Initial evaluation and management of major trauma in pregnancy

INTRODUCTION — Evaluation of the pregnant trauma patient presents unique challenges since the presence of a fetus means that two patients are potentially at risk, both of whom require evaluation and management. Major trauma may be defined as an injury that has the potential to be life-threatening or life-changing. In the pregnant person, compression of the abdomen from a fall, intentional violence, or a low-speed motor vehicle crash can be considered major trauma since it has the potential to cause abruption, which can be life-threatening for the mother and/or fetus.

This topic will discuss issues specific to the pregnant patient with major trauma. Issues related to management of trauma in the nonpregnant population are reviewed separately. (See "Initial management of trauma in adults".)

PREVALENCE — Trauma affects 6 to 8 percent of pregnancies [1]. Motor vehicle crashes, falls, and assault are the most common causes [2]. A systematic review of studies on trauma in pregnancy reported the following estimates of trauma prevalence by subtype of trauma [3]:

●Domestic/intimate partner violence – 8307/100,000 live births

●Motor vehicle crash – 207/100,000 live births

●Falls – 49/100,000 live births

●Homicide – 3/100,000 live births

●Penetrating trauma – 3/100,000 live births

●Suicide – 2/100,000 live births

●Toxic exposure – 26/100,000 person-years

●Burns – 0.17/100,000 person-years

PREGNANCY-RELATED CHANGES IN PHYSIOLOGY — Physiological changes related to pregnancy occur in virtually all systems and are caused by both hormonal and mechanical factors. These normal changes need to be considered when evaluating the status of pregnant trauma victims. Pertinent changes in major organ systems are summarized below; in-depth reviews of each organ system can be found separately.

●Cardiovascular — Cardiac output (CO) increases by 20 percent at eight weeks of gestation and continues to rise until 30 to 32 weeks, at which point it plateaus at approximately 50 percent above baseline until the beginning of labor. The rise in CO is due to:

•Increased preload from a rise in blood volume (figure 1).

•Decreased afterload from declining vascular resistance (figure 2).

•Increased maternal heart rate, by 15 to 20 beats per minute (figure 3).

Supine position at term can lower CO by 25 to 30 percent compared with left lateral decubitus position, due to compression of the inferior vena cava by the gravid uterus (figure 3).

Cardiac flow murmurs are very common in pregnancy secondary to increased cardiac output. Thus, an isolated murmur in an otherwise stable pregnant trauma patient is not likely to reflect an acute cardiac injury.

Pregnancy related, normal ECG findings include:

•15 to 20° left axis deviation.

•Transient ST segment and T wave changes.

•Q wave and inverted T waves in lead III, an attenuated Q wave in lead AVF, and inverted T waves in leads V1, V2, and, occasionally, V3.

(See "Maternal adaptations to pregnancy: Cardiovascular and hemodynamic changes".)

●Pulmonary — Pregnancy-related pulmonary changes include:

•Beginning in the first trimester, increases in tidal volume and respiratory drive (due to the stimulatory effects of progesterone) cause hyperventilation and a chronic respiratory alkalosis (figure 4 and table 1). The compensatory fall in the plasma bicarbonate concentration diminishes its buffering ability.

•PaO₂ may be slightly elevated at 104 to 108 mmHg as a result of the increase in CO and less ventilation-perfusion mismatch in the lung.

•Beginning at approximately 20 weeks of gestation, upward displacement of the diaphragm leads to a 20 percent decrease in functional residual capacity.

•Oxygen consumption increases by almost 20 percent.

(See "Maternal adaptations to pregnancy: Dyspnea and other physiologic respiratory changes".)

●Hematologic — Pregnancy-related hematologic changes include:

•Plasma volume increases by 50 percent by 32 weeks of gestation.

•Total red blood cell mass increases only by 20 to 30 percent, resulting in hemodilution ("physiologic anemia of pregnancy"), with normal hemoglobin levels as low as 11 g/dL in the first and third trimesters, and 10.5 g/dL in the second trimester (figure 1).

•Mild leukocytosis (6000 to 16,000 cell/mm³).

•Small reduction in platelet count, which typically remains within the normal range.

•Pregnancy is a procoagulant state. A variety of changes occur in procoagulant and anticoagulant pathways, which on balance increase coagulation potential on a background of reduced anticoagulation and fibrinolysis. The normal fibrinogen concentration is greater than 400 mg/dL.

(See "Maternal adaptations to pregnancy: Hematologic changes".)

●Gastrointestinal — Pregnant people are at high risk of gastric aspiration, most likely related to decreased lower esophageal sphincter tone and increased intraabdominal pressure. Gastric emptying is not affected by pregnancy, though it is slowed by labor and opioid analgesics. (See "Maternal adaptations to pregnancy: Gastrointestinal tract".)

●Renal — Glomerular filtration rate and renal blood flow rise markedly during pregnancy, resulting in a physiologic fall in the serum creatinine concentration to 0.4 to 0.5 mg/dL (35 to 44 micromol/L). (See "Maternal adaptations to pregnancy: Renal and urinary tract physiology".)

●Uterus — Major changes to the uterus and its vascular supply occur in pregnancy:

•For the first 12 weeks of pregnancy, the uterus is a pelvic organ and thus protected from external injury by the bony pelvis. Further uterine enlargement into the abdomen after 12 weeks makes it more vulnerable to injury.

•The enlarged uterus reduces the risk of visceral injury after lower abdominal penetrating injuries by displacing the bowel cephalad and laterally, whereas penetrating injuries above the uterine fundus are likely to damage the bowel for the same reason [4].

•The pelvic vasculature is dilated in pregnancy. Injury to the dilated pelvic vasculature can result in rapid exsanguination [5].

•Uterine blood flow is as high as 600 mL/minute in the third trimester and not autoregulated, thus a decrease in maternal systolic blood pressure can cause a significant fall in blood flow, and in turn, fetal oxygenation.

