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Trauma Considerations for the Pregnant Patient

Emergency Medicine
Surgery
Military Medicine
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Introduction:

Trauma affects up to 10% of pregnancies and is the leading cause of nonobstetric maternal death. Major trauma during pregnancy is associated with up to 7% mortality of the pregnant person and 60-80% mortality of the fetus [1].
Fetal outcomes associated with maternal trauma include preterm delivery, low birth weight and fetal demise. Effective clinical management requires recognizing the potential for two patients which may influence resource allocation and understanding anatomic and physiologic variation that may affect diagnostic and surgical care. As such, the following review adapts ‘usual’ trauma care to include considerations for the different physiology of the pregnant patient and the wellbeing of the fetus.

Initial Assessment

Given that the most common cause of fetal loss is maternal demise, the best initial approach to trauma care is optimal resuscitation of the pregnant person [2].
Moreover, simple early measures can optimize fetal care without interrupting or substantially distracting from care of the pregnant person. Regardless of pregnancy state, initial evaluation should begin as with any trauma assessment with ‘ABC,’ airway, breathing, and circulation [3].
Primary Survey
Airway:
As with any trauma assessment, the survey should begin with an assessment of airway patency. Importantly, during pregnancy, there is substantial mucosal capillary engorgement, resulting in more friable oral mucosa and therefore great care must be taken  with oropharyngeal suctioning, airway placement, laryngoscopy, and intubation. In addition, tissue friability can rapidly contribute to upper airway edema and bleeding [4].
Consequently, if intubation is indicated, endotracheal tubes should be downsized to 6.0-6.5mm internal diameter tubing to account for edema at the level of the arytenoids that may be exacerbated by preeclampsia, increased venous pressure, or poor cardiac return. However, even in the absence of airway edema, pregnancy associated weight gain or common comorbidities such as obesity and obstructive airway disease may increase the difficulty of airway placement [1].
Given physiologic changes of pregnancy including additional fetal oxygen demand, up to 20% decrease in functional residual capacity, and 50% increase in minute volume, supplemental oxygen should be administered to the pregnant trauma with a goal saturation of >95% to ensure appropriate oxygenation of the fetus. Pregnant patients in their third trimester typically are hypocapnic at baseline (PaCO2 ~ 30 mm Hg) therefore it is prudent to recognize that a PaCO2 of 35-40mmHg can be a sign of impending respiratory failure.
In the setting of emergent intubation, four maximal breaths of 100% oxygen over 30 seconds prior to rapid sequence induction is indicated [4]. A lower dose of succinylcholine is required due to a lower concentration of pseudocholinesterase in pregnancy.
Breathing:
Due to fundal displacement of the diaphragm, breath sounds may be best heard in anterior or high axillary lung fields. During adjunctive maneuvers such as chest x-ray, all female patients of childbearing age should be shielded across the lower abdomen with a lead apron or drape when possible [5].
If indicated for pneumo- or hemothorax, the placement of chest tubes should be as high as safely possible given cranial displacement of the diaphragm with increasing gestational age [3].
Circulation:
Several critical cardiovascular changes in pregnancy may mask hemorrhage. These include an increase in circulating blood volume (40-100%), systemic capillary and renovascular dilation resulting in decreased systemic vascular resistance and lower blood pressure with widened pulse pressure, elevated heart rate, and increased cardiac output (up to 45%) [6].
In addition to these hemodynamic findings, pregnancy also is associated with baseline increase in sympathetic tone which can potentiate vasopressor resistance. Due to these expected changes, acute blood loss, may not be readily identified due to maternal compensation. Therefore, close hemodynamic monitoring and a high index of suspicion for injury should predominate throughout the initial assessment [2]. It is recommended to keep systolic >100 mmHg for the pregnant trauma patient to optimize placental perfusion.
In pregnant patients with concern for developing hemorrhagic shock, resuscitation should be initiated with emergency-release O-negative blood unless crossmatch results are available [7]. If there is concern for acute shock and a massive transfusion protocol is initiated, blood products should be administered in a balanced fashion with respect to platelets and fresh frozen plasma as with large volume resuscitation for other traumatic hemorrhage [8].
Patients should be aggressively resuscitated with colloid first, then crystalloid to avoid the use of vasopressors which can have negative effects on placental perfusion.  For obtaining access, it is best to avoid the femoral veins, as the IVC is often compressed due to the gravid uterus. Recommend aiming for subclavian or humeral as first line.
