Chapter 12 – Trauma in Pregnancy




Abstract




The pregnant patient represents a double resuscitation, as there are two patients to simultaneously consider. Fetal resuscitation is dependent upon adequate maternal resuscitation and stability and ongoing monitoring of both patients is essential for optimal outcomes. The pregnant trauma patient poses additional challenges because the anatomy and physiology are different from the nonpregnant patient, and this affects the physical exam, the clinical presentation, and the management of the patient.





Chapter 12 Trauma in Pregnancy


Alessandra Conforto and Elizabeth R. Benjamin



Introduction


The pregnant patient represents a double resuscitation, as there are two patients to simultaneously consider. Fetal resuscitation is dependent upon adequate maternal resuscitation and stability and ongoing monitoring of both patients is essential for optimal outcomes. The pregnant trauma patient poses additional challenges because the anatomy and physiology are different from the nonpregnant patient, and this affects the physical exam, the clinical presentation, and the management of the patient.


All women of childbearing age should be considered pregnant until proven otherwise. A urine or serum pregnancy test should be obtained as soon as is feasible on all female patients of childbearing age in the setting of trauma, as self-reporting of the gravid state is notoriously untrustworthy.


Identifying the viable pregnancy early in the trauma resuscitation (i.e., level of the uterus fundus or fetal ultrasound) is essential to providing adequate care to both the fetus and the mother. Under 22 weeks of gestational age, the pregnancy is deemed nonviable, and resuscitative efforts of the fetus are futile and should be withheld. A gestational age greater than 26 weeks is associated with a high likelihood of survival. The timeframe in between these two dates is associated with variable chance of survival and management is adjusted accordingly. As a general rule, if the fundus of the uterus is two to three fingerbreadths above the umbilicus, the fetus is viable.


Trauma in pregnancy is associated with increased morbidity and mortality for both the fetus and the mother. Even after fairly minor trauma, there is significant risk of placental abruption, uterine rupture, and maternal or fetal death. A multidisciplinary approach including emergency medicine, trauma surgery, obstetrics, and neonatology will ensure the best outcome.



Epidemiology


Trauma is common during pregnancy, affecting one in 12 pregnancies, and trauma is the leading nonobstetric cause of death in pregnant patients, responsible for approximately 46% of all maternal deaths.


The most common causes of traumatic injuries in pregnant women are motor vehicle collisions, domestic violence, assault, and falls. Education regarding proper positioning of the seat belt over the gravid uterus may reduce the incidence and severity of motor vehicle-related trauma, and violence awareness and screening programs are integral to the awareness and prevention of domestic abuse (Figures 12.1 AB, Figures 12.2 AC).





Figures 12.1 A–B Intentional trauma in pregnancy is common in many societies. Pregnant patients with knife wounds to the abdomen.





Figures 12.2 A–C Pregnant patient with a gunshot wound to the abdomen (A). Emergency laparotomy revealed a through and through, wound to uterus (B, C). In this situation, if the fetus is viable by gestational age, a cesarian section should be performed.


Blunt trauma, even in the absence of significant maternal abdominal injuries, can result in placental disruption and fetal loss. In addition to acute findings, trauma to the pregnant patient can result in premature labor and low birth weight delivery and victims of domestic violence can have repeat events. For these reasons, in the setting of traumatic injury, pregnancies should be closely monitored even after discharge.



Anatomical Changes of Pregnancy


The uterus is completely protected within the pelvic ring during the first 12 weeks of gestation. As the pregnancy progresses, the uterus grows within the abdominal cavity and becomes more vulnerable to blunt and penetrating trauma. An important landmark is the uterine fundus is palpable at the umbilicus at approximately 20 weeks of gestational age (Figure 12.3). In advanced pregnancy, the uterus displaces the intestine cephalad and laterally, resulting in different injury patterns and altered clinical examination (Figure 12.4). The enlarging uterus compresses the inferior vena cava (IVC), reducing venous return and cardiac output (Figure 12.5). This, in turn, increases bleeding from injuries to the lower extremities. Compression of the IVC may be relieved by positioning the patient in the left lateral decubitus position. This may increase cardiac output by up to 30%. Other anatomical changes in advanced pregnancy include elevation of the diaphragms, which increase the risk of diaphragmatic injury in penetrating chest injuries and reduce the functional residual capacity (Figure 12.3, Figure 12.4, Figure 12.5).





