Serendipitous signs, symptoms, laboratory parameters, and instrumental patterns of amniotic fluid embolism. Lessons from an analysis of case reports

OBJECTIVE: To investigate if serendipitous signs, symptoms, and laboratory and instrumental data described in cases of amniotic fluid embolism (AFE) were associated with more typical AFEs and better prognoses. STUDY DESIGN: Wide analysis of the case reports on AFE published from 1990 to 2014. A scoring system for quantifying the relevance was attributed to each sign, symptom, laboratory parameter, and instrumental abnormal pattern in AFE cases. Principal component rotated factor analysis was used to reduce data. The residual signs, symptoms, and laboratory and instrumental parameters were introduced in a multivariable logistic regression model (dependent variable: survival). RESULTS: AFE, clinically, has at least 2 serendipitous symptoms (restlessness and confusion, at rates between 10–15%) and a serendipitous laboratory parameter (rise in C-reactive protein blood levels, between 2–3%). Fatal AFE cases relate mostly to the severity of cardiac and pulmonary impairment, rather than with restlessness, confusion, and rise in C-reactive protein. CONCLUSION: The hypothesis that AFE has atypical behavior should be retained; the extent to which serendipitous findings of AFE relate to AFE outcomes is uncertain.