Blunt trauma in pregnancy


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Blunt trauma in pregnancy

  2. 2. TOPICS Demographics Anatomy  Maternal Physiology Resuscitation and assessment Laboratory Evaluation Imaging Anesthesia in the Pregnant Patient injuries unique to the pregnant trauma patient
  3. 3. demographics  An estimated 5 to 8% of all pregnancies are complicated by trauma and it is the leading cause of non-obstetric maternal deaths  Maternal trauma is associated with significant fetal morbidity and mortality  Estimates of fetal death rates following trauma vary widely ranging from 5 to 60% of cases
  4. 4.  Risk factors associated with fetal loss include high maternal injury severity score and shock in the mother  maternal injury, both major and minor, have resulted in spontaneous abortion, premature labor, fetal hypoxia, fetal skull fractures, uterine rupture, placental abruption.
  5. 5.  The most common mechanism of maternal injury is motor vehicle crashes, accounting for approximately 55% of maternal trauma  Falls and physical abuse account for an additional 10 to 30% of injuries.  Motor vehicle crashes (MVC) have been shown to be the leading cause of fetal death related to maternal trauma;  an examination of fetal death certificates found that MVCs are responsible for 82% of fetal deaths associated with maternal trauma.
  6. 6. Anatomy Early in the gestational period, the fetus is well protected in the uterus which lies within the pelvis.  After the 12th week, the uterus begins to expand out of the pelvis and into the abdomen reaching the umbilicus at 20 weeks gestational age and the costal margin at 36 weeks.  In the final 4 weeks, the fetus descends into the pelvis and fundal height is lower.
  7. 7. Anatomy  As pregnancy advances, maternal organs are displaced upward and the diaphragm may be elevated as much as 4 cm from the nonpregnant state.  While the gravid uterus may provide a degree of protection to the maternal viscera, the fetus is at increased risk of direct injury as the pregnancy progresses.  In the third trimester, the uterine wall thins, the amount of amniotic fluid decreases, and the fetal head rotates down into the pelvis all of which place the fetus at increased risk for injury.  In particular, the location of the fetal head within the pelvis places the fetus at risk of skull fractures and traumatic brain injury secondary to maternal pelvic fractures.
  8. 8. Maternal Physiology  Pregnancy results in dramatic changes in maternal physiology affecting virtually every organ system.  Over the course of a normal pregnancy, there is an increase of maternal total body water of 5– 8 l.  The water content of the fetus, placenta, and amniotic fluid accounts for 3.5 l.  Maternal blood volume is expanded by approximately 1,500 mL,( plasma volume by 1,200 mL, and red blood cell volume by 300–400 mL.)  Because the plasma volume expands more than red blood cell mass, the result is a physiologic anemia of pregnancy
  9. 9. Maternal Physiology  The increased blood volume protects the mother from hemorrhage and hypotension.  As a result, the presence of hypotension in the pregnant patient indicates a significant volume loss and should be addressed promptly.  The vasculature of the placenta is dilated at baseline, but very responsive to catecholamines.  A decrease in maternal circulating volume and catecholamine release may result in a significant increase in uterine vascular resistance, diminished placental blood flow, and a reduction in fetal oxygenation even in the presence of normal maternal vital signs.  In fact, maternal volume loss may first be manifested as fetal distress
  10. 10. Maternal Physiology  Pregnancy results in profound changes in the cardiovascular system. Cardiac output is significantly increased in pregnancy by an average of 30 to 50% as compared to the nonpregnant state.  Cardiac output is the product of stroke volume and heart rate and both of these parameters are altered in pregnancy.  There is an initial rise in maternal heart rate (HR) at about 5 weeks; the HR continues to increase until about the 32nd week when it peaks at 15–20 beats per minute above the patient’s pregravid state.  Stroke volume begins to increase at 8 weeks and at 32 weeks it reaches a maximum value of 20 to 30% increase over pre-pregnant values.
