The main priorities in prehospital care continue to be the avoidance of hypoxia and hypotension in the mother. Maintenance of an adequate airway, as well as provision of supplemental oxygen, is essential in avoiding fetal hypoxia. Circulatory support with crystalloids is recommended and should be initiated early. The relative hypervolemic state of pregnancy means that a large-volume blood loss can occur prior to the development of signs of shock. Displacement of the uterus off the inferior vena cava (IVC) or tilting of the patient with a wedge may be required to augment cardiac return. A detailed obstetric history including length of gestation, prenatal care, complications, and names of care providers can be valuable information for the trauma team.

During the trauma evaluation, the priorities in patient management remain the same in the pregnant patient as in the nonpregnant patient. Adequate oxygenation of the mother, by ensuring an adequate maternal airway with supplemental oxygen, best ensures the adequate oxygenation of the fetus. Access for resuscitation can be achieved with peripheral IVs or subclavian or jugular venous central access. Blood loss should be treated with crystalloid and blood transfusion following the principles of damage control and balanced resuscitation, with an emphasis on early use of blood and blood products in the event of life-threatening hemorrhage.^24,25

In the secondary survey, a complete physical examination is essential. In addition to a complete examination for maternal injuries, complete examination of the fetus includes estimation of uterine size and fundal height, examination for vaginal bleeding, rupture of membranes, presence of bulging perineum, contractions, or abnormal fetal heart rate (FHR) or rhythm. Vaginal bleeding may be an indicator of premature cervical dilation, early labor, abruption placentae, or placenta previa. Cloudy white or green fluid from the cervical os may represent amniotic sac rupture. A vaginal speculum examination should be performed to assess for cervical dilatation and bleeding from the cervical os. Strong contractions, or bulging of the perineum (due to the presenting part of the fetus) can signal imminent delivery (or abortion in early pregnancy).

A thorough medical and obstetric history is required for all patients in whom it can be obtained. An accurate date of last menstrual period and expected delivery aids in measurement of uterine size, height, and position. A history of complications of the present or previous births, such as hypertension, preterm labor, abruption placentae, or placenta previa aids in evaluation and management, due to the high rate of recurrence.

Options for evaluation of the fetus include Doppler FHR monitoring or ultrasound. Normal FHR ranges from 120 to 160 beats/min. Tachycardia (>160 beats/min) is seen during stress, hypoxia, or hypotension, however bradycardia (<120 beats/min) also indicates fetal distress and mandates immediate maternal resuscitative efforts including supplemental oxygen, fluid, or blood administration. Fetal heart monitoring should be performed in all potentially viable fetuses involved in a traumatic abdominal injury.

Airway

Increased metabolic needs of the mother and fetus lead to a 30% to 60% increase in oxygen consumption. This in combination with decreases in functional expiratory reserve volume and functional residual capacity due to the enlarged uterus and upward pressure on the maternal diaphragms leads to decreased overall respiratory reserve and can result in rapid onset of hypoxia of mother and fetus.

The average pregnant patient gains about 17% of body weight during pregnancy.²⁶ This results in an overall increase in BMI from fat and protein deposition, blood volume, interstitial fluid, and uterine size. The resulting increase in Mallanpati scores may complicate airway management and result in morbidity due to failed intubations.²⁷ Raised progesterone levels also increase total-body water and result in generalized edema, including edema of the airway. Edema of the tongue, oropharynx, and trachea may impair visualization and intubation of the airway, further complicating intubation. These changes progressively increase with increasing gestational age.²⁸ Gastric compression due to increased fundal height and lower esophageal sphincter dysmotility contribute to an increased risk of aspiration and early intubation should be considered for at-risk patients. Preoxygenation, cricoid pressure, and avoidance of bag-mask ventilation when possible are recommended.

Cardiovascular System

4 Beginning at 10 weeks of gestation, intravascular blood volume increases steadily over the course of pregnancy, reaching up to 50% above normal by term.²⁹ The increase in plasma volume is relatively greater than the approximately 15% increase in red blood cell (RBC) mass initially; therefore a relative physiologic anemia is seen during early pregnancy. However, erythrocyte production increases later in pregnancy, and after a nadir at 30 to 32 weeks, hematocrits are near normal by term. The relative hypervolemia of pregnancy can mask large-volume hemorrhagic losses and up to 35% of maternal blood loss can be lost prior to signs and symptoms of shock. Pulse rates increase by 10 to 15 beats/min and remain elevated until delivery.

5 As the gravid uterus increases in size, supine positioning can result in “supine hypotensive syndrome” resulting in compression of the IVC and decreased blood return to the heart, resulting in up to a 30% decrease in cardiac output. Symptoms include lightheadedness, dizziness, pallor, tachycardia, and hypotension. Displacing the uterus laterally to the left of the patient, either manually or by use of a wedge to tilt the patient >15 degrees to the patient’s left can restore perfusion.

