Trauma in the Gravid Patient

Published on 22/03/2015 by admin

Last modified 22/04/2025

Print this page

This article have been viewed 1400 times

162 Trauma in the Gravid Patient

Trauma is the most common nonobstetric cause of death in pregnant women, accounting for 46% of maternal deaths.¹ In the United States, 5% to 7% of all pregnancies are complicated by some form of traumatic injury.² The most common mechanisms of blunt trauma are motor vehicle accidents (55%-70%), assaults (11%-21%) and falls (9%-22%).^3,⁴ Penetrating trauma and burns are less common in most communities. The risk of trauma to the fetus increases as pregnancy progresses and the size of the uterus and fetus increases. The most common causes of fetal death are maternal hemorrhagic shock, abruptio placentae, and uterine rupture. A common maternal injury that results in fetal death is pelvic fracture, frequently leading to fetal skull fracture and intracranial injury. However, even relatively minor injuries to the mother can be devastating to the unborn child.⁵

The major causes of death from trauma (i.e., head injury and hemorrhage) are similar in gravid and nongravid patients. Patterns of injury are generally the same, based upon mechanism of injury. Hepatic and splenic injuries remain common, though gastrointestinal injuries are less common as the pregnancy progresses and the uterus enlarges.⁶

The outcome from trauma for the mother and fetus is dependent upon multiple factors, including gestational age of the fetus and the mechanism and severity of injury. The largest contributor to fetal mortality is gestational age less than 28 weeks.⁵ Scorpio et al.⁷ found in gravid victims of mostly blunt trauma (80% motor vehicle crashes) that injury severity score and admission serum bicarbonate level were the only independent factors that predicted fetal demise. The serum bicarbonate or base deficit may be important markers of occult hypoperfusion in trauma victims, though serum bicarbonate is normally decreased late in pregnancy. El Kady et al.⁵ and Schiff et al.⁸ reported that while the actual injury severity score was not predictive of fetal outcomes, maternal and fetal mortality were highest with internal injuries to the thorax, abdomen, and pelvis. The critical factor for the fetus is the extent to which trauma disrupts normal uterine and fetal physiology. Fetal demise occurs in up to 80% of gravid patients who develop hemorrhagic shock. In addition, however, even minor injuries to the mother can result in abruptio placentae or fetal demise.⁵ In one study of interpersonal violence as a cause of trauma in pregnancy, 5 of 8 women with fetal losses had no apparent physical injury.⁹

Any female patient of child-bearing potential could be pregnant at the time of injury. Screening (beta-human choriogonadotropin) should therefore be routine during the initial assessment of the patient. Recognition that a “second” patient is present is essential for the care of both mother and fetus. Optimal management of the pregnant trauma victim is the best way to optimize outcome for the fetus: “save the mother, save the fetus.” To manage the gravid patient, the traumatologist or intensivist must have an understanding of fetal and maternal physiology, as well as the specific complications of trauma that are unique to these patients. Early obstetric consultation should be obtained. If delivery of a viable fetus is imminent, neonatology consultation may also be needed.

Fetal Physiology

During the first week after conception, the conceptus has not yet implanted in the uterus, making it relatively resistant to injury. Soon thereafter, the blastocyst begins implantation and the placenta begins to develop. The embryo attaches to the uterus via anchoring villi. The placenta is not as elastic as the myometrium, potentially leading to shear stresses and disruption of these villi (particularly if intraamniotic fluid pressure is increased) when force is applied to the uterus. The resulting abruptio placentae rapidly leads to fetal hypoxemia, acidosis, and death.

On the positive side, amniotic fluid is a cushion for the fetus, but the fetus may still suffer injury as a result of rapid compression, deceleration, or contrecoup injury. Late in pregnancy, however, the head of the fetus is typically in the pelvis. Pelvic fractures may lead to fetal skull fracture and brain injury.⁴

Adequate oxygen delivery to the fetus is critical during pregnancy. Blood flow to the uterus decreases proportionally as maternal systemic blood pressure decreases. In addition, as the mother becomes hypovolemic, peripheral vasoconstriction can further decrease uterine circulation. The placenta is exquisitely sensitive to catecholamines. The ability of the fetus to withstand changes in uterine blood flow and/or oxygenation is variable. The fetus can redistribute blood flow to the most vulnerable organs, the brain and heart, but this response (the “diving reflex”) is limited. Decreased placental blood flow quickly leads to fetal distress.