  11. 11.  While cardiac output is increased in pregnancy, it is highly variable with respect to maternal position, particularly with advanced pregnancy.  In late pregnancy, the gravid uterus may completely occlude the vena cava when the patient is in the supine position, dramatically reducing venous return, stroke volume, and as a result, cardiac output.  Stroke volume and cardiac output are optimized when the pregnant patient is in the left lateral position with the knees brought toward the chest to alleviate the compression of the inferior vena cava.
  12. 12.  In addition to the increased red cell mass as noted above, there are other changes in the hematologic system in the pregnant patient.  The peripheral white blood cell count (WBC) rises throughout pregnancy. In the first trimester 5,000 to 10,000/mm3, second and third trimesters 5,600 to 12,200/mm3. In labor, 20,000 to 30,000/mm3  Additionally, changes occur to protect against peripartum hemorrhage the etiology of which is multifactorial Various procoagulants are increased There is also decreased activity in the fibrinolytic system. Consequently, pregnancy is a hypercoaguable state and the pregnant trauma patient is at increased risk for venous thromboembolic complications.
  13. 13. Maternal Physiology The respiratory system also undergoes a significant change in the course of pregnancy. The upper respiratory tract becomes hyperemic and edematous . Care should be taken when placing nasogastric tubes in pregnant patients to avoid excessive bleeding. The chest wall undergoes reconfiguration as the subcostal angle increases and the chest circumference expands by 5–7 cm. The level of the diaphragm rises 4 cm, decreasing the volume of the lungs in the resting state, reducing both total lung capacity and functional residual capacity (FRC).
  14. 14.  Pregnancy also is a state of chronic hyperventilation with a 30 to 40% increase in minute ventilation driven by an increase in tidal volume.  As a result, the arterial pCO2 is decreased. Whereas a normal pCO2 is generally considered to be 37–40 mmHg, in the pregnant patient the expected pCO2 is 27–32 mmHg creating a chronic respiratory alkalosis.  increased maternal excretion of bicarbonate lowers the serum bicarbonate levels to 18–21 meq/L and maintains the maternal pH between 7.4 and 7.45
  15. 15.  The decrease in maternal pCO2 results in a gradient between maternal and fetal CO2 that facilitates the transfer of CO2 from the fetal to maternal circulation for excretion.  It is of the utmost importance to avoid acidosis in the pregnant patient as maternal acidosis compromises fetal– maternal gas exchange.
  16. 16. Glucose metabolism is altered during pregnancy. The changes in carbohydrate metabolism result in fasting hypoglycemia, postprandial hyperglycemia, and hyperinsulinemia.  In the fasting state The constant demands of The fetal–placental unit for glucose results in early depletion of maternal glycogen stores with fasting and a rapid conversion from carbohydrate to fat utilization.  In the fed state, insulin resistance begins in the first trimester. In the normal pregnancy, the pancreas compensates with an exaggerated insulin response.
  17. 17.  If the patient has limited pancreatic reserve in the pre-pregnant state, then patient may not produce enough insulin to overcome the resistance resulting in gestational diabetes.  As the fetus is primarily dependent on maternal glucose, normal maternal glucose levels are critical for proper fetal development.  Hyperglycemia in the first trimester is associated with birth defects and in the third trimester with fetal macrosomia.  Normal blood glucose levels should be maintained in the pregnant trauma patient to optimize maternal–fetal outcome.
  18. 18. gastrointestinal tract  diminished lower esophageal sphincter pressure  reduced gastric tone and motility Consequently, the pregnant patient is at risk for aspiration and early gastric decompression should be considered, especially prior to intubating the injured pregnant patient.
  19. 19. initial resuscitation and assessment Maternal assessment  One of the leading causes of fetal demise following trauma is maternal demise.Therefore, the primary focus on the initial assessment must be the prompt evaluation and treatment of the mother following the guidelines as outlined in the American College of Surgeons on Trauma Advanced Trauma Life Support manual.  As a result of the anatomic and physiologic changes that occur during pregnancy, there are a few special considerations in the primary survey.  The decreased gastric motility places a pregnant woman at increased risk for aspiration and early gastric decompression is appropriate.