Fluid resuscitation is the first-line therapy for the unstable pregnant trauma patient. Catecholamine release preserves the maternal blood pressure through maternal peripheral vasoconstriction, but decreases fetal blood flow via placental vasoconstriction. Adequate access is essential in the injured pregnant patient, as decreased fetal blood flow precedes maternal hypotension.³⁰ Two large bore intravenous lines, preferably above the diaphragm, should be placed initially. Adjustments must be made for the relative hypervolemia of pregnancy and fetal distress can precede maternal instability. Blood and blood product transfusion should be considered early in the unstable trauma patient. Type O, Rh-negative blood should be used until type specific or cross-matched blood is available. In the resuscitated, euvolemic patient, if pressor support is required, ephedrine and phenylephrine have the least effect on uterine-placental vasculature and are recommended for initial pressor support in pregnant patients. Additional pressors such as norepinephrine and epinephrine can be considered in the unstable patient, especially in those without a viable pregnancy.³¹

Compression of the IVC by the gravid uterus decreases venous return to the heart and can decrease cardiac output by up to 30%. During cardiopulmonary resuscitation (CPR), lateral displacement of the uterus to the patient’s left can improve hemodynamics and CPR efforts. In late pregnancy (>24 weeks), use of a foam wedge or padding to tilt the patient up to 30 degrees to her left can be helpful, though CPR is only 80% effective in this position. Standard Advanced Cardiac Life Support (ACLS) voltage should be used if defibrillation is required.

Pulmonary System

Increased intra-abdominal pressure from the growing uterus causes elevation of the diaphragm and results in a decrease in total lung capacity and functional residual capacity. This results in a compensatory chronic hyperventilation with 30% to 40% increase in minute ventilation. The resultant chronic respiratory alkalosis facilitates transfer of fetal CO₂ to the maternal circulation. Overaggressive correction of respiratory acidosis in the mother can have deleterious effects on the fetus.³² Hypocapnia (PaCO₂ of <30 mm Hg) is common in pregnancy and a “normal” CO₂ (∼40 mm Hg) may be a sign of imminent respiratory failure. Oxygen consumption is increased approximately 20% in pregnancy and needs to be accounted for in oxygen supplementation.

Elevation of the diaphragm late in pregnancy requires care to be taken when thoracostomy tube placement or thoracentesis is required. Chest tubes for hemo- or pneumothoraces require higher placement and should be inserted in the third or fourth intercostal space.

Ventilatory support, when required, should be individualized to optimize oxygenation and avoid acidosis. There are no studies addressing the ideal way to manage ventilatory support in pregnant patients with acute lung injury or ARDS. While lung protective strategies may be beneficial, hypercapnea in these patients should be avoided.

Gastrointestinal System

The growing uterus causes progressive gastric compression as the pregnancy progresses. Increased progesterone levels in pregnancy result in decreased function and tone of the lower esophageal sphincter, as well as decreases in gastric tone and motility. This places the mother at increased risk of aspiration, especially during intubation. During intubation, rapid sequence induction is recommended given the high risk of aspiration. High levels of progesterone decrease gallbladder contractions and lead to bile stasis and formation of gallstones.

Genitourinary System

Renal function increases to meet the demands of increased circulatory volume during pregnancy. Renal blood flow and glomerular filtration rates (GFRs) increase by 50% to 60% and levels of blood urea nitrogen (BUN), creatinine, urate, and bicarbonate are decreased. Increased water retention causes decreased plasma osmolality. Relaxation of the bladder smooth muscle increases capacity, stasis, and the risk of development of urinary tract infections and pyelonephritis.^33,34

Hematologic System

Increased intravascular volume relative to RBC production leads to a physiologic anemia with an average hematocrit of 32 during the first two trimesters. This corrects to near normal hematocrit levels by term. White blood cell counts (WBCs) also are relatively increased and can range from 9,800 to 15,000/mm3.

Increased estrogen levels lead to increased production of factors VII, VIII, IX, X, and XII and plasma fibrinogen levels are elevated about 30% to 50%. Plasminogen activator levels are decreased. Protein S activity is decreased and protein C activity is increased.³⁵ This leads to the “hypercoagulable” state of pregnancy and places these patients at increased risk of deep venous thrombosis (DVT) and pulmonary embolism (PE), with slower resolution and lysis of clot. Normal levels of coagulation factors should raise the suspicion of disseminated intravascular coagulation (DIC).

