Trauma affects nearly one in 12 pregnancies, with motor vehicle collisions and intimate partner violence being the most common causes. Aside from pregnancy-related issues, trauma is the leading cause of maternal death. Fetal death secondary to maternal trauma affects 2.3 per 100,000 live births, often stemming from placental abruption. Injuries necessitating trauma activations are associated with increased risk of preterm birth, placental abruption, poor infant condition at birth, as well as infant and maternal death.

Studies suggest that multidisciplinary care for a pregnant orthopaedic trauma patient should include an obstetrician, perinatologist, orthopaedic surgeon, general trauma surgeon, critical care specialist, emergency medicine specialist, anesthesiologist, and a radiologist. Due to their need for specialist care and so as not to delay appropriate care, pregnant patients may benefit from being diverted to trauma centers directly from the scene of injury rather than being transferred later from another facility.

Physiologic changes in pregnancy

In the pregnant patient, the uteroplacental interface increases the body’s oxygen demand. Increases in the blood volume and baseline heart rate work to meet this demand by producing greater cardiac output. Elevated blood levels of progesterone contribute to smooth muscle relaxation and result in decreased blood pressure. While the blood volume increases by 40 percent to 50 percent, the number of red blood cells increases by only 30 percent, producing what is commonly known as pregnancy-related anemia. These hemodynamic changes occur to prepare for the expected blood loss of child birth; however, in the setting of trauma, these changes can mask impending shock. Because pregnant women can lose up to 2,000 mL of blood with minimal changes in pulse or blood pressure, it is essential to perform a thorough physical exam.

At term, the gravid uterus weighs 4,500 grams on average and may compress the inferior vena cava (IVC) in the supine position, leading to decreased preload and cardiac output. Pregnant patients should be positioned in the left lateral decubitus position during the management of trauma. In cases where this positioning is not feasible, external manual manipulation of the uterus may alleviate compression of the IVC.

Elevated estrogen during pregnancy induces hepatic production of coagulation factors, which creates a hypercoagulable state. Additionally, increased body mass index in pregnancy is an independent risk factor for deep vein thrombosis after trauma. The pressure of the uterus on the IVC increases the likelihood of venous stasis in the lower extremities, and with trauma, patients may incur vascular injury to complete Virchow’s triad. Care must be taken to implement appropriate prophylaxis for blood clots, including low-dose heparin, sequential compression devices, and early ambulation.

The pulmonary system also undergoes significant changes during pregnancy. A byproduct of increased blood volume is swelling of the upper airway, which may make intubation in an emergency more difficult. Along with narrowed airways, the superior displacement of the diaphragm by the gravid uterus and reduced lung capacity contribute to an increased respiratory rate. These changes result in diminished oxygen reserve, putting the mother and fetus in danger of hypoxia. In light of this, physicians should have a low threshold for intubation.

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Maternal resuscitation

The trauma evaluation should follow advanced cardiac life support protocol. Maternal shock is closely associated with fetal death, so initial evaluation should focus on appropriate maternal resuscitation. Fetal assessment can then be performed, followed by a secondary survey of the mother. Lastly, definitive management for any injuries should be initiated.

Primary interventions in caring for the pregnant trauma patient must consider the gravid uterus. Lateral decubitus positioning is the first step toward increasing venous return and cardiac output in the acutely injured patient. Vasopressors should be reserved only for intractable hypotension after fluid resuscitation efforts have been exhausted, as these medications have an adverse effect on uteroplacental perfusion. Placement of a nasogastric tube can prevent aspiration by decompressing the stomach, which is subject to increased intra-abdominal pressure. All pregnant trauma patients should be placed on oxygen, as the fetus is particularly sensitive to maternal hypoxia and oxygen delivery is compromised at baseline. In situations where a chest tube is warranted, care must be taken to place the tube one to two intercostal spaces above the normal target because of the superior displacement of the diaphragm.

Initial evaluation of a pregnant trauma patient should include a coagulation profile, as abnormalities in these labs can be an indication of maternal hemorrhage. A baseline coagulation profile is useful in excluding disseminated intravascular coagulation, a potential sequelae of placental abruption. Rhesus (Rh) typing may be performed at this time, and rhogam can be given to suppress the immune response of exposure to fetal blood in the Rh-negative mother.