As an adjunct to the hemodynamic assessment, the patient should be positioned with deflection of the uterus off the inferior vena cava [2]. This is particularly relevant for the patient at or after 20 weeks gestation after which supine hypotension syndrome is more prevalent. In fact, at term, the inferior vena cava is almost completely occluded in the supine position and there is substantial collateral venous return via azygous, vertebral and epidural veins [4].
Nonetheless, the preload effect of substantial venous compression in pregnancy can reduce cardiac output 10-20% in the supine position which may acutely exacerbate blood loss or distributive shock in the trauma setting. That said, if the patient is more than 20 weeks, even in prehospital transport, the patient should be placed on a wedge under the right side. If there is also concern for spine injury, the wedge can be placed under the board and will still have the same effect. In addition, the use of analgesia or anesthesia for pain control or airway management may further exacerbate this hemodynamic sensitivity [4].
For the patient adhering to spinal precautions, uterine deflection can be achieved by tilting the patient and backboard to the left. For the patient with no concern for spinal instability, a left lateral decubitus position is appropriate. If these approaches are not possible such as during cardiopulmonary arrest, quick uterine displacement can also be achieved by simple manual displacement of the uterus to the patient’s left. Simultaneous to these maneuvers, a manual fundal height assessment can provide a rough estimate of gestational age (fundus above pubis ~ 12-14 weeks, at umbilicus ~20-22 weeks, at xiphoid ~38 weeks) [2].
It is also worth noting that in addition to precipitating venous obstruction, the gravid uterus can cause aortoiliac compression either secondary to a chronic May-Thurner presentation or acutely with supine positioning. Prolonged hypotension (more than 25% decrease for an average patient for greater than 10 minutes) can decrease hypogastric flow and contribute to fetal acidosis [4].
If there is concern for thoracic or abdominal bleeding several findings should be appreciated. First, a focused assessment using sonography for trauma or FAST evaluation may be employed to quickly evaluate for intracompartmental hemorrhage. Importantly, the dilation of the left and right ventricle during pregnancy result in a leftward deflection of the heart which may make it even more susceptible to penetrating injury [1]. Relevant FAST views include the subxiphoid pericardial, hepatorenal recess, perisplenic, and suprapubic windows [2].
Notably, during pregnancy, the suprapubic view may be obscured by a large uterus. In addition, small insignificant pericardial effusions may be physiologic during pregnancy; therefore, a suspicion for cardiac injury should indicate intervention for this finding [4].
Accordingly, in the stable patient, formal echocardiography may better characterize cardiac function. Second, if time permits, a quick fetal assessment may also be obtained along with the FAST if there are signs of vaginal hemorrhage to assess for major placental abnormalities, although formal fetal assessment should be deferred until after initial trauma surveys. Finally, if pharmaceutical hemorrhage control is indicated, tranexamic acid may safely be used for primary maternal hemorrhage as well as for traumatic indications [1].
Secondary Survey
After the primary trauma survey, a usual secondary survey should be undertaken. A discrepancy in fundal height and gestational age can be a sign of uterine rupture or significant hemorrhage. In addition to thorough exposure and examination of the pregnant person, an external genitalia exam is indicated to evaluate for obviously presenting fetal parts, hemorrhage, or membrane rupture.
If vaginal bleeding is noted, it is imperative to perform an ultrasound prior to a manual exam to rule out placenta previa. A relevant trauma history should be obtained and should include an obstetric history regarding previous and current pregnancy. With respect to prior pregnancies, it is helpful to know if the patient has had vaginal or caesarian deliveries and if there is a history of pregnancy complications such as placental abruption. Regarding the current pregnancy, history should include the estimated gestational age, any known fetal abnormalities or complications of pregnancy, group B streptococcus status, and for fetuses approaching term, whether any corticosteroids (e.g. betamethasone) have been given during the pregnancy.
Obstetric consultation should be obtained when available for all cases of injury in pregnant persons [2]. Regardless of specialty availability and prior FAST exam, a focused obstetrical ultrasound should be obtained after the initial survey and resuscitation of the pregnant person. Information that may be gleaned from ultrasound include fetal heart rate, gestational age, presentation, placental findings such as abruption, and obvious fetal injuries.

