BACKGROUND AND PURPOSE:

• SMFM and the Amniotic Fluid Embolism Foundation AFE Criteria
  • Sudden onset of cardiorespiratory arrest, or both hypotension (systolic blood pressure: < 90 mmHg) and respiratory insufficiency (dyspnea, cyanosis or peripheral capillary oxygen saturation < 90%)
  • DIC based on modified ISTH score >3
    • Platelets count: > 100,000/mL = 0 | < 100,000/mL = 1 | < 50,000/ mL = 2
    • Prolonged PT or INR: <25% increase = 0 | 25-50% increase = 1 | >50% increase = 2
    • Fibrinogen level: > 2 g/L = 0 | < 2 g/L = 1
  • Absence of fever (38 °C)
  • Onset during labor or within 30 minutes of delivery
• Previous studies performed using data derived from registries demonstrated that all 4 criteria were not always present in cases highly suspicious for AFE
• Ponzio-Klijanienkoa et al. (Journal of Gynecology Obstetrics and Human Reproduction, 2020) describe the first study to look at criteria in a population based-cohort  

METHODS:

• Retrospective study (2006 to 2018)
  • Maternity unit in France
• Participants
  • All patients strongly suspected of having AFE
• Study design 
  • Suspicion of AFE
    • AFE clearly stated in chart
    • Positive biological tests (IGFBP-1 [protein found in amniotic fluid] dosage in blood and/or in bronchoalveolar lavage and presence of amniotic and fetal cells in the bronchoalveolar lavage) or
    • Autopsy in favor of an AFE diagnosis
• Primary outcomes
  • Incidence rate of AFE
  • Presence of each of the 4 diagnostic criteria

RESULTS:

• 54,140 women delivered during time frame of study
  • Strongly suspected of having AFE: 0.03%: 14 women
  • 25.9/100,000 deliveries (95% CI, 12.3 to 39.5/100,000)
• Diagnostic criteria evaluation
  • Patients with all 4 criteria: 43% (6 of 14)
• Criteria
  • Hemodynamic collapse: 100% (all 14 patients)
    • Respiratory symptoms: 43% (6 patients)
  • DIC (ISTH criteria): 71% (10 patients)
    • All patients had clinical coagulopathy (subjective impression of clinician including “excessive blood fluidity and absence of clotting) and a massive PPH (rapid blood loss of >1000 mL)
  • Absence of fever: 79% (11 patients) | 3 women with fever but no signs of sepsis
  • Onset during labor or within 30 minutes of delivery: 100% (all 14 patients)
  • All patients presented with ominous, premonitory symptoms prior to onset of AFE, including neurological disorders or irreversible fetal bradycardia
  • 1 maternal death (autopsy confirmed AFE)
• Confirmation of AFE based on study protocol
  • Bronchoalveolar lavage containing amniotic and fetal cells: 4 patients
  • Increased plasmatic concentration of IGFBP-1: 10 patients

CONCLUSION:

• <50% of patients with a strong suspicion of AFE fulfilled all 4 AFE criteria
• Although all patients had a clinical diagnosis of coagulopathy, they did not always meet the modified ISTH score | Other scoring systems may be better suited for use in AFE
• Low grade fever is not unusual during labor (e.g., use of epidural)
• The authors suggest that premonitory signs are recognized by other professional organizations (e.g., United Kingdom Obstetric Surveillance System) and could be included in the AFE definition criteria such as

Neurological signs (seizure, confusion, agitation, fainting or anxiety and imminent death feeling), abnormal fetal heart rate, respiratory signs (dyspnea, cough, shortness of breath), and atypical signs (nausea and/or vomiting, arterial blood hypertension, skin rash, thoracic or abdominal pain)

Learn More – Primary Sources:

Evaluation of The 4 Diagnosis Criteria Proposed By The SMFM And The AFE Foundation For Amniotic Fluid Embolism In A Monocentric Population

SMFM: Amniotic fluid embolism: diagnosis and management

Related ObG Topics:

Peripartum Cardiomyopathy: Definitions, Diagnosis and Management

Pregnancy-Related Deaths in the U.S.: How Many are Preventable?

Results of the SALVO Trial: Cell Salvage During Cesarean Section