Anatomic and Physiologic Changes Associated with Pregnancy

The gravid patient undergoes a multitude of anatomic and physiologic changes to accommodate the developing fetus. Theses changes have a significant impact upon anatomic injury patterns and the response to injury.

From a respiratory standpoint, maternal tidal volume increases by as much as 40%, causing respiratory alkalosis. Renal compensation maintains a normal arterial pH. The diaphragms are elevated, decreasing functional residual capacity and risking intraabdominal placement of chest tubes. The gravid patient has little respiratory reserve and desaturates quickly.

From a cardiovascular standpoint, heart rate increases by 15 to 20 beats per minute by the third trimester. During the second trimester, both systolic and diastolic blood pressure decrease by about 15 mm Hg, then increase to normal levels during the third trimester. By the 10th week of pregnancy, cardiac output increases by 1 to 1.5 L/min due to increased plasma volume and decreased peripheral resistance.

Maternal blood volume increases by nearly 50% by 28 weeks. Red cell mass does not increase proportionally, leading to the “anemia of pregnancy.” Normal hematocrit late in pregnancy is 31% to 35%. A mild leukocytosis (up to 18,000 cells/mL) occurs during the second trimester. Coagulation factors and fibrinogen levels increase while plasminogen activator levels decrease during pregnancy, leading to an increased risk of thromboembolism. Trauma to the gravid uterus can lead to release of thromboplastic factors (e.g., amniotic fluid) which can cause disseminated intravascular coagulation (DIC). Serum albumin levels decrease to 2.2 to 2.8 gm/dL.

Decreased gastric motility and cephalad displacement of the abdominal contents predispose women to gastroesophageal reflux and aspiration. Gallbladder function is also impaired, increasing risk of stone formation.

The abdominal examination of gravid women is complicated by cephalad displacement of the abdominal contents by the enlarging uterus. The urinary bladder is displaced upward out of the pelvis, and the ureters become dilated after the 10th week of gestation.

During pregnancy, the uterus increases in size from 70 to 1100 g, taking on an intraabdominal position after 12 weeks, increasing risk of direct trauma. At 20 weeks, the fundus reaches the umbilicus. By 34 to 36 weeks, it reaches the costal margin. Uterine blood flow increases to 10 times normal. One of the most important consequences of the anatomic changes during the latter half of pregnancy is that the uterus can occlude the inferior vena cava when the patient is in the supine position (supine hypotension syndrome), leading to hypotension from decreased venous return. Positioning the patient with the right side of the torso elevated can increase cardiac output by up to 25%. The pelvis of the gravid female has relaxed ligaments, causing gait instability and risk of falls. In addition, venous engorgement in the pelvis increases risk of severe hemorrhage.

From an endocrine standpoint, the hormones of pregnancy (placental lactogen, progesterone, estrogen, parathormone, and calcitonin) lead to insulin resistance and diabetes of pregnancy, decreased lower esophageal sphincter pressure, decreased gastric emptying, and increased calcium absorption. The pituitary gland is increased in size by 135% with increased blood flow demands. Hemorrhagic shock can lead to necrosis of the gland and pituitary insufficiency (Sheehan’s syndrome). Preeclampsia (triad of hypertension, proteinuria, and peripheral edema) can increase risk of intracranial hemorrhage or seizures. Subsequent neurologic findings may mimic head injury.