INITIAL EVALUATION AND MANAGEMENT OF MAJOR TRAUMA

General principles

●Definition of major trauma – The approach to evaluation and management of trauma in pregnant patients is dictated by its severity and influenced by the gestational age. The following discussion refers to pregnant patients who have experienced major trauma. Optimal care of trauma patients requires good communication among a multidisciplinary group of clinicians [6,7]. Major trauma is defined in various ways, but typically takes into account the risk of death or impairment, need for hospital or complex resources for treatment, impact on quality of life, and need for prolonged recovery. In pregnancy, major trauma can include compression of the abdomen from a fall, intentional violence, or a low-speed motor vehicle crash since it has the potential to cause abruption, which can be life-threatening for the mother and/or fetus.

●Obstetric consultation and estimation of gestational age – The obstetric service should be consulted simultaneously with other specialties to help with the evaluation and to determine whether emergency cesarean birth is indicated.

A simple, quick, and crude method for estimating gestational age is to determine the location of the uterine fundus: If below the umbilicus, pregnancy duration is likely less than 20 weeks of gestation; if at or above the umbilicus, pregnancy duration is likely greater than 20 weeks. Another quick way to determine fetal gestational age crudely is by measuring the fetal femur length with a focused obstetric ultrasound: If the femur is ≥4 cm, the fetus should be considered viable as this suggests a gestational duration of 22 to 24 weeks [8,9]. This information is important because:

•Consideration of cesarean birth specifically for maternal resuscitation is only warranted if the uterus is above the umbilicus because a uterus this large can compress the vena cava and impede maternal resuscitation. It should be performed if cardiopulmonary resuscitation is unsuccessful by four minutes. (See 'Circulation' below.)

•Cesarean birth for fetal indications is only warranted if pregnancy duration is at least 22 to 23 weeks, which is the lower limit of neonatal viability. Cesarean birth when the uterus is below the umbilicus or the fetal femur is less than 4 cm almost never benefits the neonate. (See 'Determining gestational age' below and "Periviable birth (limit of viability)".)

●Choice of diagnostic tests and treatments – Any diagnostic test or treatment required to save the mother's life or treat their critical status should be undertaken, even if such intervention is potentially disadvantageous to the fetus. In most cases, short- and long-term morbidity in surviving fetuses are related to the direct and indirect consequences of maternal trauma (eg, hypotension, hypoxemia, placental abruption, preterm birth), so accurate maternal diagnosis and appropriate maternal treatment can significantly impact the fetus. However in cases of direct fetal injury, the fetal injury may be more serious than the maternal injury [10].

●ABCs – As in any trauma patient, the initial goal is to assess the airway, breathing, and circulation (ABC) and, when appropriate, establish cardiopulmonary stability (algorithm 1) [11]. (See "Adult basic life support (BLS) for health care providers" and "Advanced cardiac life support (ACLS) in adults" and "Sudden cardiac arrest and death in pregnancy".)

Airway, breathing, and ventilation

●Maintain oxygen saturation >95 percent – Oxygen supplementation should be used liberally, as anoxia develops more quickly in pregnant patients. Maternal oxygen saturation (SaO₂) should be maintained at >95 percent during pregnancy, which is in excess of the oxygen delivery needs of the mother. If SaO₂ consistently falls below 95 percent, an arterial blood gas should be obtained to measure partial pressure of oxygen (PaO₂): Maternal PaO₂ greater than 70 mmHg is desirable to maintain a favorable oxygen diffusion gradient from the maternal to the fetal side of the placenta.

●Consider early intubation – If adequate maternal oxygenation has not been achieved, preoxygenation and early intubation are recommended. Assume a difficult airway as airway edema is more common in pregnant patients and can contribute to difficult intubation.

●Reduce risk of aspiration – Difficulty securing the airway and decreased lower esophageal tone are the primary factors that increase the risk of aspiration. We suggest applying cricoid pressure to prevent aspiration of gastric contents until the airway has been protected with a cuffed endotracheal tube. The value of cricoid pressure has been questioned in nonpregnant individuals because of evidence that it may impair gas exchange and ventilation; however, no randomized trials have assessed the efficacy of cricoid pressure in pregnant patients. Modifying or releasing cricoid pressure should be considered if there are any problems with ventilation or intubation.

If intubation is performed, a nasogastric or orogastric tube should be placed for gastric decompression and mitigation of continued aspiration risk. (See "Initial management of trauma in adults", section on 'Breathing and ventilation'.)

●Remember the diaphragm may be elevated – If a chest tube is placed, the clinician should keep in mind that the diaphragm is elevated in pregnancy. Some experts suggest placing the thoracostomy tube one to two intercostal spaces above the usual landmark of the fifth intercostal space [3,12].

Cervical spine immobilization — Spinal precautions are indicated for all patients who may have a spinal cord injury. If a patient is on a spinal board, it should be removed as soon as is safely possible. (See "Initial management of trauma in adults", section on 'Cervical spine immobilization'.)

Circulation — Circulation is restored/maintained via uterine displacement (if the uterus is at or above the umbilicus), aggressive infusion of crystalloids, and transfusion, when indicated.

●Uterine displacement — If the uterus is at or above the umbilicus, displacing the uterus to the left, off the aortocaval vessels, is critical to maximizing cardiac output and should be done as soon as possible. This is best accomplished by placing the patient on their left side, but if that is not possible then manual displacement or putting a wedge or rolled towel under their right hip or adjusting the platform to achieve at least 30° left lateral tilt is also useful. (See "Sudden cardiac arrest and death in pregnancy", section on 'Avoiding aortocaval compression'.)

●Volume replacement — One or two large bore (eg, 14 or 16 gauge) intravenous lines are placed in patients who may have been seriously injured. Fluid replacement should be aggressive as substantial changes in vital signs may not occur until 15 to 20 percent of total blood volume has been lost (table 2), because of the physiologic hypervolemia of pregnancy [12].

Volume replacement is preferable to vasopressors for blood pressure support since vasopressors can reduce uterine blood flow [13]. Vasopressors (eg, norepinephrine) can be administered to treat persistent hypotension refractory to fluid administration (table 3). (See "Critical illness during pregnancy and the peripartum period", section on 'Vasopressors'.)

