Susan M. Lanni
History of present illness
A 25-year-old gravida 2, para 1-0-0-1 woman at 28 weeks’
gestation was traveling at posted speed as the unrestrained driver in a car on a major multilane interstate. While driving, her attention waned, and she veered into the adjacent travel lane. She was struck from behind causing her car to spin out of control. Ultimately, her vehicle was hit by two more vehicles traveling in the same direction, and then struck head on by a third car causing her to be ejected from the vehicle. A witness called for emergency medical assistance, which was on scene withinfive minutes of the crash. There was loss of conscious- ness. A cervical collar was placed, and her vital signs were rapidly assessed.
Injury assessment/physical examination in the field
General appearance:Suspected head injury based on mechanism of injury, multiple deep and nonhemostatic lacerations and abrasions of the face and arms, legs and chest, a chest contusion extending from T4 level to
umbilicus, contusions of the abdomen. Compound fracture of left femur, suspected crush injury of pelvis
Vital signs:
Pulse: 135 beats/min
Blood pressure: 167/77 mmHg
Respiratory rate: 45 breaths/min, shallow, labored Oxygen saturation: 96% on 100% FiO2
Fetal heart rate: 170 beats/min Abdomen:Uterine tetany
Ancillary evaluation:Pants soaked and bloody
Course of events
Her respiratory status deteriorated, and she was intubated in the field, as simultaneously intravenous access was obtained.
She was transported to a Level 1 trauma facility. Heavy vaginal bleeding was encountered, and blood filled the endotracheal (ET) tube. In the trauma bay, the trauma team and the obstet- ric team quickly assessed her status, while the neonatal team stood by. The patient was on a backboard tilted to the left, and a FAST (Focused Assessment with Sonography for Trauma) scan revealed significant blood in the abdomen; the fetal heart rate was noted to be 40 beats/min. Maternal asystole was encountered, and chest compressions were initiated, without
regaining a maternal pulse afterfive minutes. Despite aggres- sive volume resuscitation with O-negative blood and intraven- ousfluids, maternal status did not improve. The obstetric team performed emergent Cesarean delivery in the trauma bay via a midline vertical incision; delivery of the cephalic-presenting fetus was 45 seconds after skin incision was made. The neonate was noted to have absent heart rate, poor tone, pale color, and no spontaneous respiratory effort. In addition, the pupils were dilated without reactivity and a depressed parietal bone skull fracture was noted. Resuscitative efforts for the neonate were halted. Meanwhile, the obstetric team repaired the hysterotomy as the trauma team continued resuscitative efforts. Despite an electrical rhythm being obtained, a pulse was never generated. Resuscitative efforts were discontinued at this time.
What is the mechanism of injury?
The mechanism of injury is an unrestrained driver sustaining high speed blunt trauma, causing massive intra-abdominal hemorrhage, acute traumatic membrane rupture and placental abruption, as well as suspected pulmonary hemorrhage from blunt chest trauma. The cephalic-presenting fetus sustained a skull fracture due to the blunt force applied to the maternal pelvis.
Trauma in pregnancy
When all types of trauma are considered, it is suspected that 1 in 12 pregnancies encounter trauma. Certainly, vehicular trauma is but one type, but is the largest contributor to pre- term labor and birth, membrane rupture, placental abruption, Cesarean delivery, and intrauterine/neonatal demise resulting from trauma. Pregnancy does not impact severity, mortality, or morbidity of trauma but certainly affects the pattern of injury and the patient’s care. Vehicular crashes account for the highest degree of both maternal and fetal/neonatal mortal- ity among all causes of trauma. Outcome of vehicular trauma is affected by seatbelt use; in 2008, 85% of adults surveyed used seatbelts. Seat belt use reduced the likelihood of serious injury in a crash by approximately 45–50% [1]. This is, however, countered by fewer pregnant women at advanced gestational ages wearing seatbelts than by pregnant women below 20 weeks’gestation.
It is estimated that less than 50% of patients are counseled about proper seatbelt use in pregnancy [2]. Seatbelts, both the lap belt and shoulder strap should be used. The lap belt
Acute Care and Emergency Gynecology, ed. David Chelmow, Christine R. Isaacs and Ashley Carroll. Published by Cambridge University Press.
© Cambridge University Press 2015.
portion should be placed below the pregnant belly and the shoulder strap between the breasts but then lateral to the fundus of the uterus (Fig. 57.1). Airbags and supplemental restraint systems should also be used during pregnancy.
Although originally airbags were designed to protect 185-lb male drivers of at least 68 inches at high speeds, as of 2012, all supplemental restraints have been modified to provide safety to women, and in crashes of all speeds [3]. The National Highway Traffic Safety Administration (NHTSA) recom- mends that the sternum of a pregnant woman be at least 10 inches from the steering wheel or dashboard, and the seat should be adjusted as the abdomen grows.
The evaluation of a pregnant trauma patient is similar to any nonpregnant patient, and begins with thefield technicians and paramedics. The ABCs of trauma management apply, as the maternal condition is considered primarily above the fetal condition in all situations and irrespective of gestational age.
Physiologic changes associated with pregnancy need to be taken into account to ensure proper care. The increased vascu- lar volume makes the diagnosis of hypovolemia less evident.