Initial Assessment and Resuscitation

Optimal care of the mother will maximize the chances for survival of the fetus. Resuscitation of the gravid patient should follow guidelines for the nongravid patient. Given the exquisite sensitivity of the placenta and fetus to hypoperfusion and hypoxemia, supplemental oxygen and intravenous fluids should be administered early, even before extrication if possible, particularly since the latter may be delayed by anatomic factors. There is no indication for fetal assessment in the field. Use of the pneumatic antishock garment for stabilization of fractures or control of hemorrhage is contraindicated because the resulting increase in intraabdominal pressure can further decrease venous return in the gravid patient.

Prehospital protocols and interhospital transfer arrangements must account for management of a pregnant trauma victim. The optimal receiving facility should have obstetric and neonatology consultants available, even if it is not the closest trauma center.

The airway of the gravid patient is at risk because of the tendency toward gastroesophageal reflux and aspiration. In addition, the vocal cords are frequently edematous. Ventilation of the gravid patient late in pregnancy may be impeded by the enlarged uterus and cephalad positioning of the abdominal contents. Functional residual capacity may be significantly reduced, leading to more rapid decompensation, particularly with chest trauma.

Because of the increased blood volume late in pregnancy, the mother may not show signs of hypovolemia, given the same blood loss (up to 1500 mL) as a nongravid patient. Uterine perfusion, however, may still be compromised. Uterine blood flow may decrease by up to 30% before the mother demonstrates clinical signs of shock. Aggressive volume replacement is necessary to assure adequate uterine blood flow. Blood transfusions should be administered per standard guidelines, but the mother’s Rh-antigen status must be considered. If it is unknown, Rh-negative blood should be administered. Invasive hemodynamic monitoring should be considered early during resuscitation to assure adequate volume resuscitation.

To prevent the supine hypotensive syndrome, beyond 20 weeks of gestation, patients should be placed in the left lateral decubitus position to relieve the pressure of the uterus from the inferior vena cava. The uterus can also be manually displaced to the left. If the patient is immobilized on a long board before spinal injury is ruled out, the entire board can be tilted 15 degrees with a wedge. Vasopressors, which are very rarely indicated in trauma patients, should be avoided unless absolutely necessary because of the risk of decreasing uterine blood flow.

In addition to the standard initial assessment, evaluation of the gravid trauma patient should include a focused history and physical examination related to the pregnancy. The obstetric history should include the date of last menstrual period, expected date of delivery, date of first fetal movement, and status of current and previous pregnancies. The physical examination should include measurement of fundal height. Fetal age can be estimated as 1 week for each centimeter fundal height above the symphysis pubis. The abdominal examination should assess uterine tenderness and consistency, presence or absence of contractions, and determination of fetal position and movement. Pelvic examination should evaluate the presence of blood or amniotic fluid, cervical effacement, dilation, and fetal station. Amniotic fluid can be identified using Nitrazine paper to detect pH. A pH of 7 to 7.5 suggests the presence of amniotic fluid. Vaginal bleeding may indicate abruptio placentae. The Kleihauer-Betke (KB) test is used after maternal injury to identify fetal blood in the maternal circulation. When fetomaternal hemorrhage is present, additional doses of Rho(D) immunoglobulin may be given.¹⁰ Examination of the fetus beyond 20 weeks should include auscultation of fetal heart tones. Normal range is 120 to 160 bpm.

Standard laboratory tests should be obtained, including a pregnancy test. In addition, coagulation studies, including fibrinogen level, should be checked since DIC can occur during pregnancy from release of thromboplastic substances from abruptio placentae or amniotic fluid embolism. Treatment may include urgent delivery of the fetus and blood component therapy.

Radiographic Studies

Evaluation of the trauma victim invariably involves multiple radiographic studies. Concern for fetal radiation exposure should not prevent clinicians from obtaining studies needed for optimal care of the mother, though duplication of radiographic studies should be avoided.

The effect of radiation during development of the embryo and fetus is dependent upon dose and timing. Previously it was felt that any radiation very early in development of the embryo would be injurious. More recent findings, however, suggest that this is not the case, and that the fetus is most sensitive to the effects at 8 to 15 weeks when brain development is maximum.¹¹ Radiation can be teratogenic and can retard growth or cause postnatal neoplasia, but the risk is low after 15 weeks gestation when organogenesis is nearly complete.

