Amniotic fluid embolism syndrome: Analysis of the Unites States International Registry

Abstract: Background Incidence, risk factors, and perinatal morbidity and mortality rates related to amniotic fluid embolism (AFE) remain a challenge to evaluate, given the presence of differing international diagnostic criteria, the lack of a gold standard diagnostic test, and a significant overlap with other causes of obstetrical morbidity and mortality. Objective The aims of this study were (1) to analyze the clinical features and outcomes of women using the largest United States-based contemporary international AFE registry and (2) to investigate differences in demographic and obstetrical variables, clinical presentation, and outcomes between women with typical vs atypical AFE, using previously published and validated criteria for the research reporting of AFE. Study Design The AFE Registry is an international database established at Baylor College of Medicine, (Houston, TX) in partnership with the Amniotic Fluid Embolism Foundation, (Vista, CA) and the Perinatology Research Branch of the Division of Intramural Research of the NICHD/NIH/DHHS (Detroit, MI). Charts submitted to the registry between August 2013 and September 2017 were reviewed, and cases were categorized into typical, atypical, non-AFE, and indeterminate, using the previously published and validated criteria for the research reporting of AFE. Demographic and clinical variables, as well as outcomes for patients with typical and atypical AFE, were recorded and compared. Student’s t tests, chi-square tests, and ANOVA tables were used to compare the groups, as appropriate, using SAS/STAT® software, version 9.4 (Cary, NC). Results One hundred and twenty-nine charts were available for review. Of these, 46% (59/129) represented typical AFE and 12% (15/129) atypical AFE, 21% (27/129) were non-AFE cases with a clear alternative diagnosis, and 22% (28/129) had an uncertain diagnosis. Of the 27 women misclassified as an AFE with an alternative diagnosis, the most common actual diagnosis was hypovolemic shock secondary to postpartum hemorrhage. Ten percent (6/59) of women with typical AFE had a pregnancy complicated by placenta previa and 8% (5/61) had undergone in vitro fertilization to achieve pregnancy. Sixty-six percent (49/74) of women with AFE reported a history of atopy or latex, medication or food allergy compared to 34% of the obstetrical population delivered at our hospital over the study period (p = Conclusion Our data represent a series of women with AFE whose diagnosis has been validated by detailed chart review, using recently published and validated criteria for research reporting of AFE. Although no definitive risk factors were identified, a high rate of placenta previa, reported allergy, and conceptions achieved through in vitro fertilization was observed.