  20. 20.  Because the fetus is sensitive to maternal hypoxia, supplemental oxygen should be provided. Additional care should also be taken during intubation.  If rapid sequence intubation is employed, a lower dose of succinylcholine is required due to decreased pseudocholinesterase levels in pregnancy.  If a tube thoracostomy is required, it should be placed one or two intercostal spaces higher than in nonpregnant patients secondary to the diaphragm elevation.  It is especially helpful to use the sagittal thoracic ultrasound examination to identify the location of the diaphragm.
  21. 21.  Finally, compression of the vena cava by the gravid uterus and resultant hypotension can be minimized by either manually displacing the gravid uterus to the left or tilting the long spine board to the left.  A focused abdominal ultrasound examination should be performed to evaluate the mother for intraperitoneal hemorrhage.  A focused abdominal ultrasound in pregnant trauma patients has been found to detect intraperitoneal fluid with a sensitivity, specificity, and accuracy similar to that of nonpregnant patients.
  22. 22. FAST (Focused Assessment by Sonography in Trauma)
  23. 23. (Morison’s pouch) showing (A) normal (B) hemoperitone um, with fluid (blood) in Morison’s pouch (arrow) and anterior to the liver.
  24. 24. (A) normal image, and (B) image positive for fluid (blood) in the spleno- renal recess.
  25. 25. (A) normal bladder (B) Pelvis with bladder surrounded by hypoechogen ic fluid (blood).
  26. 26. Fetal Assessment  After maternal assessment is completed and all immediately lifethreatening issues addressed in the mother, it is appropriate to perform a fetal assessment  An estimated gestational age of 20–24 weeks should prompt uterine and fetal monitoring under the supervision of the obstetric service.  If the mother is unable to provide obstetric history, the fundal height can be used as an estimation of gestational age.  In general, if the fundus is at the level of the umbilicus, the gestational age is at least 20 weeks and it should be assumed that the pregnancy is viable until an obstetrician determines otherwise.
  27. 27.  Cardiotocographic monitoring should be initiated as soon as possible and preferably immediately following the secondary survey in all potentially viable pregnancies.  The monitoring should be in place for a minimum of 2–6 h and the duration of monitoring should be increased in all patients with abdominal pain, contractions, or significant maternal injury.
  28. 28.  Ideally, the obstetrician or maternal fetal medicine specialist will be involved early in the care of these patients and be present to perform the initial fetal assessment.  The fetal ultrasound examination should include fetal heart rate and position, assessment of gestational age, biophysical profile, fetal middle cerebral artery Doppler examination, and evaluation of the placenta for abruption.
  29. 29.  Normal fetal heart rate varies between 120 and 160 bpm; both fetal bradycardia and tachycardia may have great clinical importance.  It is important to note that ultrasound has a sensitivity of about 50% for placental abruption; however, the positive predictive value of the test is high.  If abruption is suspected and there is evidence of fetal compromise in a viable gestation, emergent operative delivery should be considered.
  30. 30. Secondary Survey  The secondary survey of the mother is then performed followed by definitive care of both maternal and fetal injuries.  In the pregnant patient , the secondary survey must include a vaginal examination to assess for cervical effacement and dilation, fetal position as well as for the presence of blood or amniotic fluid.  Vaginal bleeding is abnormal and may be a sign of labor, placental abruption, placenta previa, or uterine rupture.
  31. 31. Laboratory Evaluation  All laboratory studies routinely ordered in trauma patients should be obtained in the pregnant patient.  At a minimum this should include hemoglobin, hematocrit, coagulation profile including fibrinogen, and ABO type and cross-matching.  Patients with a significant mechanism of injury and hemodynamic instability should also have an arterial blood gas assessed.  In addition, the Kleihauer–Betke (KB) test should be obtained in all Rh-negative women to ascertain whether fetal blood has entered the maternal circulation.
  32. 32.  Any Rh-negative woman with a positive test should receive Rh-immune globulin. The initial dose is 300 μg followed by 300 μg for each 30mL of estimated fetomaternal transfusion.  Recent data have also suggested that the KB test is an accurate predictor of the risk of preterm labor following maternal trauma.  In a retrospective review, Meunch et al. found that a positive KB test was a sensitive way to detect preterm labor and conversely, a negative KB test excluded preterm labor.
