Trauma and Pregnancy

While it is important to remember that there are two patients, the survival of the fetus is dependent on optimal management of the mother.

Airway

• Potentially difficult airway due to increased soft tissue edema, and breast enlargement may impede laryngoscopy — to facilitate intubation consider the use of:
  • a laryngoscope with a short or tilted handle.
  • a bougie.
  • video laryngoscopy.
• Cricothyroidotomy may be more difficult due to soft tissue changes.
• Aspiration risk is higher because of increased intrabdominal pressure and delayed gastric emptying — use cricoid pressure during intubation and decompress the stomach early.

Breathing

• Oxygenation
  • Administer high flow O2 until hypoxemia, hypovolemia and fetal distress are excluded.
  • Functional residual capacity (FRC) is decreased (because of increased intra-abdominal pressure). This predisposes to rapid desaturation as the lung is less effective as an oxygen reservoir. This is particularly important for rapid sequence intubation. Respiratory problems may require earlier intervention.
• Ventilation
  • Increased tidal volumes due to progesterone means hyperventilation is normal (PCO2 of 30 mmHg from the 2nd trimester), and HCO3 is normally low reflecting a compensated respiratory alkalosis.
  • Decreased thoracic compliance due to breast enlargement and increased intrabdominal pressure.
  • Bag-valve-mask ventilation is more difficult.
• Chest drains should be placed higher ( e.g. 3rd or 4th intercostal space) as the diaphragms may be up to 4 cm higher.

• Vital signs are alteredin pregnancy, mimicking early shock.
• Heart rate is increased 10-15/min from baseline by the third trimester.
• Blood pressure is 10-15 mmHg lower by the second trimester then increases to near normal by term.
• Cardiac output increases by 1-1.5 L/min by the end of the first trimester, due to increased blood volume and decreased systemic vascular resistance.
• CVP is lower due to decreased venous return.
• Fluid resuscitation
• uterine blood flow is not autoregulated, so it is best to err on the side of hyper-hydration as maternal compensation for blood loss will be at the expense of the fetus.
• Women with pre-eclampsia, in particular, are more prone to fluid overload.
• Hypotension and shock
• supine hypotension syndromefrom compression of the IVC by the uterus may occur
  • this may decrease cardiac output by 30% due to decreased venous return.
  • After 24 weeks, place a wedge under backboard to tilt 15 to 30 degrees to the left to avoid this.
• Evidence of hypovolemia may not be apparent until about 1500 mL of blood has been lost. This is because blood volume is increased by 50% during pregnancy (peaks and plateaus at about 34 weeks) resulting in a hematocrit of 30-35% (red cell production is also increased).
• shock may result in pituitary insufficiency as the pituitary gland enlarges by up to 50% and is more prone to infarction.

From Marx et al (2009) - click to enlarge

Fetal distress can occur even if the mother is stable and the maternal injury is apparently minor.

• Continuous fetal monitoring is required for at least 4-6 hours at >24 weeks gestation. This may be performed using cardiotocography (CTG), which is a useful predictor of outcome.
• Transplacental hemorrhage
• All Rhesus-negative mothers should be given 300 mcg of anti-D IgG within 72 hours of injury unless the trauma is trivial or distant from the uterus.
• The Kleihauer-Betke test can be performed but a negative test does not rule out clinically significant transplacental hemorrhage. As little as 0.01 mL of blood entering the maternal circulation will sensitise 70% of rhesus-negative women.

Obtain an obstetric consult early, whenever potential uterine or fetal problems are suspected. Fetal distress may necessitate emergency caesarean section, as may maternal deterioration (to save the mother).

• There is a predisposition to regurgitation and vomiting. This results from a decreased gastric emptying rate due to progesterone together with an increased intra-abdominal pressure. Consequently, there is an increased risk of aspiration.
• Early decompression with a nasogastric tube should be considered.
• Intrabdominal organs are displacedby the enlarged uterus.
• The intestines move cephalad and are relatively protected by the uterus.
• The position of the liver and spleen is largely unchanged.
• The bladder is an intra-abdominal organ after the 1st trimester.
• Injury to the uterus or vessels may lead to precipitous bleeding as there is ~1L/min blood flow to the uterus late in pregnancy.

• Hematological changes in pregnancy
• Relative anemia (Hct 30-35%) is normal in pregnancy due to increased blood volume.
• Leukocytosis is a normal feature of pregnancy.
• Normal coagulation profile except that fibrinogen and D-dimers are elevated.
• Blood transfusion needs to consider Rh status, and rhesus-negative women should receive Anti-D IgG.
• Autotransfusion may occur after delivery due to sequestration of blood in the placenta.

The pelvis is different.

• Interpretation of pelvic x-rays needs to account for widening of the pubic symphysis and sacroiliac joints that occurs by the 7th month of gestation.
• pelvic fractures can be associated with uterine injury or massive retroperitoneal hemorrhage due to injury to the enlarged uterine vessels.
• Pelvic binders may not fit pregnant patients.