Mann et al.¹² stratified risk of adverse effects of radiation for diagnostic studies. Less than 10 mGy (equivalent to 1 rad) was considered low risk, 10 to 250 mGy as intermediate risk, and over 250 mGy as high risk. In general, a single exposure for a plain radiograph results in an exposure of 2 mGy, whereas computed tomography (CT) may lead to an exposure of 5 mGy per slice and fluoroscopy as much as 10 mGy per minute. Exposure in the low category carries minimal risk of mutations. Though the risk of childhood cancers may be increased, the resultant risk remains less than 0.1%. In the intermediate category, specifically above 150 mGy, teratogenic effects may be seen. In the high category, the risk of teratogenic or carcinogenic effects increases significantly, perhaps to 2% to 3% above that of the normal population.

The greatest exposure to the fetus occurs when it is in the direct beam of the radiograph. To minimize exposure, the lower abdomen and pelvis of the gravid patient can be shielded with lead. Typical radiation exposure for the shielded fetus during a maternal chest radiograph is less than 0.01 mGy. In contrast, a pelvic CT scan for which the fetus cannot be shielded is 20 to 80 mGy.¹³ The exact efficacy of shielding with lead during these examinations is unclear.

Blunt Trauma

Radiographic evaluation of the gravid blunt trauma victim should begin with the standard chest and pelvis radiographs. Beyond this, additional studies should be chosen based on the findings on physical examination, potential benefit to the mother, and risk to the fetus. If there are acceptable choices for evaluation, the one that entails the least radiation exposure to the fetus should be utilized. For example, one could use ultrasound or diagnostic peritoneal lavage (DPL) instead of CT to evaluate the abdomen, although the latter should be performed if necessary. The focused abdominal sonogram for trauma (FAST) should be utilized in the gravid patient just as in other trauma patients, except that superior displacement of abdominal organs by the uterus should be considered for probe placement. DPL should be performed above the umbilicus. On the other hand, if given a choice between radiographic embolization of bleeding from a splenic injury versus laparotomy, the laparotomy may be the more appropriate choice. Weighing the risks and benefits of radiographic studies is complex. Decisions should be made by the most senior physician involved in the care of the patient.

Penetrating Trauma

As gestation progresses, the uterus becomes the most likely organ to be injured. The uterus and amniotic fluid can slow the velocity of missiles, decreasing potential injury to the mother, though not protecting the fetus very well. Approximately 60% to 70% of gunshot wounds to the pregnant abdomen result in fetal injury, with a subsequent fetal mortality of subsequently 40% to 65%.¹⁴ Penetrating trauma to the upper abdomen frequently involves multiple loops of bowel, which are compressed above the enlarged uterus, leading to complex injuries. Management of gravid patients with entry wounds below the fundus of the uterus is controversial. Although immediate laparotomy is indicated for most nongravid victims of penetrating abdominal trauma, particularly gunshot wounds, this is not the universal standard in the gravid patient. Nonoperative management can be employed if maternal vital signs and fetal heart rate tracings remain normal, suggesting no evidence of maternal or fetal compromise or intraabdominal hemorrhage.² Radiographic determination of bullet location may be helpful. Intrauterine bullets may be observed. If laparotomy is performed, all bowel should be carefully explored and wounds repaired. Wounds to the uterus should also be closed. Antibiotics for gram-positive cocci and clostridia should be given as soon as possible.¹⁵ Also, tetanus prophylaxis is safe in pregnancy, and the indications for use in penetrating trauma patients are the same for pregnant and nonpregnant patients.

Operative Procedures

Operative intervention in the gravid patient should be based upon standard indications for nongravid patients. There is no reason for delay. Anesthetic management using inhalational agents and neuromuscular blockade is considered safe. Local anesthetics should be used with caution, as they may cross the placenta. The uterus should be handled carefully without using excessive traction in order to protect fetal perfusion via the uterine arteries. In damage-control laparotomies, the abdomen can be left open in both gravid and nongravid patients who are predisposed to the development of abdominal compartment syndrome.

