Author:
KyleRoedersheimer
Bryant K.Allen
Description
- Fetal and maternal injury after the first trimester:
- Increased rate of fetal loss, but not maternal mortality
- Likelihood of fetal injury increases with the severity of maternal insult
- Physiologic hypervolemia of pregnancy may lead to an underestimation of blood loss:
- Clinical shock may be apparent only after a 30% maternal blood loss
- Abdominal findings are less evident in the gravid patient
- Minor trauma can also lead to fetal injuries (at least 50% of fetal losses)
- An Injury Severity Score (ISS) >9 is associated with a worse outcome
- 1 in 3 pregnant women admitted to the hospital for trauma will deliver during her hospitalization
- Less frequent bowel injury
- More frequent retroperitoneal hemorrhage due to the engorgement of pelvic organs and veins
- Increased morbidity and mortality with pelvic fractures due to pelvic and uterine engorgement
- Fetal or uterine trauma includes:
- Placental abruption
- Fetal-maternal hemorrhage (FMH)
- Premature labor
- Uterine contusion or rupture
- Fetal demise
- Premature membrane rupture
- Hypoxemic or anatomic fetal injury (skull fracture)
- Abruption occurs in up to 60% of severe trauma and 1-5% of minor injuries:
- Most common cause of isolated fetal death
- Accounts for up to 50% of fetal loss
- May occur with no external bleeding (20%)
- Occurs after 16 wk of gestation
- Can present with abdominal pain, cramping, and /or vaginal bleeding
- Hallmark is uterine contractions
- Uterine rupture:
- Usually in patients with prior C-section
- Nearly universal mortality
- 10% maternal mortality
- Pelvic fracture:
- May be an independent predictor of fetal death
- Fatal insults to fetus can occur in all trimesters
- 10% fetal mortality in patients with minor fractures
- FMH occurs in >30% of severe trauma:
- Isoimmunization of Rh-negative mothers can occur with as little as 0.03 cc of FMH
- Penetrating trauma results in direct injury to fetus, maternal shock, and premature delivery
- Fetal mortality is 73% and maternal mortality is 66% following penetrating trauma
- Falls and slips occur in 1 out of 4 pregnant women and may cause:
- 4.4-fold increase in preterm birth (PTB)
- 8-fold increase in placental abruption
- 2.1-fold increase in fetal distress
- 2.9-fold increase in fetal hypoxia
- Burns: If BSA involved is >40% the maternal and fetal mortality approaches 100%
- Intentional trauma and domestic violence (DV) increases the risk for PTB 2.7-fold and low birth weight 5.3-fold
- Risk factors for DV include substance abuse, low socioeconomic status, unintended pregnancy, history of DV prior to pregnancy, history of witnessed violence, and unmarried status
- Electrocution is a significant cause of fetal mortality
Etiology
- Trauma occurs in ∼7% of all pregnancies
- Just over half of trauma occurs in third trimester
- Mean maternal age ∼24 yr
- Nearly half (46.8%) of all injury hospitalizations involve woman younger than 25 yr of age
- There is a strong inverse relationship with maternal age and incidence of trauma
- Most common cause of nonobstetric morbidity and mortality in pregnancy
- Rate of fetal loss 3.4-38%
- Causes:
- Motor vehicle accidents (MVA; 48-84%)
- DV
- Falls
- Direct abdominal trauma
- Penetrating (stab or gunshot)
- Electrical injury or thermal burn
- Suicide
- Exposure to toxins
- Higher rate in younger woman
- Substance abuse is a common accompaniment of MVA and DV
Signs and Symptoms
History
- Mechanism of injury
- Last menstrual period
- Abdominal pain
- Uterine contraction
- Vaginal bleeding or leakage of fluid
- Previous pregnancies, C-sections
- Substance use/abuse
Physical Exam
- Perform with patient in left lateral recumbent position if possible
- Primary survey
- Secondary survey
- Tertiary survey
- Placental abruption:
- Uterine rupture:
- Uterine tenderness and variable shape
- Palpation of fetal body parts
- Determine the gestational age (EGA) to assess viability:
- Estimate last menstrual period
- EGA = fundal height (FH; distance from pubic bone to top of uterus in cm after week 16
- Vaginal exam to assess for:
- Blood
- Amniotic fluid
- Cervical dilation and effacement
Essential Workup
- Maintain spinal immobilization
- Identify maternal condition first:
- Airway management and resuscitate as indicated
- Determine the EGA to assess viability:
- EGA = FH after week 16
- Doppler fetal heart tones
- Sonography (may miss small abruptions)
- Fetal/maternal monitoring for >4-6 hr:
- Only monitor viable fetuses (typically with an EGA >24 wk)
- Abruption unlikely if no contractions during first 4 hr of monitoring
- >8 contractions/hr over 4 hr is associated with adverse outcome
- If >1 contraction every 10 min, there is a 20% incidence of abruption
- The occurrence of bradycardia, poor beat-to-beat variability, or type II “late” deceleration indicates fetal distress
- An abnormal tracing has a 62% sensitivity and 49% specificity for predicting adverse fetal outcomes
- A normal tracing combined with a normal physical exam has a negative predictive value of nearly 100%
Diagnostic Tests & Interpretation
Lab
- CBC, urinalysis
- Blood gas and electrolyte panel
- Type, Rh, and screening of blood
- The Kleihauer-Betke (KB) stain:
- Identifies FMH in vaginal fluid or blood
- Indicated when quantification of FMH is important
- Should be performed in all pregnant patients >12 wk gestation
Imaging
