Trauma in Pregnancy
Jessica FJ Hughes Kisicki, MD
Emergency Medicine Resident
St. John Hospital and Medical Center
Trauma is the leading cause of non-obstetric related morbidity and mortality
during pregnancy. The most common cause of blunt and penetrating trauma in
pregnancy is motor vehicle crashes and gunshot wounds, respectively. While
management of pregnant patients involved in trauma is similar to non-pregnant
patients, there are key differences involved in resuscitation.
Specific complications that can occur in pregnancy-related trauma are placental
abruption, preterm labor, uterine rupture, direct fetal injury, and fetal
maternal hemorrhage. Placental abruption occurs in up to fifty percent of major
trauma. Signs and symptoms include abdominal pain, vaginal bleeding, and tetanic
uterine contractions. Placental abruption is the second most common cause of
fetal death and a major cause of maternal morbidity and mortality, possibly
triggering DIC or amniotic fluid embolism.
External fetal monitoring shows more than eight contractions per hour during the
first four hours of monitoring when placental abruption is present.
Placental abruption may require immediate fetal delivery. Uterine rupture occurs
in up to one percent of pregnancy-related trauma, and is more common in the late
second and third trimester. It is caused by a forceful impact directly on the
uterus, resulting in loss of uterine contour, palpation of fetal parts, and/or
radiologic evidence of abnormal fetal location. The maternal mortality due to
uterine rupture is close to ten percent, while the fetal mortality approaches
one hundred percent and requires immediate delivery of the fetus. Pregnancy
related trauma can also trigger preterm labor demonstrated by contractions and
cervical dilation. In addition, the fetus itself can experience direct injury.
Due to the protection of the pelvis, injury to the fetus is rare in the first
trimester. Most cases of fetal injury occur later in pregnancy and involve
fractures to the maternal pelvis when the fetal head is engaged, resulting in
injury to the fetal skull and brain. If the uterus is penetrated during trauma,
the chance of direct fetal injury is high. Lastly, fetal maternal hemorrhage can
complicate over thirty percent of major traumas, occurring when fetal blood
enters maternal circulation. This is most concerning if the mother is Rh
negative because it can cause maternal sensitization and isoimmunization to Rh
factor, resulting in problems with future pregnancies. Fetal maternal hemorrhage
can also cause fetal hypovolemia, anemia, distress, and even death.
The most common cause of fetal death is maternal death. Initial resuscitative
efforts must be directed at maternal stabilization prior to any evaluation of
the fetus. Initial trauma resuscitation of a pregnant patient is the same as
resuscitation of non-pregnant patients, with the following caveats. All pregnant
patients at least 18 weeks gestation should be tilted thirty degrees to the left
in order to prevent uterine compression of the inferior vena cava and
hypotension. An increase in maternal blood volume during pregnancy can result in
a loss of 35% of maternal blood volume before signs of hypotension are present.
During loss of maternal blood volume, the uterine arteries constrict resulting
in decreased fetal blood flow and oxygenation leading to fetal distress.
Therefore, it is crucial to adequately resuscitate the mother even if there are
no signs of hypotension initially. It is also important to recognize that 600 mL/min
of maternal blood flow goes to the uterus and, if injured, can result in severe
maternal hemorrhage. Next, during pregnancy there is a compensatory increase in
ventilation resulting in a respiratory alkalosis. This leads to an impaired
ability of pregnant patients to compensate adequately to respiratory compromise,
so intubation and respiratory support need to be considered early. Due to
changes in location of abdominal organs, there is an increased chance of complex
bowel injuries in trauma and there is delayed gastric emptying leading to the
potential for reflux and subsequent aspiration.
Early gastric decompression should be considered early. Lastly, vasopressor
agents cause impaired uterine blood flow resulting in diminished fetal blood
flow, and should only be used as a last resort.
In addition to the usual trauma labs, blood should be sent for blood type, Rh
status, and a DIC panel (PT, APTT, fibrinogen, platelet count and D-dimer
assay). The gestational age should be assessed by dates and by palpating the
uterus. At 12 weeks, the fundus should be at the pubic symphysis and at 20
weeks, the fundus will be at the umbilicus. The uterus should also be palpated
for tenderness or contractions. A sterile pelvic exam should be performed if
abdominal or pelvic trauma is suspected. Any lesions, vaginal bleeding, or
rupture of membranes needs to be identified. If fetal maternal hemorrhage is
suspected, Rh immune globulin must be given to all Rh negative patients within
72 hours. One dosing of Rh immune globulin is 50 ug for gestation 12 weeks or
less and 300 ug for gestation 13 weeks or more.
Tetanus prophylaxis should be given to all pregnant patients involved in trauma.
Next, any diagnostic imaging that is appropriate for maternal treatment should
be undertaken. Radiation exposure to the fetus can be minimized by shielding the
abdomen and pelvis. The indications for DPL and laparotomy are unchanged in
pregnancy and can these can be undertaken with minimal risk to the fetus.
Lastly, after maternal stabilization, fetal assessment should take place.
Fetal heart tones should be 120-160 beats per minute and can be assessed with a
stethoscope, Doppler, or ultrasound. A bedside ultrasound should be used to
evaluate the fetal condition. If gestation age is 20 weeks or beyond, external
fetal monitoring should be initiated at the earliest time after maternal
stabilization. Signs of fetal distress on external monitoring include fetal
tachycardia, lack of heart rate variability, late heart rate decelerations and
may be an indication for emergent c-section. External fetal monitoring should
take place for a minimum of 4 hours. If there are
3-7 uterine contractions per hour or persistent uterine irritability within the
first 4 hours, the patient should have monitoring extended to a minimum of 24
hours. If there are less than 3 contractions per hour in the first 4 hours, then
the patient can be safely discharged in conjunction with an OB evaluation.
If gestation age is at least 23 weeks and there is loss of maternal vital signs
during resuscitation, a perimortem c-section should be undertaken within five
minutes of maternal death. Studies have shown a fetal survival rate of up to 75%
if gestation is at or greater than 26 weeks, fetal heart tones are present, and
the procedure is performed at the earliest signs of fetal distress.
OB should be consulted at the earliest stage of fetal viability, between 15-20
weeks depending on the institution. After the minimum observation of mother and
fetus, the patient may be discharged or admitted to the trauma or obstetric
service. Pregnant patients involved in trauma can safely discharged if they have
adequate OB follow-up, and should be educated that they must return to a doctor
if they experience abdominal pain, cramping, vaginal bleeding, leakage of fluid,
or diminished fetal activity.
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Posted: Sunday, July 5, 2009