●Transfusion — If transfusion is indicated, transfusion protocols and targets are similar to those in nonpregnant individuals, except a fibrinogen level >200 or even 300 mg/dL in actively bleeding patients is desirable because pregnant people have higher baseline fibrinogen levels. A fibrinogen level >200 mg/dL in a pregnant patient is considered the minimum level necessary for adequate coagulation. Fibrinogen levels <100 mg/dL are suggestive of disseminated intravascular coagulation, which can be a complication of placental abruption. (See "Postpartum hemorrhage: Medical and minimally invasive management", section on 'Transfusion targets' and 'Placental abruption' below.)

Typed and cross-matched blood is best, but can require significant time to prepare. Type O RhD-negative blood and can be given to any individual in an emergency, but it is not always available. Transfusion of type O RhD-positive blood to an RhD-negative individual results in substantial risk of alloimmunization, but may be acceptable when transfusion is lifesaving [14]. (See "Initial management of moderate to severe hemorrhage in the adult trauma patient", section on 'Transfusion' and "Pretransfusion testing for red blood cell transfusion", section on 'Emergency release blood for life-threatening anemia or bleeding'.)

●Cardiopulmonary resuscitation — External chest compression is more difficult during pregnancy because of reduced chest compliance [15]. It also may not be effective in the late second and third trimesters because aortocaval compression in the supine position significantly reduces cardiac output, even with uterine displacement [16].

Emptying a uterus that is at or above the umbilicus by performing a cesarean birth increases the effectiveness of cardiopulmonary resuscitation and can save the mother's life, even if the fetus will not benefit because the gestational age is not at a stage of fetal maturity consistent with ex-utero survival [17].

Reviews of perimortem cesarean births suggest optimum newborn and maternal survival are obtained when the cesarean is initiated within four minutes of maternal cardiac arrest and the fetus is delivered within five minutes of unsuccessful resuscitation attempts [16-19]. Fetal survival rates fall to 5 percent after 15 minutes and neonatal survivors are at risk for developing adverse neurologic sequelae [17]. The principle of cesarean birth if maternal resuscitative efforts have not been successful after four minutes (the "five-minute rule") has been adopted by the American Heart Association. (See "Sudden cardiac arrest and death in pregnancy".)

Fetal heart rate evaluation — Measurement of the fetal heart rate is the minimum initial fetal assessment to determine whether the fetus is alive, and if alive, whether it is compromised. The normal fetal heart rate is 110 to 160 beats per minute. It is important to compare the maternal and fetal heart rates to make sure that the fetal heart rate, not the maternal heart rate, is being determined.

If the gestational age is less than 22 or 23 weeks, documentation of the fetal heart rate alone is adequate. At ≥24 weeks, and especially if emergency delivery and neonatal resuscitation would be considered, continuous electronic fetal heart rate monitoring for assessment of both the heart rate and pattern over time is preferable, if feasible. (See 'Fetal assessment' below.)

Neurologic evaluation — A focused neurologic examination is performed after problems related to the airway, breathing, and circulation are addressed, as in nonpregnant patients. (See "Initial management of trauma in adults" and "Initial management of trauma in adults", section on 'Disability and neurologic evaluation'.)

Although seizures may occur as a result of head trauma, assessment for eclampsia should also be done as part of the evaluation of seizures in this population. Eclampsia is a clinical diagnosis typically based upon the occurrence of new-onset generalized tonic-clonic seizures in a patient with preeclampsia (table 4). (See "Eclampsia".)

Diagnostic laboratory tests

●General – Laboratory testing should be performed based upon the clinical scenario and should be limited to those tests that may alter management. (See "Initial management of trauma in adults", section on 'Laboratory tests'.)

●Toxicology – Toxicology screening is appropriate when indicated for forensic purposes or when results might alter acute management. (See "Testing for drugs of abuse (DOAs)", section on 'Indications: When is a DOA screen useful (or not)?'.)

●RhD status – RhD status should be determined. In RhD-negative patients ≥20 weeks of gestation, we obtain a Kleihauer-Betke test (or flow cytometry) to estimate the volume of fetomaternal bleeding and guide anti-D immune globulin dosing. (See 'Fetomaternal bleeding' below and 'Immunization' below.)

Diagnostic imaging — Diagnostic imaging should be performed, as medically appropriate. (See "Initial management of trauma in adults", section on 'Diagnostic studies'.)

●Choose the most appropriate modality for the clinical scenario – When techniques involving ionizing radiation are required, the information obtained nearly always outweighs the radiation risk to the fetus since fetal radiation exposure from diagnostic studies is generally small and without serious fetal effects [20]. The levels of radiation and the risks associated with diagnostic imaging procedures in pregnant patients are discussed in detail separately. (See "Diagnostic imaging in pregnant and lactating patients".)

●Use of ultrasound – Ultrasound, when medically appropriate, is the preferred imaging modality because of its safety in pregnancy. Point-of-care ultrasound is a rapid, limited study that is performed at the bedside for a specific diagnostic or therapeutic obstetric purpose. It is an integral component of trauma management and used primarily to detect free intraperitoneal blood after blunt trauma. The trauma ultrasound examination focuses on dependent intraperitoneal sites where blood is most likely to accumulate: the hepatorenal space (Morison's pouch), the splenorenal recess, and the inferior portion of the peritoneal cavity (including pouch of Douglas). These studies, when combined with evaluation of the pericardium, are referred to as the FAST examination (Focused Assessment with Sonography for Trauma). Extended FAST (eFAST) includes imaging of the anterior lungs bilaterally. (See "Emergency ultrasound in adults with abdominal and thoracic trauma", section on 'Focused Assessment with Sonography for Trauma'.)

Focused Assessment with Sonography for Obstetrics (FASO) is a similar examination for pregnant patients that is limited to intraperitoneal sites, including the uterine cavity [21,22].

