BACKGROUND AND PURPOSE:

• Mazza et al. (JAMA Network Open, 2022) examined the clinical, pregnancy, and delivery characteristics and maternal outcomes related to amniotic fluid embolism (AFE)

METHODS:

• Retrospective cohort study
• Population
  • Vaginal or cesarean deliveries from January 2016, to December 2019
  • Data obtained from the Healthcare Cost and Utilization Project’s National Inpatient Sample (NIS)
  • NIS represents hospital discharge data for more than 90% of the US population | Survey weights based on a random sampling of 20% of hospitalized patients annually
• Exposure
  • AFE
• Study design
  • The role of AFE on outcomes was assessed using a  logistic regression model
• Primary outcome
  • Clinical, pregnancy and delivery characteristics of AFE
  • Maternal mortality after AFE
• Secondary outcomes
  • Severe maternal morbidity indicators
  • Maternal mortality per clinical and pregnancy characteristics

RESULTS:

• 14,684,135 deliveries
  • Median age: 29 (IQR, 25 to 33 years)
• AFE diagnoses: 880
  • Incidence rate: 6.0 per 100,000 deliveries
• In the multivariable analysis the following factors were associated with AFE
  • Patient factors
    • Older age | Asian and Black race | Western US region | Pregestational hypertension | Asthma | Illicit substance use | Grand multiparity
  • Pregnancy factors
    • Placental accreta spectrum (PAS) | Placental abruption | Uterine rupture | Polyhydramnios | Chorioamnionitis | Preeclampsia | Fetal growth restriction | Fetal demise
  • Delivery factors
    • Early gestational age | Cervical ripening | Cesarean delivery | Operative delivery | Manual removal
• Among these, placental accreta spectrum had the largest association with AFE
  • Adjusted odds ratio (aOR) 10.01 (95% CI, 7.03 to 14.24)
• When stratified by the PAS subtypes, more severe forms of PAS had a greater association with AFE
  • Increta and percreta: aOR 17.35 (95% CI, 10.21 to 28.48)
  • Accreta: aOR 7.62 (95% CI, 4.8 to 12.01)
• Patients who had AFE were more likely to experience
  • Coagulopathy
    • aOR 24.68 (95% CI, 19.38 to 31.44)
  • Cardiac arrest
    • aOR 24.56 (95% CI, 17.84 to 33.81)
  • Adult respiratory distress syndrome
    • aOR 10.72 (95% CI, 8.09 to 14.20)
• The maternal mortality rate after AFE: 17.0%
• This rate exceeded 30% when AFE co-occurred with other severe maternal morbidity indicators
  • AFE, cardiac arrest, and coagulopathy: 45.8%
  • AFE, shock, and cardiac rhythm conversion: 43.2%
  • AFE, cardiac arrest, coagulopathy, and shock: 38.6%
• The maternal mortality rate also exceeded 30% when AFE occurred in the setting of placental pathology
  • AFE and PAS: 42.9%
  • AFE and placental abruption: 31.3%

CONCLUSION:

• In this population, AFE occurred in 6.0 of every 100,000 deliveries
• Risk factors associated with AFE were identified
  • Placenta accreta spectrum had the largest association with AFE
• Maternal mortality after AFE was high at 17.0%
  • This rate increased if AFE co-occurred with other maternal morbidity indicators or placental pathology
• The authors state

It is unknown whether adherence to the Society for Maternal-Fetal Medicine checklist for initial management of AFE is associated with improved maternal outcome

Other studies suggested the importance of high-quality cardiopulmonary resuscitation; correction of coagulopathy, including tranexamic acid use; and extracorporeal membrane oxygenation use for AFE management, but these procedures were not assessed in this study

Learn More – Primary Sources:

Association of Pregnancy Characteristics and Maternal Mortality With Amniotic Fluid Embolism

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