Trauma and Pregnancy Redux

Fetal injury is more likely in a motor vehicle crash if the lap-belt is incorrectly placed across the uterus rather than across the thighs.

Trauma affects up to 7% of pregnancies (only a minority require hospitalisation).

Specific injuries

• traumatic brain injury and hemorrhagic shock are the most common mechanisms of death.
• liver injury, spleen injury, and retroperitoneal hemorrhage are all more common.
• bowel injury is less common due to protection by the uterus.

Uterine injury

• assaults of pregnant women tend to target the uterus.
• uterine injury may coexist with pelvic fractures.
• Uterine injury is rare in blunt trauma (e.g. uterine rupture, placental abruption) but carries the risk of premature labour.  Direct fetal injury occurs in less than 1% of blunt trauma.
• In penetrating trauma, the uterus tends to protect other organs, but fetal mortality is much higher.

Always consider the possibility of domestic violence in the pregnant trauma patient.

• If an investigation is needed to optimise the management of the mother it should be performed as usual.
• Use imaging modalities that are free of ionising radiation whenever feasible and appropriate (especially ultrasound).

Consequences of radiation exposure from imaging are unlikely to be significant in most situations, but there is greater potential for harm in the first trimester.

• <5 rad has not been associated with an increase in fetal anomalies or pregnancy loss and can be considered ‘safe‘ at any stage of pregnancy.
• More than 5-10 rad is potentially risky, and is associated with an increased risk of childhood cancer even in the later stages of pregnancy.

Radiation exposure varies with different types of imaging, different equipment and different imaging protocols. In general, radiation exposure to the mother (not necessarily the fetus) for different types of imaging is:

• Chest XR ~ 0.5 rad to the lungs, and very little to a shielded abdomen.
• pelvic XR ~ 1 rad
• abdominopelvic CT ~ 5-10 rad.

But the estimated fetal exposure for various radiographic studies is considerably lower:

• Radiographs
  • Cervical spine XR 0.002 rad
  • Chest (two view) XR 0.00007 rad
  • Pelvis XR 0.040 rad
  • Thoracic spine XR 0.009 rad
  • Lumbosacral spine XR 0.359 rad

• CT scans (10 mm slices)
  • Head CT <0.050 rad
  • Chest CT <0.100 rad
  • Abdomen CT 2.60 rad

However it is worth consulting a radiologist to calculate estimated fetal dose when multiple diagnostic X-rays or CT scans need to be performed.

[Apologies for the old fashioned use of the rad, which seems to be prevalent in medicine — 100 rad is equivalent to 1 Gray.]

Continuous fetal monitoring is required for at least 4-6 hours at >24 weeks gestation. Before 24 weeks the fetus is pre-viable, and monitor will not alter the outcome.

Cardiotocography (CTG) should be used, as it is a useful predictor of outcome.

Continuous monitoring and further evaluation by an obstetrician is required if any of the following is present:

• uterine contractions
• non-reassuring fetal heart rate pattern
• vaginal bleeding
• significant uterine tenderness or irritability
• serious maternal injury
• rupture of the amniotic membranes

Emergency caesarean section may be required.

Activate Trauma Call and notify the on-call Obstetrician.

An approach to the management of the pregnant trauma patient:

• Primary survey and resuscitation
  • ABCs with C-spine precautions
• Determine if >24 weeks pregnant(uterus should be palpable above the umbilicus, which is reached at ~20 weeks)
  • if <24 weeks, then ‘ignore pregnancy’ and treat the mother according to your standard approach (no obstetric interventions will alter the outcome of a pre-viable fetus)
  • if>24 weeks, tilt backboard 15-30 degrees to the left to prevent supine hypotension syndrome
• Perform secondary survey (including PV exam and assessment of the uterus) and commence CTG monitoring.
  • if the mother is unstable
    • resuscitate and treat cause
  • if the mother arrests:
    • perform peri-mortem caesarean section in the ED, starting within 4 minutes of arrest ideally, if fetal heart tones detectable. Fetal survival has been reported at >20 minutes, but neurological outcome is partly determined by time to delivery post-maternal arrest.
    • If there are no fetal heart tones detectable, peri-mortem caesarean section may be considered in the hope of facilitating resuscitation of the mother. Otherwise it may be appropriate to stop resuscitation.
  • if the mother is stable, or stabilises with resuscitation
    • if CTG is stable then continue CTG monitoring for at least 4-6 hours.
• if CTG shows distress then obtain an emergency ultrasound and consider emergency Caesarean section.

Consider Rhesus status and Anti-D IgG in all pregnant patients >12 weeks gestation.

• Cusick SS, Tibbles CD. Trauma in pregnancy. Emerg Med Clin North Am. 2007 Aug;25(3):861-72, xi. PMID: 17826221.
• Marx JA, Hockberger R, Walls RM. Rosen’s Emergency Medicine: Concepts and Clinical Practice, 7th edition (2009) Mosby, Inc. [mdconsult.com]
• Resus.ME — EAST Guidelines on Trauma in Pregnancy.