●Use of magnetic resonance imaging and computed tomography – Magnetic resonance imaging (MRI) is the preferred diagnostic modality in some cases because it provides better images than ultrasonography, while avoiding the ionizing radiation of computed tomography (CT). If CT or magnetic resonance imaging of the abdomen or pelvis is necessary to evaluate the maternal condition, these studies may identify intrauterine pathology, such as a fetal fracture or placental abruption, as well. (See "Diagnostic imaging in pregnant and lactating patients", section on 'Magnetic resonance imaging' and "Diagnostic imaging in pregnant and lactating patients", section on 'Techniques for minimizing fetal exposure'.)

Role of diagnostic peritoneal lavage — Among patients with abdominal trauma, diagnostic peritoneal lavage has been almost entirely replaced by ultrasound and multidetector helical CT scanning. The procedure may be necessary in some cases, such as in hypotensive patients with equivocal results on FAST examination and multiple potential sources of blood loss, and in resource-poor settings where advanced imaging is unavailable.

If peritoneal lavage is performed in a pregnant patient, an open technique superior to the uterine fundus after placement of a nasogastric tube and bladder catheter is recommended [3,23]. (See "Initial evaluation and management of blunt abdominal trauma in adults" and "Initial evaluation and management of abdominal stab wounds in adults" and "Initial evaluation and management of abdominal gunshot wounds in adults".)

PREGNANCY EVALUATION AND MANAGEMENT AFTER INITIAL MATERNAL STABILIZATION

History — CODE is a mnemonic for the focused history in pregnant trauma patients: Complications of pregnancy, Obstetric history and provider, Dating method and estimated due date, and Event details (eg, leaking amniotic fluid, bleeding, contractions, fetal movement, uterine pain/tenderness) [8].

Physical examination — The goal of the physical examination is to identify maternal and fetal injuries. (See "Initial management of trauma in adults", section on 'Physical examination'.)

Specific considerations in pregnant patients are discussed below.

Determining gestational age — After, or simultaneous with, stabilizing the patient, the gestational age should be determined by history/obstetric records if available, physical examination, and/or point of care ultrasound. This information is crucial when making decisions about management of both the mother and fetus. (See "Prenatal assessment of gestational age, date of delivery, and fetal weight".)

●Physical examination – In singleton pregnancies, the uterus is a pelvic organ for the first 12 weeks of pregnancy. The top of the uterine fundus is palpable above the symphysis pubis at approximately 13 weeks of gestation, halfway to the umbilicus by approximately 16 weeks, at the level of the umbilicus by approximately 20 weeks, halfway between the umbilicus and costal margin at approximately 24 to 28 weeks, and at the costal margin at >34 to 36 weeks (figure 5).

●Fundal height – Once the top of the uterus reaches the umbilicus, the formula for estimating gestational age by physical examination is: Gestational age (weeks) = Distance (cm) from the top of the symphysis pubis to the top of the fundus measured with a measuring tape along the curve of the gravid abdomen. This measurement is called the fundal height.

●Ultrasound – Gestational age can be estimated by fetal biometry (eg, biparietal diameter, femur length) via ultrasound examination. On a point-of-care ultrasound examination, a femur length ≥4 cm is consistent with gestational age where the fetus may survive ex-utero (ie, 4 cm suggests the fetus is between 22 and 24 weeks of gestation [8,9]). (See "Prenatal assessment of gestational age, date of delivery, and fetal weight".)

Abdominal examination after abdominal trauma — Rebound tenderness and guarding secondary to intraabdominal injury may be less prominent than in nonpregnant patients because the gravid uterus lifts and stretches the anterior abdominal wall, potentially impeding contact between areas of inflammation and the parietal peritoneum.

The uterus is examined for:

●Size, which correlates with gestational age (figure 5)

●Tenderness and rigidity, which can be signs of abruption, and

●Intermittent firmness (contractions), which can be a sign of labor

Uterine rupture is not typically detectable on abdominal examination, but the uterus may be tender and fetal parts may be easily palpable.

Detailed discussions of the physical examination after abdominal trauma can be found separately.

●(See "Initial management of trauma in adults", section on 'Abdomen'.)

●(See "Initial evaluation and management of blunt abdominal trauma in adults", section on 'Initial assessment and physical examination'.)

●(See "Initial evaluation and management of abdominal gunshot wounds in adults", section on 'Methods of evaluation'.)

●(See "Initial evaluation and management of abdominal stab wounds in adults", section on 'Methods of evaluation'.)

Vaginal examination — Vaginal examination is performed to assess for bleeding from the vagina or uterus, leakage of amniotic fluid, and cervical change consistent with labor.

Digital vaginal examination should be avoided in pregnancies over 20 weeks of gestation until placenta previa has been excluded by a previous or current ultrasound examination because disturbing the placenta can provoke massive hemorrhage. (See "Placenta previa: Epidemiology, clinical features, diagnosis, morbidity and mortality", section on 'Diagnosis'.)

●Blood – A speculum examination is performed to look for the source of bleeding (vaginal, cervical, or uterine), if present. Before 20 weeks of gestation, uterine bleeding can be a sign of miscarriage (algorithm 2). After 20 weeks of gestation, uterine bleeding is a key finding with placental abruption and placenta previa, and also may occur with labor (table 5). (See "Evaluation and differential diagnosis of vaginal bleeding before 20 weeks of gestation" and "Evaluation and differential diagnosis of vaginal bleeding after 20 weeks of gestation".)

Vaginal bleeding can also be due to vaginal trauma. If a pelvic fracture is known or suspected, take care when examining the vagina to avoid causing more injury from movement of bone fragments.

●Amniotic fluid – The diagnosis of prelabor rupture of membranes is based on visualization of amniotic fluid in the vagina (amniotic fluid is clear or slightly yellow and odorless). In the absence of obvious amniotic fluid pooling in the posterior fornix, ultrasound examination, and sometimes laboratory testing, are used to confirm or exclude the diagnosis, as shown in the algorithm (algorithm 3). (See "Preterm prelabor rupture of membranes: Clinical manifestations and diagnosis", section on 'Diagnostic evaluation and diagnosis' and "Preterm prelabor rupture of membranes: Clinical manifestations and diagnosis".)