Lateral displacement of the gravid uterus offthe vena cava will ensure adequate venous return and promote maintenance of cardiac output, which is critical where significant intra- abdominal hemorrhage is suspected. Lateral displacement of
the uterus can be accomplished by manually pushing the uterus to the side, or by the use of a wedge under the back- board. In a conscious, stable patient, maintaining the left lateral tilt or decubitus position is sufficient.
Maternal oxygen saturation should be maintained greater than 90% at minimum. At this saturation, the maternalPO2is approximately 60 mmHg, which is sufficient to maintain a gradi- ent favoring the delivery of oxygen to the fetus. If saturations fall below 90%, use of supplemental oxygen by nasal cannula, and nonrebreather masks, or ET intubation may be warranted. Intub- ation is often required for airway protection in the unconscious patient. Aspiration risk is greater when ET intubation is used for the pregnant patient compared to the nonpregnant patient, due to relaxation of the lower esophageal sphincter and altered gas- trointestinal motility associated with normal pregnancy physi- ology. Airway edema may be present in normal pregnancy.
Intravenous access should be obtained in thefield, with two 14–18 gauge intravenous catheters. Volume resuscitation using isotonic solutions (normal saline or lactated Ringer’s solution) is given in a ratio of 3 : 1 to blood loss. Estimation of blood loss is difficult in a pregnant trauma patient; a 25% loss of blood volume is generally needed to cause a change in maternal vital signs. It is prudent, therefore, to aggressively resuscitate the pregnant trauma patient when hemorrhage is observed or expected. lactated Ringer’s solution may have pro-inflammatory effects, and may contribute to multiorgan failure and acute respiratory distress syndrome (ARDS).
Initial hospital care includes injury assessment, maternal vital signs, and evaluation of gestational age and fetal status, which becomes the role of the obstetrician. These factors may affect decisions regarding the care of the mother. Survey of injuries in the pregnant patient should employ all modalities required for adequate assessment, including radiologic studies. CT imaging of the abdomen and pelvis expose the fetus to approximately 3.5 rads; 20–50 rads is required before damage to the fetus should be suspected [4]. Focused Abdominal Sonography for Trauma (FAST) has largely replaced diagnostic peritoneal lavage (DPL) for diagnosis of intra-abdominal bleeding. DPL is disadvanta- geous in pregnancies of approximately 20 weeks and beyond due to the location of the fundus under the site of entry of the lavage catheter. FAST has the advantage of the immediate ability to
“pass the transducer”to the obstetric team for evaluation of the fetus. FAST has high sensitivity (90%) in thefirst trimester, but low specificity (89%) compared to other trimesters. Negative predictive values approach 100% across trimesters [5].
Placental abruption is not easily diagnosed by ultrasound, but abnormal fetal heart rate patterns especially tachycardia, loss of variability, and late decelerations are observed in the setting of abruption. Uterine contractions greater than 1 every 10 minutes are associated with nearly a 20% rate of placental abruption [6]. Fetomaternal hemorrhage occurs in 10–30% of pregnant trauma patients [7]. In the case of an Rh-negative unsensitized mother, Rh immune globulin should be adminis- tered in the standard dose, as 90% of fetomaternal hemorrhages are less than 30 mL in volume [8].
Fig. 57.1 Proper seat belt placement in a 36-weeks pregnant patient.
(Photograph courtesy of Susan Lanni, MD; by permission of patient.)
Case 57: A high-speed motor vehicle accident during pregnancy
In the above case, the gestational age favors the need to monitor the fetus; however, in light of maternal asystole, monitoring is obviated. Additionally, suspicion of a crush injury to the pelvis predicts poor fetal outcome. Decision to perform perimortem Cesarean delivery should be based on potential survival for the neonate, but may improve survival for the mother also. It is generally performed in the setting of imminent maternal death, or after four minutes of properly performed CPR, as seen in the case above. Neonatal outcomes for fetuses of a viable gestational age (typically 23–24 weeks and above, but are dependent on resources available at the individual hospital) are best when perimortem Cesarean is performed within 5 minutes of maternal asystole [9].
It is estimated that intrauterine death from trauma affects 2.3 per 100 000 live births. Fetal head trauma is almost univer- sally fatal, and when the fetus is in cephalic presentation, the fetal head is cushioned by proportionally less myometrium, allowing the maternal pelvis to contribute to this type of injury. Third trimester is the most common trimester for trauma-related injuries to affect the fetus. Factors that inde- pendently portend poor fetal outcomes include maternal loss of consciousness and pelvic injury [10].
Key teaching points
All pregnant women should be instructed on proper seatbelt use.
Evaluation of the pregnant trauma patient should always start with the ABCs of life support.
Lateral displacement of the gravid uterus offof the vena cava will promote maximal venous return and facilitate maintenance of maternal cardiac output.
All members of the teams caring for the pregnant trauma patient should be apprised of normal pregnancy
physiologic changes.
The mother’s status always takes precedence over the fetal status in the situation of resuscitation.
If efforts to resuscitate the mother can be improved by uterine evacuation, then delivery should be considered.
Imaging studies should not be deferred due to risk of radiation exposure to the fetus.
Perimortem Cesarean delivery for gestations above 24 weeks is ideally performed within 5 minutes of initiation of CPR for maternal cardiac arrest.
References
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Passenger Car Front Seat Occupant Protection. Washington, DC, US Department of Transportation, National Highway Traffic Safety Administration, 1984. Publication # DOT-HS-806-572. Available athttp://
www-nrd.nhtsa.dot.gov/pubs/806572.
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