Case Study
A 27-year-old primiparous woman at 31 weeks gestation was involved in a road traffic collision (RTC). She was the front seat passenger in a car that came off the road and hit a tree at 40–50 mph. She required extrication by the fire service and received oxygen, spinal immobilization, femoral traction, morphine, and ketamine in the prehospital phase. She was secured to a scoop stretcher tilted to 30 degrees to the left to avoid aortocaval compression and triaged to a major trauma center. On arrival, her vital signs were heart rate 116 beats/min, blood pressure 105/84 mmHg, SpO2 100% on 15 liter/min oxygen, and a Glasgow Coma Score (GCS) of 13 (E3 V4 M6). She was complaining of some tenderness over the left chest wall, and there was clinical evidence of a closed fracture of the right femur.
The patient was received by the trauma team and, following a primary survey, was taken to the CT scanner, where she underwent CT scanning of her head, neck, chest, abdomen, and pelvis. This revealed a simple pneumothorax on the left and a grade 3 splenic laceration with extravasation of contrast material into surrounding hematoma. Tranexamic acid 1 g was administered as a bolus, followed by an infusion of 1 g over 8 hours.
The patient was transferred to the interventional radiology suite for angioembolization of her spleen. On arrival, her blood pressure was 88/60 mmHg, and a massive transfusion protocol was activated. Preparations were made for emergency cesarean delivery, and in the absence of an appropriate wedge, manual uterine displacement was performed. The patient received 2 units of O-negative blood and 2 units of AB fresh frozen plasma (FFP) through a fluid warmer, following which her blood pressure increased to 124/80 mmHg. Angioembolization proceeded uneventfully, and the patient received a further 2 units of FFP and blood. She was transferred to the ICU following her stabilization for ongoing monitoring. A senior midwife and obstetrician were consulted to monitor the fetus using cardiotocographic monitoring. Fortunately, the fetal heart rate remained normal, and there was no clinical evidence of placental abruption. The mother was questioned regarding antenatal anti-Rhesus D (RhD) immunization, and because she had already received the 28-week dose, she was given the 34-week dose prior to her transfer to the labor ward
Key Points
This patient had a significant mechanism of injury and sustained polytrauma. Clinicians need to have a high incidence of suspicion in such cases, and occult injuries should be anticipated.
The patient required rapid comprehensive imaging to identify all her injuries based on the fact that she was tachycardic and had a reduced GCS. High-quality CT imaging of all organs was appropriate, regardless of the fact that the woman was pregnant.
Following deterioration, she was resuscitated with blood and blood products, while preparing for emergency surgical delivery of the fetus.
Thankfully, there was a good response to resuscitation and maneuvers aimed at reducing aortocaval compression, making emergency cesarean delivery unnecessary.
Two potential patients mean that the multidisciplinary team should include senior obstetric and midwife support and monitoring.
Discussion
It is difficult to know the true incidence and epidemiology of trauma during pregnancy, and a recent meta-analysis has noted the many shortcomings of the published literature. These include publication bias, the retrospective nature of all the studies, and wide variations in the outcomes reported. Nevertheless, it has been reported that trauma is now the most common cause of non-obstetric maternal death in the United States, and complicates approximately 6 percent of pregnancies worldwide. Unlike many other causes of death, it is increasing in frequency. Motor vehicle accidents and non-accidental injury due to domestic violence are the most common reported causes, with falls also common.1 As pregnancy progresses, patterns of injury change, with predominantly blunt abdominal injuries becoming increasingly common, whereas the incidence of head injury falls.2
Transport of seriously injured patients to a major trauma center is associated with a reduction in mortality.3 Most trauma systems select patients for direct transport to a major trauma center on grounds of altered physiology, apparent injuries, mechanism of injury, and patient factors such as age, pregnancy, and comorbidities. The exact inclusion criteria vary both nationally and internationally. The current London Major Trauma decision tool states that ambulance crews should assess special patient or system considerations following trauma. If the woman is more than 20 weeks’ pregnant, she will be taken to a major trauma center for assessment, even if the rest of the decision tree suggest that the patient could be managed locally.4
The initial approach to the severely injured pregnant patient is almost identical to that in the non-pregnant patient. A structured primary survey should be performed and immediately life-threatening injuries identified and treated, but CT imaging should proceed if indicated because the treatment of the mother takes priority over radiation risk to the fetus. Comprehensive early CT imaging of polytrauma patients is associated with lower mortality.5
Physiology of Pregnancy and Hemorrhage
The physiologic changes of pregnancy are adaptive for surviving hemorrhage but may make detection of hypovolemia more difficult. Increases in both blood volume and erythrocyte count of 50 and 30 percent, respectively, mean that pregnant women have a physiologic anemia due to hemodilution, both of which may provide a degree of protection from blood loss. This may mean that by the time of decompensation due to blood loss, the intravascular volume and red cell deficit may be very substantial. Cardiac output is increased by up to 50 percent by the beginning of the first trimester, and this is coupled with a reduction in systemic vascular resistance and increased uterine blood flow. The uterine blood flow is not autoregulated, and is thus entirely dependent on maternal blood pressure. Aortocaval compression, which can occur from the twentieth week of pregnancy, can impair venous return to the right side of the heart, significantly reducing both cardiac output and blood pressure in the mother, with obvious deleterious effects on the fetus. These factors, coupled with the increase in metabolic rate of up to 20 percent in the pregnant mother, mean that by the time the blood pressure begins to fall, shock is advanced, with both limited reserves and increased oxygen consumption. Speedy and effective resuscitation, including uterine displacement and consideration of operative delivery, is required to save the life of the mother.
In the non-pregnant patient, it should be noted that the likelihood of requiring blood transfusion following injury increases progressively as systolic blood pressure falls below 110 mmHg, this being a more logical definition of hypotension in trauma.6 However, fluid resuscitation prior to hemorrhage control is associated with increased hemorrhage, and many clinicians would advocate resuscitation that aims for a systolic blood pressure of less than 100 mmHg until definitive surgical or radiologic control of bleeding has been achieved. The relatively low number of traumatically injured pregnant women seen in both emergency and radiology departments means that staff may be unfamiliar with the need to correctly position the patient to avoid aortocaval compression, and this may precipitate hemodynamic deterioration and even cardiac arrest. Should this occur, the cause should be addressed. Chest compressions may be easier to perform in the supine position, with lateral manual displacement of the uterus.7
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