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Trauma in pregnancy is a much more complex topic than simply, ’tilt them on their side’. Trauma in the obstetric patient is a leading cause of non-obstetric mortality.

The complexity of the obstetric trauma scenario relates to:

  1. Alterations in maternal anatomy and physiology
  2. The sensitivity of the foetus to hypotension and hypoxia.
  3. Issues of radiation exposure
  4. Rh isoimmunisation
  5. Placental abruption
  6. Preterm labour


A 32 year old woman who is 24 weeks pregnant is brought into the emergency department by ambulance. She was a passenger in a high speed motor vehicle accident. She has no other relevant past history. She has sustained a head injury, with a small scalp laceration and has right lateral chest wall tenderness to palpation. There is an obvious tibial abnormality.

This patient needs to be assessed in the same way as a non-trauma patient. However the details of some of the assessment and management will change depending whether the patient is:

  1. not pregnant
  2. <22 weeks pregnant
  3. >22 weeks pregnant

The time of pregnancy is all about a viable fetus. This age changes depending on institution. For the purposes of this blog we will use greater than 22 weeks as a viable gestational age. There is no argument that greater than 26 weeks is viable.

If we are unsure of the patient status, remember that all female patients of child bearing age, should be considered to be pregnant unless proven otherwise. Investigation should be with a urine pregnancy test or blood bhCG. History alone is not reliable in determining pregnancy, as the rate of incidental pregnancy in those that are found to be pregnant is about 11%(1).


Airway / Breathing

There are some important points in respect to airway and breathing in the obstetric patient.

  1. The foetus is very sensitive to hypoxia, so adequate oxygenation is paramount ie saturations should be kept at > 95%.
  2. The maternal respiratory tract becomes oedematous
  3. There is a decrease in the functional residual capacity.
    • This begins in the second trimester and can be as much as 20%
  4. There is an increase in oxygen requirements, with an increase in basal oxygen consumption.
  5. Failed intubations are 8 times more likely(2)
    • Use a smaller tube size
    • Intubate early
  6. There is an increased risk of regurgitation ( consider placing a NGT)
    • There is delayed gastric emptying
    • There is compression of the upper GIT
  7. If a chest tube is needed aim to insert 1-2 intercostal spaces higher(3)
    • The diaphragm rises by approximately 4cm
    • The chest diameter increases
    • This all results in an increased substernal angle


Fluid and blood should be given as for any other trauma patient.

If the patient is >22 weeks gestation, initiate fatal heart rate monitoring as early as possible. This should be cardiotocography(CTG), so that the uterine contractions and fetal heart rate can be monitored.

Specific things to consider in the obstetric trauma patient:

  1. The heart rate increases by about 15% in pregnancy
  2. There is an increase in blood volume in pregnancy, so tachycardia and hypotension may not appear early(4)
  3. Vena cava compression can decrease cardiac output by 30%(5). Therefore from mid-pregnancy onwards tilt the patient.
  4. Administration of vasopressors in trauma is controversial and an area of great interest at present, in the general trauma literature. In the obstetric trauma patient, pressors should be given as an absolute last resort, because placental perfusion can be detrimentally affected, secondary to utero-placental vasculature being very sensitive to pressor effects(6).
  5. Fetal heart rate monitoring is important, as maternal vital signs may be preserved, whilst utero-placental perfusion is impaired(7). Fetal heart rate monitoring can help us detect and act on fatal hypoxaemic injury early.

Fetal Heart Rate Monitoring: How long to monitor for.

This is a controversial area. It is agreed that a minimum of 4 hours of CTG monitoring is needed. This may be sufficient for minor trauma such as falls(8,9), where it has been found that at 4 hours, if uterine contractions have ceased, especially after minor injury then the patient can be taken off monitoring. For more significant trauma, 24 – 48 hours of monitoring is needed(10).

Fatal Heart Rate Monitoring: What are we looking for?

CTG monitoring gives us information on:

  1. Uterine Activity(contractions)
    • These are a common finding, occurring in about 40% of trauma cases. Most resolve with no adverse fetal effects.
    • The basal uterine tone and the frequency and intensity of contractions is important
  2. Fetal Heart Rate
    • Compromised fetal perfusion and oxygenation presents with abnormal fetal heart rate(11)
    • The absolute rate is important ie both bradycardia or tachycardias
    • Deceleration patterns are also important as is
    • Loss of variability.