Medications

Medications frequently have different effects on the gravid patient and the fetus compared to normal, nongravid females. Table 162-1 lists commonly used medications and the current recommendations regarding their use during pregnancy. Because not all medications, particularly newer ones, have been extensively tested in pregnant women, all medications should be administered with some caution in the gravid patient.

TABLE 162-1 Medications and Pregnancy

Monitoring

Monitoring of fetal cardiac activity and maternal uterine activity (cardiotocographic monitoring) is indicated if the fetus has reached the point of viability if delivered. Since this complication can occur shortly after injury, monitoring should begin as soon as possible. Almost all patients who develop abruptio placentae have frequent uterine contractions (>8 per hour) during the first few hours after trauma; this is the most frequent finding with abruption. Continuous monitoring of the fetal heart beat can detect fetal distress quickly. Normal fetal heart rate is 120 to 160 beats/min. Signs of fetal distress include an abnormal baseline fetal heart rate, absence of normal accelerations and beat-to-beat variability, and repetitive decelerations. The duration of monitoring is somewhat controversial. Although delayed abruption has been reported,^16,¹⁷ these patients were not monitored immediately after injury. Monitoring is clearly recommended for gravid patients with frequent uterine activity (>5 contractions per hour), abdominal or uterine tenderness, vaginal bleeding, rupture of amniotic membranes, or hypotension. Some have suggested that patients who are asymptomatic should be observed for at least 4 to 6 hours because approximately 80% of abruptions will occur during this interval.¹⁸ Fetal monitoring throughout a 24-hour observation admission may be performed, though the utility of continuous fetal monitoring beyond this point is limited.

The utility of ultrasound of the pelvis during initial management of the gravid patient is less clear. It is less accurate than cardiotocographic monitoring for detecting abruptio placentae or fetal distress, with a sensitivity of less than 50%.¹⁹ When a CT scan is performed on a pregnant trauma patient to look for abdominal or pelvic injuries, Manriquez et al. found that placental injuries could be diagnosed with 86% sensitivity and 98% specificity.²⁰ On the other hand, ultrasound can also establish gestational age, determine fetal well-being if the cardiac monitoring is equivocal, verify presence or absence of fetal cardiac activity, and estimate the volume of amniotic fluid if rupture of membranes is suspected. Early obstetric consultation is critical so that if fetal distress occurs, rapid intervention, including Cesarean section, can proceed. Neonatology consultation may also be indicated.

Specific Complications of Pregnancy

Fetomaternal Hemorrhage

Following trauma, fetal blood can cross the placenta and enter the maternal circulation. This occurs in 10% to 30% of pregnant trauma patients.¹⁵ The volume can be approximated by measuring the ratio of fetal to maternal red blood cells in the maternal circulation with the Kleihauer-Betke (KB) test. Complications include Rh sensitization of the mother, neonatal anemia, cardiac arrhythmias in the fetus, and fetal death from exsanguination. Maternal sensitization may be prevented by administration of Rho(D) immune globulin. Because the KB test may not be sensitive enough to detect the amount of fetal hemoglobin that can sensitize the mother, administration of Rho(D) immune globulin is indicated in almost all Rh-negative mothers unless the injury is relatively minor and far removed from the uterus. In addition, positive KB tests should be repeated in 24 to 48 hours to follow the progression of fetomaternal hemorrhage.¹⁸

Abruptio Placentae

The most common cause of fetal death with maternal survival is abruptio placentae, which can occur after minor trauma, particularly late in pregnancy. Patients present with abdominal pain, vaginal bleeding, premature rupture of membranes with leakage of amniotic fluid, uterine tenderness and rigidity, expanding fundal height, and maternal shock. Fetal distress may rapidly follow. If the fetus is viable, Cesarean section may be necessary.

Amniotic Fluid Embolism

Trauma to the uterus can result in embolization of amniotic fluid into the maternal circulation, causing a consumptive coagulopathy. Treatment consists of delivery of the fetus and transfusion of platelets and clotting factors, including fibrinogen.