Radiographic considerations

Adequate imaging should not be deferred or delayed for the sake of the fetus. A missed or incorrect diagnosis is a more likely cause of poor fetal outcome than the radiation dose the fetus is exposed to in routine imaging procedures. Radiation exposure has a dose-dependent and gestational age-dependent effect on the fetus, with the most significant risk of teratogenesis occurring during weeks three to eight, which corresponds with the period of major organogenesis. The potential carcinogenic effect of radiation is also highest during organogenesis, and exposure to > 30 mGy has been found to increase cancer risk in one of 500 fetuses. Because the developing central nervous system is most sensitive in weeks eight to 15, toxic levels of radiation during this interval may result in growth retardation and lower intelligence (Table 1).

Radiation of five to 10 rads (or 50-100 mGy) has been shown to have teratogenic effects. An anteroposterior pelvis radiograph exposes the fetus to less than 0.2 mGy of radiation. Advanced imaging such as fluoroscopy or computed tomography (CT), however, expose the fetus to much higher levels of radiation. For example, a chest CT scan exposes a fetus to 4.5 mGy, and a pelvic CT scan exposes a fetus to 35 mGy. Other imaging modalities, such as MRI, which is safe to use during pregnancy, may be considered if the anatomy in question can’t be adequately assessed otherwise.

Radiation exposure should be limited, especially early in pregnancy, and this consideration may dictate surgical management. If the gestational age and anatomic position of the fracture in a pregnant patient places the fetus at risk for excessive radiation exposure, the orthopaedic surgeon may consider performing the procedure that would require the least amount of radiation (e.g., an external fixator over intramedullary nailing).

Anesthetic considerations

When surgery is warranted, efforts must be maximized to avoid maternal hypotension and secondarily fetal hypoxia with both positioning and anesthetic choice. Halogenated agents have an amplified effect in the pregnant patient, therefore, dosages may need to be reduced by as much as 40 percent. Anesthetics also have potentially teratogenic effects, with the highest risk during organogenesis.

Fetal monitoring

As early as 10 weeks, the fetal heart rate can be heard via Doppler. For pregnant patients who are at more than 23 weeks of gestation (the gestational age of viability), continuous fetal monitoring should be performed for four hours as long as it does not interfere with maternal resuscitation and interventions. For the fetus that is less than 23 weeks of gestation, this noninvasive monitoring can be discontinued after confirmation of a heartbeat. Continued fetal monitoring is warranted, however, in situations where maternal cardiopulmonary function is compromised or at risk. Maternal blood pressure is preserved at the expense of uterine blood flow in cases of acute blood loss. Fetal distress can therefore be the index sign of maternal hemorrhage.

Conclusion

Many facets of resuscitation and treatment of a pregnant orthopaedic trauma patient are similar to that of any trauma patient; however, consideration of the physiologic changes during pregnancy can improve outcomes for both the mother and fetus. Frequent and thorough monitoring of maternal vital signs and serial physical exams are important, as changes in status can happen abruptly. Diagnostic imaging studies rarely meet radiation thresholds that would result in teratogenic or carcinogenic effects to the fetus, thus appropriate studies should not be deferred. It is important to consider gestational age and radiation burden when ordering scans and during surgical planning to ensure the most benefit to the patient with the least radiation exposure to the fetus. The surgical team can minimize risk to the fetus and maximize benefit to the mother with appropriate positioning, technical surgical choice, and consideration of teratogenic effects of diagnostic studies.

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Kelly L. Hill, MD, is an orthopaedic surgery resident at the Tulane University School of Medicine.

Karen M. Sutton, MD, is an associate attending orthopaedic surgery, sports medicine at Hospital for Special Surgery, where she is part of the Women’s Sports Medicine Center. She is also a member of the AAOS Women’s Health Advisory Board.

Mary K. Mulcahey, MD, is an associate professor in the Department of Orthopaedic Surgery and director of the Women’s Sports Medicine Program at the Tulane University School of Medicine.