  33. 33. Imaging  Imaging studies should be obtained in the pregnant patient for the same indications as they are performed in the nonpregnant patient.  While various adverse effects on the fetus including microcephaly and mental retardation have been noted with high-dose radiation, no increase in teratogenicity for a fetus exposed to less than 10-rad or 100-mGy of radiation has ever been documented.  The American College of Obstetricians and Gynecologists has published guidelines for imaging during pregnancy and state that a 5-rad or 50-mGy exposure is not associated with adverse fetal outcome.
  34. 34.  Shields such as a lead apron should always be employed when possible as they reduce the radiation exposure of the fetus by30%.  If the patient is severely injured and multiple imaging studies are anticipated, it may be reasonable to consult a radiation specialist to assist in planning.  Furthermore, a radiation dosimeter badge may be attached to the mother so that the radiation dose may be easily tracked.  This badge may be very helpful in those patients who are admitted to the intensive care unit and may need daily chest radiographs or other frequent studies.  Pregnancy alone, however, should not deter the physician from ordering necessary diagnostic and therapeutic tests.
  35. 35. Indications for Laparotomy  The indications for laparotomy in the pregnant trauma patient remain the same as for the nonpregnant trauma patient.  These include hypotension in the presence of intraperitoneal fluid detected on ultrasound, peritonitis, and failed nonoperative management of solid organ injury.  During laparotomy, the obstetrician should be present and if delivery of the fetus is anticipated, a neonatologist should also be immediately available as well as the resources to resuscitate the infant.
  36. 36. Anesthesia in the Pregnant Patient  As mentioned previously, the pregnant patient should be considered at high risk for aspiration. Intubation should be conducted by the anesthesiologist as expeditiously as possible using rapid sequence intubation with cricoid pressure.  Pregnancy alters the anatomy of the airway and the larynx is pushed anteriorly. The need to maintain inline cervical immobilization and friable, edematous oral, nasal and tracheal mucosa that is prone to bleeding may further complicate the intubation.
  37. 37.  Pregnant trauma patients should be considered to have “difficult” airways until proven otherwise and it is advisable to have a “difficult” airway cart equipped with a flexible fiberoptic bronchoscope in the room.  The trauma surgeon should be present during the induction of anesthesia to perform an emergent surgical airway if needed as the fetus is especially sensitive to hypoxia.  Once the patient is intubated, she should be slightly hyperventilated to a pH of 7.4–7.45 to mimic the normal physiology of pregnancy.
  38. 38.  Thiopental or etomidate are useful induction agents. Ketamine should be avoided as it causes increased uterine tone and decreased uteroplacental perfusion.  As noted previously, smaller doses of succinylcholine are required in pregnant patients. Both depolarizing and nondepolarizing neuromuscular blocking agents cross the placenta and can result in hypotonic and apneic infants for which the neonatal resuscitation team must be prepared.  If the patient can tolerate a volatile anesthetic, one should be used as these agents relax uterine smooth muscle and decrease circulating catecholamines thus improving uterine perfusion.
  39. 39. Technical Considerations  Following the induction of anesthesia, a fetal monitor should be placed by the obstetrician if indicated.  If the planned incision makes intraoperative monitoring of the fetus impossible, then, at a minimum, fetal heart rate should be measured immediately before and at the termination of the procedure.  A wedge should be placed under the patient ‘s right side to displace the uterus and avoid inferior vena cava compression  Laparotomy is carried out though a vertical midline incision in the standard fashion and all indicated procedures are performed.  If the uterus is found to be intact at laparotomy and the fetus is not in distress, intraoperative delivery is rarely indicated.  On rare occasion, intraoperative delivery may be indicated to expose and control nonobstetric-related hemorrhage in the mother.