●Labor – A digital cervical examination is performed to evaluate for labor in patients with regular uterine contractions or vaginal bleeding (after ultrasound has ruled out a placenta previa). The cervix is normally closed and long (>3 cm thick) before term. A patient over 23 weeks of gestation with cervical dilation and effacement (thinning) and uterine contractions with/without bleeding may be in labor; tocolytic therapy may be indicated. (See "Preterm labor: Clinical findings, diagnostic evaluation, and initial treatment", section on 'Diagnosis' and "Inhibition of acute preterm labor".)

Similar signs and symptoms before 20 weeks suggest inevitable miscarriage. (See "Pregnancy loss (miscarriage): Terminology, risk factors, and etiology" and "Pregnancy loss (miscarriage): Clinical presentations, diagnosis, and initial evaluation".)

Fetal assessment — Fetal status is optimally assessed by continuous fetal heart rate monitoring in pregnancies in which an emergency delivery for fetal indications would be considered. This is usually at ≥24 weeks of gestation, but the lower limit of ex-utero survival is approximately 22 weeks of gestation and some patients may consider intervention and neonatal resuscitation at this age (table 6). This is a complex decision that must be individualized. (See "Periviable birth (limit of viability)".)

In pregnancies at a gestational age below the lower limit of ex-utero survival, documentation of the fetal heart rate alone is generally adequate for fetal assessment. At or above this gestational age, fetal well-being may be formally assessed by one or more of the following:

●Nonstress test (see "Nonstress test and contraction stress test", section on 'Nonstress test')

●Contraction stress test (see "Nonstress test and contraction stress test", section on 'Contraction stress test')

●Biophysical profile (see "Biophysical profile test for antepartum fetal assessment")

Fetal heart rate monitoring — Maternal trauma can compromise the fetus as a result of maternal hypotension or hypoxemia, placental abruption, uterine rupture, or direct fetal injury. We suggest continuous fetal heart rate and uterine contraction monitoring for pregnancies ≥24 weeks of gestation, when feasible.

The fetal heart rate pattern should be monitored by a health care provider experienced in fetal heart rate interpretation. The minimum duration of post-trauma fetal monitoring has not been ascertained; we suggest a minimum of four hours; others have suggested two to six hours [24-27]. Monitoring is extended to a minimum of 24 hours if any signs of abruption are present. (See 'Placental abruption' below.)

The importance of prompt fetal evaluation and appropriate intervention after major maternal trauma was illustrated by a study of 441 pregnant patients presenting to level 1 trauma centers; 91 percent had blunt trauma and 9 percent had penetrating trauma [18]. Major findings of this analysis were:

●Thirty-two patients (7 percent) had an emergency cesarean birth for fetal distress. Fetal and maternal survival were 45 and 72 percent, respectively, in this group.

●No fetus with absent fetal heart tones survived emergency delivery, while 75 percent of those with fetal heart tones and gestational age ≥26 weeks survived.

●Five newborns with heart tones in utero at presentation did not survive; three of these newborn deaths may have resulted from delayed recognition of nonreassuring fetal heart rate patterns. The three mothers had minor injuries (maternal injury severity score <16) and had been under observation for more than 2.5 hours before the cesarean birth was performed for fetal distress.

Role of ultrasound examination

●Determination of gestational age and placental location, assessment of fetal well-being – Whether an obstetric ultrasound should be performed on all pregnant trauma patients is controversial. We believe this decision should be individualized based on factors such as the extent of the trauma, the patient's condition, gestational age, and pregnancy history.

Ultrasound examination of the fetus is useful to determine gestational age and placental position (if not already determined by prior ultrasound) and to evaluate and document fetal status. An abruption is likely if a subchorionic hematoma is observed, but many abruptions are not visualized sonographically. (See 'Placental abruption' below.)

Fetal Focused Assessment with Sonography for Trauma (fetal FAST) consists of assessment of the number of fetuses and their position (eg, cephalic, breech), placental location (previa/no previa; anterior, posterior, or fundal), amniotic fluid volume (low, normal, high), fetal cardiac activity (present/absent; rate normal [110 to 160 beats/minute] or abnormal), and femur length (4 cm suggests gestational age between 22 and 24 weeks of gestation) [8,9].

Ultrasound is always indicated to confirm fetal cardiac activity in the second and third trimesters when fetal heart tones cannot be detected using a Doppler device.

●Assessment for fetal trauma – An anatomic fetal survey is indicated if the clinician believes the fetus may have been injured. For example, blunt or penetrating trauma to the maternal abdomen could result in direct fetal injury, such as fracture or internal bleeding [28,29]. Rarely, a fetal skull fracture with acute intracranial hemorrhage has been reported in patients with pelvic fractures or as a result of deceleration injury after a motor vehicle crash [30,31]. The fetus whose head is deep in the pelvic is probably most at risk for this complication since the uterus, amniotic fluid, and maternal abdominal wall tend to protect an unengaged fetal head from external trauma.

A displaced fetal fracture may be noted on fetal ultrasound examination. Fetal fractures may be detected as an incidental finding on computed tomography (CT) performed for maternal evaluation. If a fetal fracture is noted, evaluation of fetal well-being by nonstress testing and/or biophysical profile and consultation with a neonatologist are advised.

Evaluation and management of obstetric complications — The clinician must also determine whether the patient has any potentially life-threatening obstetric complications. The likelihood of obstetric complications is related, in part, to the gestational age and the severity and type of trauma. The majority of patients who develop adverse obstetric outcomes have symptoms such as contractions, vaginal bleeding, and abdominal pain upon initial presentation [32].

Placental abruption — The uterus changes its shape slightly when subjected to strong acceleration-deceleration forces, such as those experienced during a motor vehicle crash. Since the placenta is not elastic and amniotic fluid is not compressible, uterine distortion related to acceleration-deceleration or direct trauma can result in shear stress at the utero-placental interface, which can lead to placental abruption.

The reported incidence of placental abruption after trauma varies, but is consistently higher than the rate in the general obstetric population, which is 0.4 to 1.3 percent [24,33-36]. In one large series, the frequency of abruption after a motor vehicle crash with severe maternal injury, nonsevere injury, or no injury was 13, 7.4, and 8.5 percent, respectively [36]. However, the rate can be much higher (40 to 66 percent [37]) in patients who sustain severe abdominal trauma.

