Tackling Trauma: Pearls for the Pregnant Patient
Trauma - we see some version of trauma every shift. We know trauma; we have an approach to it, a rhythm. But the rhythm changes when your trauma patient is pregnant. Imagine EMS calling this in:
“We have an approximately 30-year-old pregnant female - unclear how far along she is. She was the restrained driver in a high-speed motor vehicle collision. Heart rate 110, respirations 22, BP 108/58, O2 sat 99%. 5 minutes out.”
Nervous? Don’t worry. There’s some overlap here with the regular trauma evaluation, but pregnancy does involve some additional nuance. Remember, the best fetal resuscitation is maternal resuscitation.
What is the epidemiology of trauma in the pregnant patient?
Trauma is the most common cause of non-obstetric maternal death in the United States; it complicates 1 in 12 pregnancies. The most common mechanism in these patients is BLUNT TRAUMA, via:
Motor vehicle accidents
Falls (the combination of an altered center of gravity, lightheadedness from a baseline respiratory alkalosis, and laxity of the pelvic ligaments doesn’t bode well)
Intimate partner violence (which accounts for 25% of these cases. As a side note, injury prevention is paramount in pregnancy. Always ask about intimate partner violence.)
Pregnancy masks (and predisposes your patient to) badness
Understanding trauma in pregnancy is largely a matter of understanding the anatomy and physiology of pregnancy. The pregnant patient experiences increased intravascular volume, cardiac output (by up to 40% in the third trimester), and heart rate (by up to 10-15 bpm in the third trimester). She also has decreased systemic vascular resistance; both the systolic and diastolic pressures may drop by 10 mm Hg. The increased plasma volume relative to red blood cell expansion creates a dilutional anemia. This patient can lose 30% of her volume before her vitals reflect it. Do not be reassured by normal-ish vital signs. In the second trimester and beyond, the waters become murkier as the uterus moves out of the pelvis. Both the uterus and the bladder become more vulnerable to blunt injury simply due to their positions. As the uterus enlarges, it causes aortocaval compression, decreasing venous return and, in turn, impairing cardiac output. It also pushes upward toward the thoracic cavity, decreasing functional residual capacity and making oxygenation more difficult.
With that in mind, let’s return to our case...
How do you prep?
Call for help. Call OB/GYN, NICU, anesthesia, trauma...rally the troops based on your hospital’s resources. You’re about to receive not one, but two patients, so you need teams for both of them.
The familiar mantra: IV (labs), O2, monitor…+/- Rhogam
Obtain access above the diaphragm - place an IO if need be. Your patient’s venous return is compromised, and you need your meds/fluids/blood to circulate.
Labs must include blood type, Rh status, and a full coagulation profile including fibrinogen. This patient’s fibrinogen is decreased at baseline; a normal fibrinogen may mean she is already moving into DIC.
In the Rh-negative patient, we must also consider Rhogam which can be given up to 72 hours after the trauma. Feto-maternal hemorrhage complicates up to 30% of pregnant trauma cases. In patients up to 12 weeks’ gestation, give 50 mcg (which covers 5 cc of bleeding); in those beyond 12 weeks or with over 30 cc of bleeding, give 300 mcg. Some argue that we should give 300 mcg empirically in these cases, where we may not have accurate information rapidly about gestational age and/or the amount of feto-maternal hemorrhage. What about the Kleihauer-Betke test, you ask? In real life, a negative test does not exclude the diagnosis. Exercise caution.
Expect a difficult airway. Increased circulating progesterone increases total body water, which creates an edematous airway with friable mucosa. Additionally, the combination of decreased lower esophageal sphincter tone, decreased gut motility, delayed gastric emptying, and a gravid uterus pushing upward creates the perfect scenario for emesis and aspiration.
How to approach this: pre-oxygenate well, but be cautious with positive-pressure ventilation; consider sitting your patient upright. When using the bag-valve-mask, use low volumes and go slowly to avoid insufflating the stomach. Have smaller backup endotracheal tubes and multiple suction setups ready.
This patient will desaturate faster than usual due to increased oxygen demand, decreased reserve secondary to the uterus pushing upward, and increased minute ventilation. A normal pCO2 in a pregnant patient is 30.