  40. 40. injuries unique to the pregnant trauma patient Placental Abruption  The vast majority of fetal losses following blunt trauma to the abdomen are the result of placental abruption. Although the reported incidence of abruption in patients with minor injuries is 1 to 5%, it is estimated to occur in 40 to 50% of significant maternal trauma.  While the uterus has a great deal of elasticity, the placenta does not.  In blunt trauma, shearing forces occur at the uterine–placental interface resulting in separation of the placenta.  Patients present with vaginal bleeding, abdominal pain, uterine irritability as seen on fetal monitoring, shock, or fetal distress. It should be noted that abruption can occur in the absence of significant uterine bleeding.  The only treatment for a significant abruption is immediate delivery of the fetus.
  41. 41. Preterm Labor  There is about a 5% incidence of preterm labor following maternal trauma.  Labor is initiated following trauma by one of two mechanisms: either premature rupture of the membranes or destabilization of lysosomal enzymes resulting in prostaglandin production.  If the membranes are intact, tocolytic therapy should be considered if deemed appropriate by the treating obstetrician.
  42. 42. Uterine Rupture  Uterine rupture is a rare, catastrophic complication of blunt abdominal trauma.  The incidence is approximately 0.6% of cases of all blunt trauma during pregnancy.  Occurring primarily late in pregnancy, the fetal mortality approaches 100% with a maternal death rate of 10% from associated injuries.
  43. 43. Direct Fetal Injury  Direct fetal injury is very rare in blunt trauma complicating less than 1% of all significant maternal trauma. The maternal soft tissue, uterus, and amniotic fluid all provide a significant degree of protection to the fetus.  Those cases of direct fetal injury that do occur are usually late in the gestational period.  The most commonly reported direct fetal injury is head injury.
  44. 44.  If the head of the fetus is engaged in the pelvis, the fetus is at increased risk for brain and skull injuries. Even if the head is not engaged, the fetus is at risk for shearing injury to the brain.  Overall, pelvic fractures are the most common specific maternal injury resulting in fetal mortality.  Of note, pelvic fractures are not an absolute contraindication to vaginal delivery.  Women who have suffered a pelvic fracture are, however, more likely to require an operative delivery than women that have not suffered a pelvic fracture.  Severe traumatic fetal brain injury secondary to airbag deployment has also been reported.
  45. 45. Emergency Cesarean Section Indications for emergency operative delivery include  a potentially viable fetus by gestational age,  the presence of fetal heart tones,  maternal distress, or fetal distress. A multicenter study documented infant survival rate of 75% of potentially viable gestations that underwent emergent operative delivery. The obstetrician, if available, should be involved in the decision-making process.
  46. 46. Perimortem Section  Perimortem section should be considered in the case of maternal arrest with a potentially viable fetus.  Delay in recognition of fetal distress is a preventable cause of fetal demise.  The best fetal outcomes have been documented if the infant is delivered within 5 minutes of the cardiovascular collapse of the mother. This leaves very little time for decision making.
  47. 47.  Factors that should be considered include the estimated gestational age of the fetus and the resources available at the hospital.  A vertical midline incision should be used from the xiphoid to the pubic symphysis. The uterus is incised vertically and opened. The umbilical cord is clamped and cut and resuscitation of the neonate is initiated.  Maternal resuscitative efforts should be carried out simulataneously.
  48. 48. Fetal Outcome  About 80% of women who suffer trauma during their pregnancy are released from the hospital without requiring delivery of the fetus.  Several studies have been published that suggest that injuries during pregnancy are associated with increased risk of both maternal and fetal adverse outcomes at the time of eventual delivery.  These include prematurity, low birth weight, fetal distress, and requirement of transfusion at delivery.  The etiology for these adverse outcomes may be related to subclinical abruption at the time of trauma.
  49. 49. Other studies have contradicted this and suggested that in the absence of complications at the time immediately surrounding the trauma, there is no difference in pregnancy outcome between injured and noninjured patients.
  50. 50. if the pregnant trauma patient leaves the hospital undelivered, the trauma and sequalae should be directly communicated to the patient’s obstetrician to allow for additional assessment and care during the remainder of the pregnancy and delivery.
  51. 51. THANK YOU