Significant direct abdominal trauma, abdominal or uterine tenderness, or vaginal bleeding are suggestive of an abruption and warrant fetal and uterine monitoring and laboratory assessment.

●Diagnosis – The diagnosis of abruption is based upon the presence of characteristic clinical features: vaginal bleeding, abdominal pain, contractions, uterine rigidity and tenderness, and possibly a nonreassuring fetal heart rate (FHR) tracing. However, a significant abruption can be asymptomatic or associated with minimal maternal symptoms, including the absence of vaginal bleeding.

Sonographic and laboratory assessments (eg, platelet count and fibrinogen concentration) support the diagnosis if abnormal, but may be normal despite mild to moderate placental separation. Ultrasound examination is of limited usefulness in diagnosing abruption; an abruption is likely if a subchorionic hematoma is observed, but many abruptions are not visualized sonographically [38]. CT and magnetic resonance imaging are never used clinically for evaluation/diagnosis of abruption, but if performed as part of a maternal trauma evaluation, they may show findings consistent with the diagnosis [39]. (See "Acute placental abruption: Pathophysiology, clinical features, diagnosis, and consequences".)

●Fetal monitoring – For pregnancies that have been subjected to more than minor abdominal trauma and have reached the stage of potential neonatal viability, we suggest continuous fetal and uterine monitoring with an external fetal heart rate monitor and tocodynamometer to assess for preterm labor and abruption (algorithm 4). The importance of fetal heart rate and uterine contraction monitoring lie primarily in their negative predictive value for abruption. As an example, one study reported no adverse outcomes directly related to trauma when monitoring was normal and early warning symptoms (bleeding, abdominal pain) were absent (negative predictive value 100 percent) [24]. In contrast, vaginal bleeding, uterine contractions, abnormal fetal heart rate monitoring, and/or abdominal pain or uterine tenderness was not highly predictive of either preterm birth or adverse pregnancy outcome (sensitivity and specificity 52 and 48 percent, respectively). However, identification of a category III tracing and timely delivery can be lifesaving in individual cases [35].

The amount of time the fetus should be monitored is controversial, with recommendations ranging from 4 to 48 hours [24-27]. The rationale for a prolonged period of monitoring is concern about delayed abruption, which has been reported up to six days after a traumatic event [26,40]. However, the risk of a delayed abruption is extremely low. In the study described above [24], repetitive monitoring over several days did not detect any patients whose fetal heart rate tracings evolved from normal to abnormal.

•We suggest discontinuing continuous monitoring after four hours if all of the following criteria are met [24,32,41]:

-Uterine contractions less frequent than 1 in 10 minutes (<6/hour)

-Absence of vaginal bleeding

-Absence of abdominal/uterine pain

-Category 1 fetal heart rate tracing

-Maternal vital signs stable and within acceptable range/baseline

The patient may be discharged if there are no maternal conditions requiring attention.

•We suggest a minimum 24-hour period of monitoring for patients with any of the following:

-Abdominal bruising or other obvious abdominal injury

-Regular contractions (≥1 in 10 minutes [6/hour])

-Vaginal bleeding

-Abnormal fetal heart rate tracing

-Abdominal/uterine pain

-Coagulopathy (eg, low platelets or fibrinogen <200 mg/dL)

These patients should not be discharged until the clinician is reasonably sure that they do not have an abruption or preterm labor.

●Pregnancy management – Pregnancy management is according to usual obstetric protocols for management of abruption. (See "Acute placental abruption: Pathophysiology, clinical features, diagnosis, and consequences" and "Acute placental abruption: Management and long-term prognosis".)

Uterine rupture or penetrating injury — Sharp or blunt abdominal trauma can lead to uterine rupture or penetrating injury [4,42-47]. Signs and symptoms include shock, an abnormal fetal heart rate tracing or fetal death, uterine tenderness, peritoneal irritation, and vaginal bleeding.

Abdominal pain, intraabdominal bleeding, and shock are common after a pelvic fracture and/or rupture of the liver or spleen, and may complicate the diagnosis of uterine rupture or penetrating injury. Imaging studies can help in differential diagnosis, but emergency laparotomy is often required for diagnosis and management. (See "Initial management of trauma in adults", section on 'Secondary evaluation and management' and "Uterine rupture: After previous cesarean birth".)

Fetomaternal bleeding — Fetomaternal bleeding has been reported in 2.6 to 30 percent of pregnant trauma patients [48]. It is more common in patients with an anterior placenta or tender uterus [25,49]. Complications associated with fetomaternal bleeding include fetal anemia, fetal death, and maternal alloimmunization [10].

The occurrence of fetomaternal bleeding can be determined by a Kleihauer-Betke test, which measures the percent of red cells containing fetal hemoglobin in maternal blood. Flow cytometry is an alternative test. (See "Spontaneous massive fetomaternal hemorrhage", section on 'Kleihauer-Betke assay' and "Spontaneous massive fetomaternal hemorrhage", section on 'Flow cytometry'.)

We obtain a Kleihauer-Betke test in RhD-negative pregnant patients ≥20 weeks of gestation who have undergone significant abdominal trauma to determine whether additional doses of anti-D-immune globulin are needed due to a large fetomaternal infusion of blood. (See "RhD alloimmunization: Prevention in pregnant and postpartum patients".)

Although some experts suggest performing a test for fetomaternal bleeding in all pregnant patients with significant abdominal trauma [27], we do not believe this is necessary since the only purpose in D-positive patients would be for diagnosis of life-threatening fetal blood loss, which would be detected sooner by fetal heart rate monitoring. (See "Spontaneous massive fetomaternal hemorrhage", section on 'Clinical presentation'.)

In a series of over 300 pregnant people experiencing minor trauma (motor vehicle accidents, falls, assault), no test including the Kleihauer-Betke performed well in predicting the composite adverse outcome (abruption, preterm delivery, or small for gestational age at delivery) [50]. The only abruption in this series occurred six weeks after the motor vehicle crash.

