Obstetric Trauma

Definition/Etiology:

Trauma occurs in 6-8% of pregnancies.  Top 3:

• Intimate partner violence (8.307/100,000 live births)
• MVC (207/100,000 live births)
• Falls (49/100,000 live births)

Pathophysiology:

• After 12 weeks gestation, the uterus begins to expand above the pelvis, and is more vulnerable.
• Uterine blood flow is as high as 600 mL/minute in the third trimester and not autoregulated, thus a decrease in maternal systolic blood pressure can cause a significant fall in blood flow, and in turn, fetal oxygenation.
• Cardiac output and heart rate go up during pregnancy.
• Temporary EKG changes and a new cardiac murmur are common during pregnancy.
• Plasma volume increases more than RBC volume during pregnancy, so this creates a dilutional drop in hemoglobin and hematocrit.

Clinical Presentation:

If uterine fundus is at or below the umbilicus, then <20 weeks.  If above, then >20 weeks.

22-23 weeks is the youngest considered viable.

Possible presentations due to trauma:

• Premature rupture of membranes
• Preterm labor
• Placental abruption 
• Miscarriage
• Fetal injury or death
• Maternal death
• All of the presentations of non-pregnant patients

If maternal hypovolemic shock, coma, exploratory laparotomy, then fetal death is at least 40-50%.

Collaborative Management:

Consult OB during resuscitation so they can help determine if emergency cesarean is indicated:

• To save the fetus (>24 weeks) in the setting of imminent maternal death or a fetal heart rate tracing predictive of fetal acidosis.
• Save the mother’s life if CPR has not been effective within four minutes, regardless of gestational age.

Liberal use of maternal oxygen supplementation.

The gravid uterus compresses the inferior vena cava when supine, and decreases the return of blood to the heart.  It’s important to tilt a spinal board 30 degrees if possible during resuscitation.

Monitor fetal heart rate.  Normal is 110-160 bpm.

Medications:

• Tetanus immunization is OK to give during pregnancy if a wound requires it.
• If mom is Rh-negative, she may need to receive anti-D immune globulin (RhoGam) because a fetomaternal infusion of blood can occur during trauma.
• All of the same medications in the preterm labor lecture.

Labs:

• Urine drug screen
• Rh-D 
• CBC, CMP, Coags

Imaging:

• Ultrasound / FAST exam
• MRI preferred since no radiation, but CT is faster.  Decision is case-by-case.

Evaluation | Patient Monitoring | Education:

ACOG recommends using seat belts and airbags.  Lap belt should go under uterus, and shoulder belt should go above uterus and between breasts.

• Continuous maternal NIBP, cardiac, and SaO2 monitoring
• Continuous fetal heart rate monitoring
• Liberal use of maternal oxygen supplementation
• Collaborate with L&D team

Linchpins: (Key Points)

• Liberal use of supplemental oxygen.

• Roll pregnant patient 30 degrees laterally to offset the uterus from the inferior vena cava.

• Normal fetal heart rate is 110-160 bpm.

• Call L&D team ASAP in case cesarean is needed.