- Shield the uterus if possible, but obtain necessary maternal radiographs
- Inform the mother of the potential risks of radiation exposure
- No definite evidence of increased risk for congenital malformation or intrauterine death
- Cancer risk is debated
- Radiation <1 rad (10 mGy) believed to carry little risk
- Increased risk of fetal malformation at 5-10 rad
- The radiation exposure is estimated at the following:
- CXR (2 views): Minimal
- Pelvis (anteroposterior): 1 rad
- Cervical spine x-ray: Minimal
- Thoracic spine x-ray: Minimal
- Lumbar spine x-ray: 0.031-4.9 rads
- CT head: <0.05 rads
- CT thorax: 0.01-0.59 rads
- CT abdomen: 2.8-4.6 rads
- CT pelvis: 1.94-5 rads
- Ultrasonography:
- Focused assessment with sonography for trauma (FAST) exam
- Evaluate for solid-organ injury or hemoperitoneum
- Fetal heart activity
- Gestational age
- Amount of amniotic fluid (amniotic fluid index)
- Misses 50-80% of placental abruptions
- Test vaginal fluid with nitrazine paper (turns blue) and for ferning
- If present, likely rupture of membranes and presence of amniotic fluid
- With stable penetrating trauma, triple-contrast CT is advocated, particularly with stab wounds
Diagnostic Procedures/Surgery
As indicated by traumatic injury
Differential Diagnosis
Differential diagnosis is broad and should include careful exam for occult traumatic injuries
Prehospital
- Maintain spinal immobilization
- Patients in late second and third trimesters should be transported to a trauma center
- Advise trauma center early of pregnancy and EGA to facilitate mobilization of appropriate resources
- Place patient (while on backboard) in the left lateral recumbent position to avoid supine hypotension (after 20 wk EGA or earlier in multiple gestations)
- Mast suit inflation over the abdomen is contraindicated
Initial Stabilization/Therapy
- Direct therapy to the mother with no delays due to pregnancy:
- Manage airway and resuscitate as indicated
- Cardiac, pulse oximetry, and cardiotocographic monitoring
- Tilt patient or board 15-30° to the left (or manually displace uterus to the left)
- Many factors affect resuscitation in late pregnancy
- Increased ventilatory rate
- Increased oxygen demand
- Reduced chest compliance
- Reduced functional residual capacity
- Incompetent gastroesophageal sphincter
- Increased intragastric pressure
- Increased risk of regurgitation
ED Treatment/Procedures
- Lactated Ringer preferred for IV fluids:
- Large volumes of normal saline may induce hyperchloremic acidosis
- Replace estimated blood loss in a 3:1 ratio:
- O-negative packed red blood cells if type-specific blood is not available
- In cases of severe hemorrhage transfusion of fresh frozen plasma, platelets and packed RBC at 1:1:1 ratio lowers the rate of coagulopathy and may improve survival
- Resort to transfusions after 1 L of estimated blood loss or if hypovolemia persists after 2 L of crystalloid
- Nasogastric tube decompression (higher risk of aspiration in pregnancy)
- Foley catheterization to assess urinary output
- Tube thoracostomy:
- Use an intercostal 1-2 spaces higher to avoid diaphragm
- Rapid sequence intubation:
- Safe and preferred method
- Avoid aspiration and deoxygenation
- If diagnostic peritoneal lavage is necessary, use supraumbilical open technique
- Use tocolytic therapy only for hemodynamically stable patients:
- Contraindicated if cervix dilated >4 cm or if FMH and abruption have not been reasonably ruled out
- Use tocolytics only when >8 contractions/hr have lasted >4 hr
- A perimortem cesarean delivery may be attempted within 4-5 min of cardiopulmonary arrest
- 45% of fetuses and 72% of mothers survive C-section as a result of trauma
- When fetus delivered without FHTs, mortality approaches 100%
- In minor trauma after week 20, fetal and maternal monitoring is best done in the labor and delivery area
- If burns are >50% BSA + fetus in the second or third trimester consider delivery
- RhoGAM in all Rh-negative women (within 72 hr):
- 50 mcg IM in women <12 wk pregnant
- 300 mcg IM in women >12 wk pregnant
- 24 hr recheck for ongoing FMH:
- Tocolytics: Magnesium sulfate 4 g IV
- Avoid aspirin, hypnotics, nonsteroidals, vasopressors when possible
Disposition
Admission Criteria
- Vaginal bleeding or amniotic fluid leakage
- Fetal-maternal hemorrhage
- Abdominal pain
- Uterine contractions
- Evidence of fetal distress
- Abruption placenta
- Hemoperitoneum or visceral or solid-organ injury
- Fetal survival begins at week 24 (9.9%):
- Survival becomes significant after week 26 (54.7%)
Discharge Criteria
- All the following criteria must be met:
- No uterine contractions for >4 hr of tocodynamometry
- No evidence of fetal distress
- No vaginal bleeding or amniotic fluid leakage
- No abdominal pain or tenderness
- Timely obstetric follow-up
- Specific instructions to return if any of the above symptoms occur
- Discharge only in consultation with obstetrics
- Education on the proper use of seatbelts should be stressed prior to discharge if MVC related trauma
- Shoulder harness portion should be positioned over the collarbone between the women's breasts
- Lap belt portion under the pregnant abdomen as low as possible on the hips and across the upper thighs and not above or over the abdomen
Follow-up Recommendations
A pregnant trauma patient being discharged after appropriate evaluation and observation needs prompt follow-up with obstetrician
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