiologic alterations in heart rate and BP that occur with pregnancy may result in underestimation of blood loss during initial evaluation of the trauma victim.7 Blood loss may be as great as 2,000 mL without any change in vital signs. Under normal conditions, the uteroplacental vasculature is fully dilated, but maternal hypovolemia leads to adrenergic vasoconstriction of uterine vessels and shunting of blood flow away from the fetus. This results in FHR abnormalities (FHR decelerations or decreased variability) and is an early indicator of both fetal distress and maternal hemodynamic status (Figure 2). Fetal hypoxia may be well under way with no change in vital signs.

Studies have indicated that maternal hemodynamic parameters do not accurately predict fetal distress and are not independent risk factors to predict fetal loss.9 This undergirds the importance of early and aggressive fetal assessment concurrent with maternal stabilization. Unrecognized maternal shock has resulted in fetal demise in the setting of minor blunt abdominal trauma. Early fetal monitoring may reveal FHR changes as the first indicator of maternal hypovolemic shock. Understanding the important anatomic and physiologic changes of pregnancy should help clinicians recognize occult shock.


The most significant prognostic factor for fetal well‐being is maternal status: thus, the dictum to stabilize the mother first, then assess the fetus. Pregnant patients who present with reassuring initial hemodynamic parameters and laboratory profiles following minor trauma have rates of fetal complications ranging from 5% to 25%.20 Typical obstetric signs of concern, such as vaginal bleeding, leakage of amniotic fluid, contractions, and uterine tenderness, are solid predictors but are often absent.

Other risk factors Classically reported risk factors that have been shown to be predictive of fetal death are absent fetal heart tones, Injury Severity Score (ISS) greater than 9, maternal death, and PA in maternal survivors. In retrospective studies using univariate analysis, however, the only two independent predictive indicators for fetal loss were an ISS greater than 9 and gestational age of less than 23 weeks.9 The ISS is an objective evaluation of traumatic injury based on regional anatomic acute injury.20 Each of six major body systems is assigned a numerical score based on severity of injury, producing an abbreviated injury score (AIS). The three highest AIS are then squared and added together to calculate the ISS, which can range from 0 to 75. An ISS greater than 9 is highly predictive of fetal distress. A sample calculation of the ISS is presented in Table 1. One point of concern is that 50% of patients who suffered fetal loss had no evidence of abdominal injury (AIS = 0) on the ISS. This finding reinforces the possibility that the neurohormonal effect of maternal shock may independently contribute to fetal demise.9

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Although the ISS is a predictor of fetal loss, fetal death has occurred in moderate injury and even in trivial abdominal injuries (albeit rarely); this fact demands that fetal monitoring be performed regardless of the severity or location of maternal injuries. Cardiotocographic monitoring is the most sensitive indicator of fetal distress and is universally recommended as the gold standard following maternal trauma, regardless of severity or location of injury. Cardiotocography is highly sensitive for detecting PA, fetal death, preterm contractions, and fetal distress. The weight of the evidence indicates that monitoring for 4 hours in the gestational age of greater than 20 to 23 weeks is adequate to ensure fetal well‐being.23 The previous standard was to monitor for 48 hours after maternal trauma. However, Pearlman and colleagues recommended a minimum of 4 hours of monitoring in women at greater than 20 weeks' gestation.24 Some studies have indicated that adverse outcomes usually manifest within 4 to 6 hours of the traumatic event.20 Other studies have revealed that patients who were monitored for 4 hours, were having fewer than four contractions per hour, and had no abnormalities in FHR were discharged home with no late maternal or fetal complications. Solid evidence now indicates that fetal monitoring should be initiated as soon as possible concurrent with maternal resuscitation in patients with a gestational age of 20 weeks or more and continue for 4 hours post trauma. A reassuring FHR pattern and fewer than 4 contractions per hour are grounds for safe discharge.7 Guidelines will be suggested based on retrospective data.9

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Females involved in trauma should be stratified as follows: (1) potentially pregnant, (2) less than 23 weeks pregnant, when fetal viability is unlikely; (3) greater than 23 weeks pregnant, when treatment is aimed at both maternal stabilization and early fetal evaluation; (4) perimortem state, when emergent cesarean delivery may result in infant salvage but maternal recovery is futile.

Management of “two patients in one” should follow trauma guidelines as outlined in Figure 3, with attention to the following: (1) maternal resuscitation in the left lateral tilt position, (2) emergent fetal assessment by Doppler and fetal monitoring for a minimum of 4 hours, and (3) early US for fetal well‐being and age. Initial evaluation must include a rapid and focused obstetric and gynecologic history. Emergent fetal monitoring may be the earliest indication of ongoing occult maternal shock.

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Treatment of trauma in a pregnant patient requires a high index of suspicion for maternal and fetal complications as well as an integrated team‐based approach for optimal outcomes. Because outcomes range from trivial to catastrophic and are difficult to predict, pregnant patients exposed to trauma require early fetal assessment with fetal heart tones using Doppler, fetal monitoring and early US, and aggressive maternal resuscitation. Evidence suggests that early fetal evaluation and a minimum of 4 hours of fetal monitoring are indicated for all pregnant patients to prevent complications and fetal loss. Placental abruption from blunt abdominal trauma and particularly IPV should carry a high index of suspicion.

Research indicates that IPV is wholly preventable. Screening and adequate treatment of IPV are key components to decreasing the incidence of IPV. Several screening instruments are available for clinician use, including the Women Abuse Screening Tool (WAST), Abuse Assessment Screen (AAS), and Hurt‐Insult‐Threaten‐Scream (HITS) tool. The CDC describes several IPV assessment tools for use in the health care setting.25 In addition, the Look to End Abuse Permanently Web site provides self‐administered assessments and patient education materials that can be used in various clinical settings and highlight the importance of health literacy, mandatory state reporting laws, and guidelines for screening. Providing screening at every prenatal encounter and ED visit will vastly increase opportunities for identifying IPV.

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Section Description

EARN CATEGORY I CME CREDIT by reading this article and the article beginning on page 54 and successfully completing the posttest on page 58. Successful completion is defined as a cumulative score of at least 70% correct. This material has been reviewed and is approved for 1 hour of clinical Category I (Preapproved) CME credit by the AAPA. The term of approval is for 1 year from the publication date of May 2013.

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