Extended Workup and Management

Laboratories
Routine trauma laboratories should include a comprehensive metabolic panel, complete blood count, blood type and screen, coagulation markers with fibrinogen, and urinalysis. In addition to usual traumatic findings, these laboratories may indicate the development of pregnancy-related pathology such as hematuria; disseminated intravascular coagulation; urinary tract infection; or hemolysis, elevated liver enzymes, and low platelets (HELLP syndrome) which may result from preeclampsia induced by trauma [3].
In addition to these routine laboratories, a human chorionic gonadotropin (β-HCG) should be evaluated by blood or urine testing as available for all female trauma patients of childbearing age as even the presence of an early pregnancy may alter anesthesia, surgical, or follow-up care. A Kleihauer-Betke test should be performed in all pregnant patients >12 weeks gestation and determines the presence of fetal cells in maternal circulation indicating interruption of the placental compartment and fetomaternal hemorrhage [9]. A positive finding may result in activation of the immune response of the pregnant person and isoimmunization by formation of anti-Rhesus D antibodies if the fetus is Rh-D + and the pregnant person is Rh-D –.
If untreated, future pregnancies will be at increased risk for Rh-D disease targeting fetal erythrocytes resulting in anemia, hydrops, and potential mortality. If the KB is positive or the blood type and screen reveals the pregnant person is Rh-D –, then a 300ug dose of Rh immunoglobulin therapy (RhoGAM) should be delivered as an initial starting dose. Notably, this dose will be protective in the setting of up to 30mL fetal blood contamination, but higher dosing may be required if there is evidence of massive fetomaternal hemorrhage in the setting of trauma. Finally, all RhD- pregnant persons should receive RhoGAM unless injury is distant from the uterus (e.g. isolated extremity or head injury) [2].
Radiography
Considerations for the assessment and resuscitation of the pregnant person should dictate the role for radiography. If CT scanning is indicated, it should be pursued for the safety of the pregnant person. For conditions difficult to assess on physical exam such as placental abruption in which  the placenta separates from the myometrium thereby compromising oxygenation of the fetus, CT is a reliable means of diagnosis [3]. Notably, there is no evidence that routine clinical imaging results in fetal teratogenicity but rather only that high dose radiation can result in fetal compromise [3].
Nonetheless, when feasible, lead shielding of the lower abdomen should be used during chest or extremity x-rays. In addition, minimizing radiation redundancy is of potential increased value in the pregnant person (e.g. pelvic x-ray may be deferred if there is a planned computed tomographic scan for a hemodynamically normal patient). If a radiologist is available, consultation to determine the maximal radiation dose may inform workup if multiple scans or x-rays are required.
Pregnancy Monitoring
Patients with trauma may mask injuries to the placenta or fetus that are not identified by clinical exam or ultrasound or that may present in a delayed fashion. Therefore, all pregnant persons >20 week gestation should undergo a minimum of 6 hours (ideally 24 hours) tocographic monitoring to evaluate for uterine activity and fetal heart rate trends [2].
Evidence of contractions, fetal heart rate decelerations, the development of vaginal bleeding or uterine tenderness, or rupture of amniotic membranes are concerning findings that warrant admission and observation for potential delivery.
Corticosteroids
If delivery is imminent and the gestational age of the fetus is estimated 23-34 week gestation, 12mg of intramuscular betamethasone should be administered immediately and repeated 24 hours later is possible to promote fetal pulmonary maturity prior to delivery [2].

General Considerations for Operative Management

As it may be difficult to assess for isolated pregnancy-related hemorrhage in the trauma setting, the hemodynamically unstable pregnant trauma patient should be promptly taken to theater for operative evaluation as with any trauma. If by way of imaging and history it is possible to identify an isolated pregnancy-related complication (e.g. blunt extremity trauma and concomitant uterine abruption), then usual obstetrical management principles may predominate. Given a blunted response to peritonitis, exploration should be considered for all penetrating injuries to the upper abdomen [3].
Emergency caesarean section is indicated for fetuses of at least 23-24 weeks gestation with intact fetal heart tones with obstetric indications of distress if an attempt at delivery does not jeopardize the outcome of the pregnant person. In addition, if there are no indications for delivery such as fetal distress or premature rupture of membranes, caesarian delivery is not routinely recommended at time of exploratory celiotomy. Furthermore, patients with evidence of fetal bradycardia should not undergo caesarian delivery until stabilization of the pregnant person but if there are concomitant indications for operative intervention such as hemodynamic instability or thoracoabdominal injury in the pregnant person, delivery may be indicated intraoperatively.
In the setting of burns, increasing total body surface area (TBSA) burn percentage is associated with fetal mortality. If there are greater than 55% TBSA burns, urgent caesarian delivery is indicated without delay for corticosteroids. If there is carbon monoxide exposure or evidence of airway injury, early intubation is indicated given edematous airway mucosa physiologic to pregnancy. Finally, usual fluid resuscitation in burns may have to be increased by 30-60% for the pregnant person and should be directed by urine output.
Perimortem caesarean section is indicated in the moribund pregnant patient with gestational age 23-24 weeks, must occur within 20 minutes of maternal arrest, and ideally occurs within 4 minutes [3]. This recommendation is given by the AHA and ACOG with the thought being that early c-section may lead to a successful resuscitation of the mother with the weight of the uterus off the aorta and IVC. Given this, CPR should continue through the delivery.
The caesarean section should be performed in the same location, as to not waste time by transporting the patient to the operating room. A generous midline incision should be used, and the uterus opened with a vertical incision. The head is then delivered, and the rest of the fetus removed from the uterus. Clamp the cord and hand off the baby. Remove the placenta. The uterus can be closed with a single layer running PDS or chromic suture. CPR should continue and re-evaluate for maternal signs of life. There are no changes to noninvasive cardiopulmonary life support approaches except that the uterus should be manually displaced to the patient’s left for aortocaval decompression. Perimortem caesarean section may be carried out simultaneous to resuscitative thoracotomy; particularly as aortic cross-clamping for hemorrhage control immediately risks the fetus.
Resuscitative thoracotomy should follow usual trauma principles. However, consideration for a displaced diaphragm and leftward displaced heart may challenge usual exposure [3]. A higher-than-normal incision may be necessary at or above the nipple line. Identification of the inferior pulmonary ligament may be challenging due to cardiac deflection and the presence of the pregnant abdomen.
Exploratory celiotomy should follow usual trauma principles. Broad exposure is essential as the gravid uterus may displace abdominal contents. Traumatic hemorrhage control should be obtained in the usual fashion with four-quadrant packing [3]).
Frank uterine rupture may range from serosal hemorrhage to avulsion of the uterus or disruption of the myometrium with intraabdominal fetal extrusion and evidence of massive uterine hemorrhage or perforation may require caesarian delivery and usual pharmaceutical and manual induction of contraction [8].
If this is inadequate for control, obstetric management options include uterine artery ligation (or embolization if available), B-lynch sutures, intrauterine balloon tamponade, or hysterectomy [4]. Evaluation of retroperitoneal zones and vascular exposure may be challenged by the gravid uterus and may also require delivery.