Antenatal corticosteroids for patients at risk for preterm birth — Patients likely to be at increased risk for preterm birth within the next seven days should receive a course of antenatal corticosteroids (betamethasone or dexamethasone), according to standard guidelines (typically pregnancies from 23 to 34 weeks, but occasionally through 36+6 weeks of gestation). (See "Antenatal corticosteroid therapy for reduction of neonatal respiratory morbidity and mortality from preterm delivery".)

Management of nonobstetric surgery — Management of nonobstetric surgery and anesthesia in pregnant patients is reviewed separately. (See "Anesthesia for nonobstetric surgery during pregnancy".)

Delivery — Emergency cesarean birth is performed in an attempt to:

●Save the fetus in the setting of imminent maternal death or a fetal heart rate tracing predictive of fetal acidosis. Cesarean birth for fetal indications is generally avoided before the fetus has reached a gestational age consistent with ex utero survival. However, deciding upon this gestational age threshold is challenging, as it remains uncertain which extremely preterm infants, particularly those born at 23 and 24 weeks of gestation, have a reasonable chance of survival without severe deficits. (See "Periviable birth (limit of viability)".)

●Save the mother’s life if cardiopulmonary resuscitation has not been effective within four minutes. (See 'Circulation' above.)

Cesarean birth is also performed to provide adequate surgical exposure for management of maternal injuries during laparotomy and when a displaced pelvic fracture precludes vaginal delivery [3].

In pregnant burn patients, delivery is recommended if the pregnancy has reached the third trimester and total body burn surface area is >50 percent [51]. The route of delivery is based on standard obstetric considerations.

Fetal death is not an indication for cesarean birth, except in some cases of placental abruption resulting in maternal coagulopathy and hemodynamic instability. (See "Acute placental abruption: Management and long-term prognosis".)

Immunization

Anti-D immune globulin — RhD-negative pregnant patients with abdominal trauma or vaginal bleeding (who are not already alloimmunized) should receive anti-D immune globulin, per standard protocols. Documentation of a large fetomaternal infusion may require additional doses. (See "RhD alloimmunization: Prevention in pregnant and postpartum patients", section on 'Selective prophylaxis for pregnancy complications associated with fetomaternal bleeding'.)

Tetanus toxoid — Tetanus toxoid is not contraindicated in pregnancy and should be administered as part of wound management, when indicated (table 7). (See "Tetanus-diphtheria toxoid vaccination in adults".)

OUTCOME — Potential consequences of major trauma during pregnancy include:

●Maternal death

●Fetal injury or death

●Pregnancy complications: Miscarriage, abruption, preterm delivery, prelabor rupture of membranes

●Any of the complications of major trauma in the nonpregnant patients

Trauma is a major contributor to maternal mortality and is the leading cause of pregnancy-associated maternal deaths in the United States [52-56]. Severity of injury is the major factor predictive of maternal death [57]. Trauma-related mortality appears to be significantly higher in pregnant people compared with nonpregnant females, but this is controversial because of confounding and selection bias in observational studies [54,58,59].

Factors predictive of poor fetal outcome are maternal hypotension, category II or III fetal heart rate tracing, direct injury to the uterus/fetus, maternal death, and a high maternal Injury Severity Score (ISS, an overall injury score for patients with ) [60-64]. The highest risk of fetal loss (40 to 50 percent) is among patients who sustain life-threatening trauma (eg, with hypovolemic shock, coma, or necessitating emergency laparotomy) [35,61].

Trauma in the first trimester does not usually cause pregnancy loss because the uterus is protected by the maternal pelvis. Exceptions are cases complicated by (1) profound maternal hypotension, which leads to reduced uteroplacental blood flow [61], or (2) serious maternal pelvic injuries (eg, gunshot wounds, pelvic fracture), which can directly injure the fetus, fetal membranes, uterus, placenta, or uterine vessels.

Overall outcome — In a population-based study, one in four pregnant patients admitted to the hospital during the third trimester because of trauma were delivered [33]. Immediate and delayed outcomes after maternal trauma have been evaluated in several large series [33,34,36,54,65-68]. For example:

●One retrospective cohort study used an obstetric database in California to obtain a population-based estimate of pregnancy outcomes in over 10,000 pregnant patients hospitalized due to trauma (table 8 and table 9) [33,34,64]. Motor vehicle accidents were the most common mechanism of injury, followed by falls and assaults.

One-quarter of these patients delivered during the hospitalization for the traumatic event; the remainder were discharged and delivered during a subsequent hospitalization. Patients who delivered remote from their trauma episode still had significantly increased rates of preterm birth, low birth weight, and abruption [33,34]. The authors hypothesized that late morbidity might have resulted from subclinical chronic abruption.

●Another retrospective cohort study evaluated the risk of adverse pregnancy outcome following motor vehicle crashes (n = 582) during pregnancy in Washington State from 1989 to 2001 [36]. The authors compared 84 severely injured (ISS 9), 309 non-severely injured (ISS 1-8), and 189 uninjured (ISS 0) pregnant people with pregnant people who had not been hospitalized for a motor vehicle crash (n = 17,274). Two-thirds of the pregnant people were in the third trimester.

Although 83 percent of the patients were hospitalized and discharged without giving birth, they still bore a high risk of adverse pregnancy outcomes compared with the pregnant people who were not in accidents. Patients with severe injuries were more likely to have had fractures, dislocations, sprains, intracranial injuries, open wounds, and internal injuries, but ISS was a poor predictor of adverse pregnancy outcomes (table 10).

●In a population-based longitudinal cohort study that included over two million children, those with in utero exposure to maternal injury that required emergency department or inpatient care had a modest increase (approximately one additional case per 10,000 child-years) in prevalence of cerebral palsy compared with unexposed children. (See "Cerebral palsy: Epidemiology, etiology, and prevention", section on 'Antenatal infection or injury'.)

MENTAL HEALTH AND COUNSELING — Pregnancy-related complications after trauma can have continued and serious impacts on the injured mother and larger family unit, especially when a poor fetal/neonatal outcome occurs. An early mental health referral should be considered to help provide support.