6 During trauma, entry of fetal Rh+ blood (as little as 0.07 mL) into the blood stream of an Rh− mother results in formation of antibodies. These antibodies, while harmless to the mother, can reenter the bloodstream of the fetus (or subsequent pregnancies) and cause hemolysis of the fetal RBCs. Prophylactic anti-D immune globulin (RhoGAM^TM) should be given within 72 hours of trauma when significant risk of maternofetal hemorrhage exists. A Kleihauer–Betke (KB) analysis should be performed for all pregnant patients with >12 weeks of gestation.^36,37 A study out of University of Maryland showed a positive KB was the single predictive risk factor for preterm labor with a likelihood ratio of 20.8.³⁸

MONITORING AND EVALUATION OF THE FETUS

Pregnancies beyond 24 weeks of gestation are considered viable, and an expedient estimation of gestational age is required. Patient history, fundal height, or ultrasonographic measurement of femur length (in the third trimester) or biparietal measurements can be used.

Optimal management of the pregnant mother results in the best chance of survival of the fetus. However, studies showing fetal death rates can be several fold greater than maternal deaths rates in trauma suggest that maternal survival in itself is not sufficient. Close monitoring of the viable fetus is necessary. Continuous fetal monitoring is the only way to identify fetal distress in the acute setting.³⁹ The Eastern Association of Surgery for Trauma (EAST) guidelines recommend monitoring of all pregnant female with gestation >20 weeks for at least 6 hours after significant trauma.⁴⁰ Early involvement of the neonatal intensive care staff is recommended.

RADIOGRAPHIC IMAGING IN TRAUMA

The ideal diagnostic imaging test in the pregnant patient should be fast, readily available, safe, and accurate. Selection of the appropriate test needs to balance the need for expedient diagnosis while minimizing risk to mother and fetus. During pregnancy, radiation exposure should be avoided or minimized whenever possible. Exposure to less than 5 rad of radiation has not been associated with fetal anomalies or pregnancy loss, and is safe at any gestation age.⁴¹ With proper shielding, however, minimal radiation is transmitted to the fetus with plain films (Chart 31-4).

7 Sonographic evaluation of both the mother and fetus is safe and useful in determining the extent of injuries. FAST ultrasound has excellent specificity and negative predictive value in detecting pericardial, pleural, and peritoneal free fluid in the hemodynamically unstable mother and poses no risk to the fetus.⁴² Ultrasound is particularly useful in the evaluation of intrauterine contents, but can miss 50% to 80% of placental abruptions.⁴³ Fetal ultrasound should be performed to assess for gestational age, cardiac activity, and movement.

CT scans are rapid and sensitive for evaluation of traumatic injuries. CT scans of the head and neck can be performed with minimal radiation exposure to the fetus. As radiation exposure levels from CT scans of the chest, abdomen, and pelvis can be variable, the use of CT should be minimized whenever possible. However, CT imaging should be performed when appropriate for complete evaluation of traumatic injuries. Practitioners should utilize radiation reduction strategies whenever possible.⁴⁴

Magnetic resonance imaging (MRI) poses minimal risk to the fetus and may have a role in the evaluation for ligamentous injuries of the spine and spinal cord injuries. However, use of this modality is limited due to availability and length of time required to perform. Additionally, the MRI scanner is often remote from the resuscitation area, and ongoing resuscitative efforts may not be feasible when the patient is undergoing MRI. Therefore, MRI should only be utilized in hemodynamically normal patients without ongoing resuscitation requirements.

8 Angiography and angioembolization may be useful in the event of life-threatening hemorrhage, but radiation dose increases with increasing duration and extent of evaluation. Typical exposure ranges from 2 to 10 rad/min, and the risk versus benefit needs to be carefully weighed, and patients appropriately counseled. Embolization of the gravid uterus is not recommended, however embolization of the nonuterine vessels is feasible and can be life-saving in pelvic fractures with ongoing hemorrhage.⁴⁰

In counseling patients and families, healthcare providers should emphasize that the radiation exposure from a single diagnostic test is not sufficient to cause harmful effects to the fetus, and that concerns regarding possible effects of radiation should not prevent the use of medically indicated diagnostic studies.⁴⁵

SPECIAL CONSIDERATIONS

Pelvic Fractures

Pelvic fractures in pregnancy are associated with a high rate of hemorrhage and up to 35% fetal mortality in trauma.⁴⁶ Engorgement of the pelvic venous complex during the relative hypervolemia of pregnancy can result in massive, life-threatening hemorrhage in the event of pelvic trauma, including fetal death due to maternal shock.⁷ Direct injury to the uterus can result in placental abruption or injury to the fetus. The most common fetal injury is traumatic brain injury, especially late in pregnancy as the fetal head descends into the pelvic inlet. Angiography and angioembolization are useful adjuncts in the management of life-threatening pelvic hemorrhage.

Stay updated, free articles. Join our Telegram channel

Join