Figure 12.3 At approximately 20 weeks, the uterine fundus can be palpated at the level of the umbilicus (red circle). The fetus is considered potentially viable when the uterus is palpable approximately 3 cm above the umbilicus (dotted red line).





Figure 12.4 As the uterus enlarges, intra-abdominal contents are displaced laterally and superiorly, causing changes in both physiology and clinical examination findings.





Figure 12.5 The gravid uterus compresses on the IVC when the mother is in the supine position. This can lead to decreased venous return and hypotension, exacerbated by blood loss. Left lateral decubitus positioning may improve compressive symptoms. Also visualized in this CT image is the lateral displacement of the colon by the gravid uterus.



Physiological Changes in Pregnancy


During pregnancy the respiratory system undergoes some changes, including an increased respiratory rate and decreased functional residual capacity, resulting in a mild respiratory alkalosis. Additionally, there is an increase in circulating blood volume with relative anemia preparing the maternal body for a significant blood loss at time of delivery. Blood pressure drops slightly during the second trimester, and the heart rate typically increases. Significant blood loss of up to 1,500–2,000 ml can occur before hypotension is measured. During blood loss, there is autotransfusion from the placenta to the mother, stabilizing the maternal hemodynamics but resulting in fetal hypoxia. Fetal oxygenation is maintained if maternal PaO2 is above 60–70 mmHg and is compromised below that level, resulting in fetal distress. For this reason, the best resuscitation for the fetus is the resuscitation of the mother.



Trauma Resuscitation


The basic principles of ATLS should be applied, having in mind the special anatomic and physiologic differences in pregnancy. The resuscitation team should include obstetrics and neonatology in all cases with a potentially viable fetus. Resuscitative efforts are guided by the needs of the mother, and maternal outcome is the strongest predictor of good fetal outcome.


The pregnant patient with a uterine fundus palpable at the umbilicus should immediately be placed in 25–30 degrees of left lateral decubitus, either by tilting the backboard if in spinal precautions or by placing rolled-up towels behind the patient’s right flank once the backboard has been removed. All patients should receive supplemental oxygen, irrespective of SaO2.


If a thoracostomy tube is required, it should be placed one to two intercostal spaces higher than the usual fourth to fifth intercostal space recommended for nonpregnant patients, due to the diaphragmatic elevation that occurs during pregnancy with increased abdominal contents.


If immediate blood transfusion is necessary before type-specific or cross-matched blood is available, O negative blood is the blood product of choice in order to avoid potential Rh sensitization of an Rh-negative mother. Massive transfusion protocol (MTP) should be initiated as needed. Vasopressors can further jeopardize placental perfusion due to their vasoconstrictor effect and should be avoided.


The abdominal and pelvic examination should include the level of the fundus of the uterus in order to estimate gestation. Abdominal tenderness to palpation or uterine tetany may be seen in placental abruption and fetal parts presenting through a ruptured uterine wall may be palpable as irregularities of the abdominal wall, mandating immediate surgical intervention. The presence of blood in the abdominal cavity does not always present as peritonitis, as signs of peritoneal irritation are muted in pregnancy. The presence of vaginal bleeding may be due to placenta abruption or vaginal tear, especially in patients with pelvic fractures. If there is significant bleeding, a digital exam with sterile gloves and speculum inspection is performed to determine the source of bleeding. Caution is taken to avoid accidental injury to the placenta and exacerbation of bleeding through a partially dilated cervix. If there is minimal bleeding, the vaginal exam may be deferred until placenta previa has been ruled out by ultrasound. In the absence of vaginal bleeding, the pelvic examination should be performed to evaluate for the pooling of amniotic fluid and to evaluate the presence and stage of active labor (cervical dilatation, effacement, and fetal station).

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Apr 22, 2021 | Posted by in EMERGENCY MEDICINE | Comments Off on Chapter 12 – Trauma in Pregnancy
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