PREVENTION — Prenatal care should incorporate education about reducing the risk of injury from a motor vehicle crash (correct seat belt use, not turning off airbags) and evaluation for domestic violence, since the majority of maternal trauma is related to these two entities. Maternal bleeding and fetal death rates are reported to be significantly more likely in pregnant people with unbelted or poorly applied seatbelts [69]. Evaluation for misuse of drugs and alcohol and referral for treatment are also indicated, as these are risk factors for trauma in pregnancy and other adverse outcomes.

●(See "Prenatal care: Patient education, health promotion, and safety of commonly used drugs", section on 'Use of seat belts and air bags'.)

●(See "Intimate partner violence: Epidemiology and health consequences", section on 'Pregnancy' and "Intimate partner violence: Diagnosis and screening".)

●(See "Substance use during pregnancy: Screening and prenatal care" and "Alcohol intake and pregnancy".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: General issues of trauma management in adults".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Preventing injuries during pregnancy (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Pregnancy changes – Normal anatomic and physiologic changes related to pregnancy need to be considered when evaluating the status of pregnant trauma victims. (See 'Pregnancy-related changes in physiology' above.)

●Initial management

•ABCs – The initial goal is to assess the maternal airway, breathing, and circulation and establish maternal cardiopulmonary stability, as shown in the algorithm (algorithm 1). (See 'Airway, breathing, and ventilation' above.)

•Keep SaO₂ ≥95 percent – Maternal oxygen saturation (SaO₂) should be maintained at ≥95 percent. Early intubation after preoxygenation is recommended if adequate maternal oxygenation has not been achieved; assume a difficult airway and high risk for gastric aspiration. The diaphragm is elevated in pregnancy so if a thoracostomy tube is needed, some experts suggest placing it one to two intercostal spaces above the usual landmark of the fifth intercostal space. (See 'Airway, breathing, and ventilation' above.)

•Displace the uterus and consider cesarean as a component of cardiopulmonary resuscitation after 20 weeks of gestation – Displacing the uterus approximately 30 degrees to the left, off the vena cava, is critical to maximize effectiveness of cardiopulmonary resuscitation when the uterus is at or above the umbilicus. In some instances, emptying the uterus by performing a cesarean birth is required to save the mother's life. (See 'Circulation' above.)

●Evaluation

•Diagnostic tests/procedures – Any diagnostic test/procedure or treatment required to save the mother's life or treat her critical status should be undertaken, even if potentially disadvantageous to the fetus. Morbidity and mortality in offspring are usually related to the direct and indirect consequences of maternal trauma (eg, hypotension, hypoxemia, placental abruption, preterm birth), but direct fetal injury sometimes occurs. (See 'Initial evaluation and management of major trauma' above and 'Diagnostic imaging' above and 'Role of diagnostic peritoneal lavage' above.)

•Establishing gestational age – In singleton pregnancies, the uterus is a pelvic organ for the first 12 weeks of pregnancy. The top of the uterine fundus is palpable above the symphysis pubis at approximately 13 weeks, halfway to the umbilicus by approximately 16 weeks, at the level of the umbilicus by approximately 20 weeks of gestation, halfway between the umbilicus and costal margin at approximately 24 to 28 weeks, and at the costal margin at >34 to 36 weeks. (See 'Determining gestational age' above.)

•Fetal assessment

-Measurement of the fetal heart rate is the minimum initial fetal assessment to determine whether the fetus is alive, and if alive, whether it is compromised (normal fetal heart rate is 110 to 160 beats per minute). It is important to compare the maternal and fetal heart rates to make sure that the fetal heart rate, not the maternal heart rate, is being monitored. (See 'Fetal heart rate evaluation' above.)

-In pregnancies that have reached ≥24 weeks of gestation, we suggest continuous rather than intermittent fetal and uterine monitoring, when feasible. The earliest gestational age compatible with ex-utero survival is 22 to 23 weeks of gestation, and some patients may consider continuous monitoring with intervention and neonatal resuscitation at this age. This is a complex decision that must be individualized. We monitor patients for at least 4 hours, and up to 24 hours, after even mild abdominal trauma to look for signs of preterm labor and abruption (algorithm 4). (See 'Placental abruption' above.)

-Ultrasound examination of the fetus is indicated if the clinician believes the fetus may have been injured. It is also useful for determining placental position, gestational age, and possibly whether prelabor rupture of membranes or abruption has occurred. (See 'Role of ultrasound examination' above.)

•Pregnancy assessment

-Once catastrophic trauma has been excluded, the clinician should determine whether the patient has any obstetric complications (eg, abruption, uterine rupture, fetomaternal bleeding, preterm labor, premature rupture of membranes). The majority of patients who develop adverse obstetric outcomes have symptoms such as contractions, vaginal bleeding, or abdominal pain upon initial presentation. (See 'Pregnancy evaluation and management after initial maternal stabilization' above.)

-Digital vaginal examination should be avoided in pregnancies over 20 weeks until placenta previa has been excluded by ultrasound examination because disturbing the placenta can provoke massive hemorrhage. Vaginal examination should include assessment for bleeding, rupture of membranes, and labor. (See 'Vaginal examination' above.)

●RhD-negative patients – In RhD-negative pregnant patients, a Kleihauer-Betke test (or flow cytometry) should be obtained in pregnancies ≥20 weeks to quantitate fetomaternal hemorrhage. RhD-negative pregnant patients should be given anti-D immune prophylaxis after major trauma or after minor trauma with vaginal bleeding. (See 'Fetomaternal bleeding' above and 'Immunization' above.)

●Antenatal corticosteroids – Pregnant patients at increased risk for preterm birth in the next seven days should receive a course of antenatal glucocorticoids (betamethasone or dexamethasone), according to standard guidelines (typically pregnancies from 23 to 34 weeks, but occasionally through 36+6 weeks of gestation). (See "Antenatal corticosteroid therapy for reduction of neonatal respiratory morbidity and mortality from preterm delivery".)