How to approach this: ventilate faster than usual to avoid acidosis, aiming for an O2 saturation of 94% (which is best for both mom and the fetus). If you need to place a chest tube, aim one or two rib spaces higher than you normally would to avoid intra-abdominal placement.
Understand the concept of aortocaval compression. Remember that your vital signs may be misleading.
How to approach this: tilt the patient onto her left side (15-30 degrees) or have someone manually displace the uterus. Your choice of method depends on the logistics of the resuscitation - for example, it’s easier to do compressions in the second scenario. Use crystalloid liberally and have a low threshold to transfuse blood products.
Disability and Exposure - these evaluations are similar to those in a non-pregnant patient.
The Secondary Survey: additional nuances to consider
When examining the uterus, estimate the gestational age using fundal height. Inspect it for tenderness to palpation, contour, contractions, and palpable fetal parts. Uterine rupture is a real concern. Remember, too, that placental abruption can be complete, partial, or concealed.
Consider a sterile speculum exam to inspect for perineal/vaginal lacerations, urethral injury, ruptured membranes, status of the cervical os (open or closed), and possible fetal presentation. But remember, this exam is contraindicated in the third-trimester patient with vaginal bleeding.
Assess the fetal heart rate (normal is 120-160 bpm). Hopefully the OB/GYN team is setting up external fetal monitoring by now.
Speaking of imaging...
In this patient, your FAST is less sensitive since 1) it’s harder to obtain adequate windows, and 2) the gravid uterus compresses the paracolic gutters, changing how fluid flows in the peritoneum.
How to approach this: don’t be afraid to get CTs. I repeat: if the mechanism is significant or you suspect serious traumatic injury, don’t be afraid to order CTs. Contrast is a category B drug, and gadolinium is a category C drug. With regard to radiation, the American College of Radiology has stated that doses of less than 50 micrograys are not associated with increased rates of fetal anomaly or loss. A pan-CT (i.e. CT head, cervical spine, chest, abdomen, and pelvis) uses 25.2 micrograys. The American College of Obstetrics and Gynecology recommends limiting exposure to less than 50 micrograys throughout pregnancy. So while this is a large chunk of the “allowable” radiation, and does put the fetus at an increased risk of childhood and lifelong cancer, consider the risk/benefit ratio for the patient in front of you.
The resuscitative hysterotomy (previously known as the perimortem C-section) is a last-ditch effort. Consider this in the pregnant patient at 24 weeks gestation or later (i.e. fundus at the umbilicus or higher) who had a witnessed loss of pulses. The first incision should be made as soon as possible after (but ideally within four minutes of) loss of pulses; the procedure should be completed within 5 minutes. Act quickly and decisively; this is not the time for dainty cuts. The best outcomes are associated with procedure completion within five minutes, but neonatal survival has been reported after delays as great as thirty minutes. Your goal: give mom the best chance at ROSC (and possibly also deliver a viable neonate).
In terms of supplies, you don’t need much - just a scalpel and OR scissors to begin. In the meantime, send someone to grab a few clamps and sterile towels. Use the scalpel to make a large vertical incision from xiphoid to pubis. Cut down to the peritoneal wall and then through the peritoneum. Identify and deliver the uterus. Cut through the lower uterine segment vertically as well, taking care to avoid the fetus. Use scissors to extend this incision upward to the fundus, placing your non-dominant hand underneath the scissors to guard the fetus. Deliver the baby, clamp and cut the cord, and hand it off. Lastly, pack the uterus and abdomen with sterile packing or towels and resume your resuscitation.
A word on resuscitation medications in pregnancy
Safe medications include: the tetanus booster, most antibiotics (with the exception of fluoroquinolones and gentamicin), rapid-sequence intubation medications, propofol, and heparin.
Medications to avoid include: NSAIDs (since they can compromise uterine blood flow), narcotics (unless delivery is imminent), and antiepileptics (except in critical cases such as status epilepticus).
The best fetal resuscitation is maternal resuscitation.
Do not be reassured by normal-ish vital signs.
Remember to displace the uterus.
Expect and prepare for a difficult airway.
Know the resources available to you.
Sonika Raj is a current second year resident at Stony Brook Emergency Medicine.
Imaging of Trauma in the Pregnant Patient. Raptis et al, Radiographics 34(3): 748, May-Jun 2014
Edited by Ashley Mogul, MD