Premature Labor

Premature uterine contractions associated with cervical dilatation and effacement (i.e., signs of premature labor) are common after trauma. A positive KB test may be one of the most predictive factors for premature labor.¹⁸ Fortunately, premature labor is usually self-limited, but some patients require tocolytics. Evidence of abruptio placentae is a contraindication to tocolytic therapy.

Uterine Rupture

Direct trauma to the uterus can result in rupture, which almost always leads to fetal death and significantly increases risk of maternal death (usually from concomitant injuries). Typical findings include abdominal pain and tenderness with peritoneal signs. If the fetus is out of the uterus, it may lie in a transverse or oblique position. Fetal body parts may be palpable, although the uterine fundus may not be. Fortunately, uterine rupture only occurs in the most seriously injured patients and remains rare.

Fetal Demise

If fetal demise occurs, labor usually begins within 48 hours. If it does not, induction or Cesarean delivery are indicated, as well as observation for evidence of DIC.

Cesarean Section

Depending upon the potential for viability based on fetal age, the indications for urgent Cesarean section in gravid trauma victims include fetal distress, abruptio placentae, uterine rupture, and fetal malposition with premature labor. Possible maternal factors include inadequate exposure for control of other injuries and DIC.

Cardiac Arrest

During resuscitation, standard algorithms should be applied initially. The uterus can be manually displaced toward the left side, off the inferior vena cava. Optimizing cardiac output and perfusion of the uterus via left thoracotomy and open cardiac massage along with emergency Cesarean section should be considered. By the time the mother has suffered a cardiac arrest from trauma, the fetus has already suffered severe hypoxia. Cesarean delivery may be indicated if the fetus is thought to be viable and the procedure can be performed within 5 minutes of the loss of pulse in the mother.² If fetal vital signs persist, delivery may be performed after 5 minutes, though survival becomes less likely as time passes. Cardiopulmonary resuscitation must be continued until delivery is accomplished. Delivery has also been reported to allow successful maternal resuscitation. Decision to proceed with postmortem delivery must be made quickly by the traumatologist and obstetrician; hemostasis and antisepsis become secondary issues. Perimortem Cesarean delivery is performed via a midline incision through all layers of the uterus. Neonatologists must be available.

Maternal Head Trauma

Continuing life support in gravid patients with severe head trauma but viable fetuses is controversial. Brain-dead patients have been sustained long enough for safe delivery of the fetus.²¹ Consultation with obstetricians and ethicists is essential.

Prevention

Risk factors for maternal trauma include age younger than 25 years, African American or Hispanic race, low socioeconomic status, use of illicit drugs or alcohol, noncompliance with proper seatbelt use, and domestic violence.

Ikossi et al. revealed that 19.6% of pregnancy-related trauma was associated with illicit drug use, and 12.9% involved alcohol.²² Education about the risks of drug and alcohol use during pregnancy is needed for all women, especially those in high-risk situations.

Proper seat belt use improves survival after motor vehicle crashes by preventing ejection from the vehicle. According to the National Highway Traffic Safety Administration, the lap belt should cross over the bony pelvis as low as possible under the pregnant belly, with the shoulder belt between the breasts and away from the neck.¹⁵ The shoulder belt can help dissipate the force of deceleration and prevent severe flexion at the waist. Although standard seat belt and shoulder harnesses were not specifically designed for the gravid patient, it is estimated that up to 50% of fetal losses following motor vehicle collisions could be prevented if seat belts are used correctly.²³

Violent trauma is a major cause of maternal and fetal death that is most likely quite under-reported.^15,¹⁸ Approximately 17% to 32% of gravid trauma patients have reported being injured by another person, and up to 60% of these are repeated cases of domestic violence.³ Factors that should raise concern about domestic violence include injuries inconsistent with the history, diminished self-image, depression, history of self-abuse or suicide attempts, substance abuse, self-blame for injuries, and frequent visits. One should also be concerned if the partner insists upon being present for the examination and monopolizes the conversation. Physicians have a responsibility to identify these injuries and document them with the appropriate authorities.