Blood Products in pregnancy

When giving blood products, give O-ve blood, to avoid Rh sensitisation in the Rh -ve patient.

Fetal-maternal haemorrhage occurs in about 30% of pregnant trauma patients. It is rarely massive, but when it is, there is a high rate of fetal mortality(12). Most fetal-maternal haemorrhage is small and subclinical, as only 0.001mL of fetal blood is needed for sensitisation of a Rh -ve mother.

Anti-D IgG should be given to all Rh-ve mothers, within the first 72 hours(13).



The traditional physical examination of the abdomen, may not help in ruling out suspected abdominal injury(14). However, any tenderness over the uterus, may suggest placental abruption. It can also be associated with vaginal bleeding and pre-term labour. Most placental abruptions occur in the first few hours after injury and almost all within the first 24 hours.(15,16). They may occur following relatively minor injury and are the most common cause of fetal death in blunt trauma. When severe, rapid caesarean section is necessary.

If there is vaginal bleeding in obstetric trauma with a viable fetus, no speculum or vaginal examination should be performed without prior ultrasound, as we need to rule out a placenta previa.

Ultrasound is very sensitive at detecting placenta previa, but not as good in detecting placental abruption. CTG is the investigation of choice for detecting abruption.

Beware physical irregularities in the abdomen, as these may represent fetal parts outside the uterus in a uterine rupture. Uterine rupture is rare in trauma and presents as an irregular uterine contour, abdominal distension and maternal shock. Fetal mortality is 100%.

Direct fetal injury is rare in blunt trauma, occurring in <1% of cases. It can occur in deceleration injury, but tends to be in the form of fetal skull fracture secondary to maternal pelvic fracture(17).


After mid-pregnancy, the rate of mortality and visceral injury is lower in the obstetric patient than in the general population, due to the cushioning effect of the uterus.



Injuries here, will depend on the mechanism involved. Deceleration injuries can cause direct fetal trauma.

The protective devices used in vehicles, can also be a source of injury:

  1. Seat belts worn incorrectly ie over the abdomen, can cause direct abdominal injury
  2. Air bags have been associated with uterine rupture and placental abruption.

Falls occur quite commonly. They are associated with significant maternal or fetal complications in less than 10% of cases(18).

These patients all require fetal heart rate monitoring as the injuries that can occur include:

  • placental abruption
  • placental rupture
  • preterm labour
  • fetal mortality

This is not an uncommon injury. The literature reports a high fetal mortality, mostly because amniotic fluid is a good conductor(19). The risk factors for adverse outcomes include:

  1. Magnitude of the current
  2. Pathway of the current: Beware a vertical current path ie., hand to foot as this will pass through the uterus.



There are a few differences in the laboratory results involved in pregnancy

  • The white cell count is elevated as a physiological response to pregnancy.
  • Fibrinogen levels are usually > 4g/L
  • D-dimer is often positive in pregnancy
  • CO2 is usually decreased in pregnancy ie 27-32mmHg
  • Creatinine levels decrease in pregnancy
  • ALP is secreted by the placenta, so levels may be twice as high.



All maternal trauma will need an ultrasound done. It is a good investigation for determining:

  • Gestational age
  • Presence of placenta previa
  • Amniotic fluid volume
  • Fetal injury

This is one of the most misunderstood and feared areas of investigations in obstetric trauma. The two areas that cause the controversy are teratogenicity and carcinogenic effects.


The highest teratogenic potential is during organogenesis at 5-10 weeks gestation. At a fetal age greater than 10 weeks, large radiation doses can produce CNS and grown retardation effects.


This is a greatly disputed area. Some studies say that there is no increased risk, whilst others say there is an increased risk at < 8 weeks gestation, even with minor exposure.(20,21)


Fetal exposure from routine imaging is low. Cummulative  exposure of > 5-10 rads is associated with an increased risk of fatal malformation. Exposure of < 5 rads gives an additional lifetime carcinogenic effect of <2% above the background lifetime risk of about 40%(22,23).

The exposure from basic X-rays is as follows(24):

  • CXR 0.005 rad
  • Pelvic X-ray is approximately 0.4 rad
  • CT brain 0.05 rad,
  • CT upper abdomen  3.0 rad
  • CT lower abdomen 3.0 to 9.0 rad
  • CT abdomen 3.5 rad.

If imaging is needed, it should be done. Beware that it is done properly, so it does not need to be repeated. There may be variation between machines and centres. The abdomen should be shielded as often as possible.

Watch the Video


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Peter Kas


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