Trauma in Pregnancy

Trauma remains the leading cause of morbidity and mortality in pregnant women. It increases the risk of preterm delivery, placenta abruption, fetomaternal hemorrhage, and pregnancy loss. Motor Vehicle Accidents (MVAs) account for 70% of blunt abdominal trauma, then comes falls and direct assaults.

Evaluating and managing pregnant trauma patients requires knowing some physiological changes in pregnancy.

Physiological changes in pregnancy

Maternal blood volume increases at 10 weeks and reaches a peak level at 28 weeks (45%)
Mild anemia because of increased plasma volume (plasma > red blood cells)
Cardiac output increases by 1-1.5L/min at 10 weeks until the end of pregnancy
Heart rate increases by 10-20 beats/min at the 2nd trimester + decrease in the blood pressure (BP) by 10-15 mmHg. This explains the late deterioration in dropping BP; they may lose 30-40% of blood before signs of hypotension
Uterine blood flow = maternal mean arterial pressure
At 12 weeks, the uterus becomes an intra-abdominal organ, which is susceptible to direct injuries
The bladder becomes anterior
Gravid uterus causes stretching to the abdominal wall
At 18-20 weeks, an expanding mass of gravid uterus causes hypotension in the supine position by compressing the IVC. Avoid placing IV lines in the femoral/lower extremities.
Diaphragm elevated 4 cm, which makes the tidal volume increase by 40%, residual volume decreases by 25%, which causes the short apnea time in pregnant patients
Splenic injury is a common cause of hemorrhage

Important actions in pregnant trauma patients

Apply supplemental oxygen early because of compensation of hypoxia is limited
Consider early intubation
50% more fluids are needed for volume replacement
At 20 weeks, place wedge under the right hip, tilting to 30 degrees during the transfer on trauma board
Early nasogastric tube placement to avoid aspiration
Avoid pressors, which causes uteroplacental hypoperfusion

Rhogam (Rh immunoglobulin) and Tetanus Prophylaxis

Administer RhoD (Human Rho(D) immune globulin) to Rh-negative women; 50 mcg for <12 weeks, 300 mcg for >12 weeks. Tetanus prophylaxis is safe but considered as category C.

Images and Radiation Exposure

Do not withhold needed images. The greatest risk to fetal viability from ionizing radiation is within the first 2 weeks after conception and the highest malformation during the embryogenic organogenesis at 2-8 weeks. The risk of central nervous system teratogenesis is highest at 8-16 weeks. A dose of 5 rad is the threshold for human teratogenesis. Plain radiographs is <1 rad. Abdominal CT + Pelvic angio has the highest dose of rad (2.5-3.5). One of the critical problems is the abruption of the placenta, and CT is sensitive for abruption placenta, 86%, and has 98% specificity. The iodine contrast could cross the placenta and causing neonatal hypothyroidism.

Pelvic exam can be done only after performing an ultrasound to determine the placenta location and exclude placenta previa.

Special Tests

Vaginal fluid pH. If the pH is 7, it is amniotic fluid. If the pH is 5, it is vaginal secretions. Ferning on microscope slide = amniotic fluid.

APT ( alkali denaturation) test is qualitative evaluation to determine the presence of fetal Hg in maternal blood.

Kleihauer-Betke test measures fetal hemoglobin transfer to mothers’ blood.

Specific Issues

Direct fetal injuries

It is rare. It can be seen some injuries such as maternal pelvic fractures, direct trauma to the fetal skull.
Uterine rupture

It is less than 1%. It may be seen at late second and third trimester. It is associated with high fetal mortality. The palpation of fetal parts over the abdomen and radiological evidence of abnormal fetal location determine rupture.
Uterine rupture

It is less than 1%. It may be seen at late second and third trimester. It is associated with high fetal mortality. The palpation of fetal parts over the abdomen and radiological evidence of abnormal fetal location determine rupture.
Uterine irritability

The sign of the onset of preterm labor. Avoid using tocolytics; it causes tachycardia for both mother and fetus.
Placental abruption

1-5% from minor injuries, 40-50% of major injuries. Even simple falls can cause sudden fetal demise. Most sensitive clinical findings; uterine irritability, which can be explained by having more than 3 contractions per hour at the ED.

Fetal viability

The fetus will likely be viable at 24 weeks and above.
The normal fetal heart rate is 120-160 bpm. Heart rate below and above these limits is critical. Because ultrasound may not detect placenta abruption, nor rupture or fetal-placental injuries, high-suspicion and close monitorization are necessary.

Cardiotocography (CTG)

4-6 hours will be enough for most of the cases. Persistent contractions or uterine irritability needs an external CTG for 24 hrs. Fewer than 3 contractions per hour could indicate a safe discharge.

Indication for Emergency C-Section

Fetal tachycardia.
Lack of beat to beat on long term viability.
Late deceleration = fetal distress.

C-section has a 75% survival rate in 26 weeks or above. If the fetal heartbeats are present and the procedure was performed early, the success rate is higher.

References and Further Reading

Tintinalli, J., Stapczynski, J., Ma, O. J., Cline, D., Cydulka, R., & Meckler, G. (2010). Tintinalli’s emergency medicine: a comprehensive study guide: a comprehensive study guide. McGraw Hill Professional.

Cite this article as: AlHanouv AlQahtani, KSA, "Trauma in Pregnancy," in International Emergency Medicine Education Project, October 25, 2019, https://iem-student.org/2019/10/25/trauma-in-pregnancy/, date accessed: December 2, 2023