What is the appropriate management for a 34-week pregnant woman involved in a motor vehicle accident with airbag deployment?

Management of a Pregnant Woman at 34 Weeks After Motor Vehicle Accident with Airbag Deployment

All pregnant trauma patients at 34 weeks gestation with a viable fetus require immediate transfer to a maternity facility (labor and delivery unit) for continuous electronic fetal monitoring for at least 4 hours, with extended 24-hour observation if any adverse factors develop, regardless of apparent injury severity. 1

Immediate Priorities at Scene/Emergency Department

Maternal Stabilization (Always First Priority)

• Maternal assessment and stabilization takes absolute precedence over fetal assessment at this gestational age, as maternal survival is essential for fetal survival 1
• Position the patient with left lateral uterine displacement (manual displacement or 15-30 degree left tilt) to prevent supine hypotensive syndrome from inferior vena cava compression by the gravid uterus 2, 1
• Maintain maternal oxygen saturation >95% with supplemental oxygen to ensure adequate fetal oxygenation 1
• Establish two large-bore (14-16 gauge) IV lines for fluid resuscitation 1
• Insert nasogastric tube if semiconscious or unconscious to prevent aspiration 1

Critical Initial Assessment

• Assume pregnancy in any reproductive-age female with significant injuries until proven otherwise 1
• Assess for life-threatening injuries using standard trauma protocols without modification for pregnancy 2, 1
• Do NOT defer or delay indicated radiographic studies (including abdominal CT) due to fetal radiation concerns—maternal benefit outweighs fetal risk 1

Specific Concerns with Airbag Deployment

Risk Stratification

• Airbag deployment does NOT appear to significantly increase placental abruption risk compared to crashes without deployment, with only 1 of 30 cases (3.3%) experiencing abruption in one series 3
• However, 73% of pregnant women experience uterine contractions after MVC with airbag deployment, and 53% sustain abdominal injury despite lower overall injury severity scores 4, 3
• Fetal brain injury can occur even with minimal maternal trauma and normal initial fetal assessment, as airbag forces may be transmitted to the fetus 5, 6

Key Clinical Pitfall

• Currently accepted fetal assessment methods may initially fail to detect catastrophic fetal brain injury following maternal trauma, with definitive evidence sometimes not appearing until weeks later 6
• Normal cardiotocographic monitoring and biophysical profile do not exclude significant fetal injury in the acute setting 6

Mandatory Laboratory and Diagnostic Studies

Maternal Blood Work

• Complete blood count, type and screen
• Coagulation panel including fibrinogen level (fibrinogen <200 mg/dL is an adverse factor requiring 24-hour admission) 1
• Kleihauer-Betke test (or equivalent quantification of fetomaternal hemorrhage) in all Rh-negative patients to determine additional anti-D immunoglobulin dosing 1

Imaging Studies

• Focused Assessment with Sonography for Trauma (FAST) to detect intraperitoneal bleeding 1
• Abdominal CT if intra-abdominal bleeding suspected (preferred over diagnostic peritoneal lavage in pregnancy) 1
• Obstetrical ultrasound to assess fetal viability, gestational age confirmation, amniotic fluid volume, and placental location (though ultrasound is NOT sensitive for placental abruption diagnosis) 1

Fetal Monitoring Requirements

Minimum Monitoring Duration

• All pregnant patients ≥23 weeks require continuous electronic fetal monitoring for at least 4 hours 1
• At 34 weeks gestation, this patient meets criteria for extended monitoring

Indications for 24-Hour Admission and Observation

The following adverse factors mandate 24-hour inpatient observation 1:

• Uterine tenderness or significant abdominal pain
• Vaginal bleeding
• Sustained uterine contractions (>1 contraction per 10 minutes)
• Rupture of membranes
• Atypical or abnormal fetal heart rate pattern
• High-risk mechanism of injury (airbag deployment qualifies)
• Serum fibrinogen <200 mg/dL

Given airbag deployment, this patient automatically qualifies for 24-hour admission regardless of other findings. 1

Rh Immunoprophylaxis

Universal Administration

• Administer 300 mcg anti-D immunoglobulin to all Rh-negative pregnant trauma patients within 72 hours of injury 1
• Perform Kleihauer-Betke test to quantify fetomaternal hemorrhage and determine if additional doses needed (10 mcg per mL fetal blood detected) 1

Management of Specific Complications

Placental Abruption

• Do NOT delay management waiting for ultrasound confirmation, as ultrasound has poor sensitivity for abruption 1
• Clinical diagnosis based on: vaginal bleeding, abdominal pain, uterine tenderness, contractions, abnormal fetal heart rate pattern, coagulopathy
• Immediate delivery indicated if fetal compromise or maternal instability present 1

Uterine Contractions

• Most common complication (73% with airbag deployment) 3
• Persistent contractions (>1 per 10 minutes) require 24-hour observation 1
• Consider tocolysis only if preterm labor diagnosed and no contraindications exist

Fetal Compromise

• Abnormal fetal heart rate patterns occurred in 20% of airbag deployment cases 3
• At 34 weeks, delivery should be considered for persistent non-reassuring fetal status, as neonatal outcomes are favorable at this gestational age 2

Delivery Considerations

Timing

• At 34 weeks gestation, immediate delivery is NOT routinely indicated unless maternal instability or fetal compromise exists 1
• If stable after 24-hour observation, continue pregnancy with close outpatient follow-up
• Corticosteroids for fetal lung maturity are NOT needed at 34 weeks unless emergency delivery anticipated 2

Mode of Delivery

• Vaginal delivery is preferred unless obstetric indications for cesarean section exist 2, 1
• Cesarean section indicated for: maternal hemodynamic instability, ongoing hemorrhage requiring laparotomy, or non-reassuring fetal status unresponsive to resuscitation 1

Perimortem Cesarean Section

• If maternal cardiac arrest occurs, perform cesarean delivery within 4 minutes to aid maternal resuscitation and fetal salvage at this viable gestational age 2, 1

Discharge Criteria and Follow-up

Before Discharge

• Obstetrical ultrasound must be performed on all admitted patients prior to discharge 1
• Minimum 24 hours of monitoring completed without adverse events
• No ongoing contractions, vaginal bleeding, or abnormal fetal heart rate patterns
• Normal coagulation studies

Outpatient Management

• Close obstetric follow-up within 1 week
• Counsel on warning signs: vaginal bleeding, decreased fetal movement, abdominal pain, contractions, fluid leakage
• Repeat ultrasound at 2-4 weeks to reassess for delayed complications, as fetal brain injury may not be immediately apparent 6

Special Considerations

Domestic Violence Screening

• Every woman sustaining trauma must be questioned specifically about intimate partner violence in a private setting 1
• Document findings carefully for potential legal purposes 1

Seatbelt Counseling

• Emphasize proper seatbelt use at all times: lap belt below the uterus across hips, shoulder belt between breasts and to side of uterus 1
• Current evidence is insufficient to recommend disabling airbags for pregnant women 1

Pain Management

• Acetaminophen 975 mg every 8 hours is first-line for pain control 7
• Ibuprofen 600 mg every 6 hours can be used postpartum but should be avoided during pregnancy after 28 weeks 7
• Short-course opioids (morphine preferred) only if severe pain uncontrolled by non-opioid options 7