Summary

  • The best initial approach to trauma care is optimal resuscitation of the pregnant person and should begin with ‘ABC,’ airway, breathing, and circulation
  • Careful airway manipulation and oxygenation prior to intubation are of particular importance during pregnancy
  • Thoracic interventions should be modified based on knowledge of diaphragmatic displacement due to the gravid uterus
  • Close hemodynamic monitoring and a high index of suspicion for injury should predominate throughout the initial assessment
  • Manual or positional leftward deflection of the gravid uterus can decompress acute aortocaval compression and facilitate hemodynamic management
  • Formal fetal assessment should follow assessment of the pregnant person; an obstetrics consult should be obtained for any pregnant trauma patient
  • Laboratory evaluation should include a Kleihauer-Betke test followed by administration of rhesus D immunoglobulin if indicated
  • Corticosteroids should be delivered if possible, for appropriate gestational age fetuses
  • Stable patients with trauma should undergo a minimum of 6 hours of fetal monitoring
  • Emergency caesarean section is indicated for fetuses of at least 23-24 weeks gestation with intact fetal heart tones with obstetric indications of distress if intervention does not place the pregnant person at risk
  • Perimortem caesarean section is indicated in the moribund pregnant patient with gestational age 23-24 weeks, must occur within 20 minutes of maternal arrest, and ideally occurs within 4 minutes
  • Trauma principles with respect to the pregnant person should dictate care; however intraoperative caesarian delivery may be indicated for fetal distress, uterine disruption, or for gaining appropriate injury exposure in the pregnant person

References

  1. Huls CK, Detlefs C. Trauma in pregnancy. Seminars in Perinatology. 2018 Feb 1;42(1):13–20.
  2. Pregnancy and Trauma – Practice Management Guideline [Internet]. [cited 2022 Mar 19]. Available from: https://www.east.org/education-career-development/practice-management-guidelines/details/pregnancy-and-trauma
  3. Beldowicz BC, Leshikar D, Cocanour CS. Trauma in Pregnancy. In: Feliciano DV, Mattox KL, Moore EE, editors. Trauma. 9th ed. New York, NY: McGraw Hill; 2020.
  4. Pardo M, Miller RD. Basics of Anesthesia. Elsevier Health Sciences; 2017.
  5. Murphy NJ, Quinlan JD. Trauma in Pregnancy: Assessment, Management, and Prevention. AFP. 2014 Nov 15;90(10):717–22.
  6. Sanghavi M, Rutherford JD. Cardiovascular Physiology of Pregnancy. Circulation. 2014 Sep 16;130(12):1003–8.
  7. Schantz-Dunn J, M N. The Use of Blood in Obstetrics and Gynecology in the Developing World. Rev Obstet Gynecol. 2011;4(2):86–91.
  8. Mirza FG, Devine PC, Gaddipati S. Trauma in Pregnancy: A Systematic Approach. Am J Perinatol. 2010 Aug;27(7):579–86.
  9. Krywko DM, Yarrarapu SNS, Shunkwiler SM. Kleihauer Betke Test. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 [cited 2022 Mar 19]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK430876/