Amniotic Fluid Embolism (AFE): A Review of the Literature Orientated on Two Clinical Presentations—Typical and Atypical

Background/Aim: Recently, a comparative study on the incidence of AFE has highlighted rather confusing results, showing that the complication is more than three times higher in North America than that in some European countries. In this paper, we put forward the hypothesis that this discrepancy is due to inaccurate diagnosis of non-classical form of AFE (atypical AFE). We also provide an outline of symptoms that characterize this type of AFE based on the analysis of all available case reports. Material and Methods: We searched Medline from 1969 (its inception) to 2011, using the key words “amniotic fluid embolism”. The search produced 1127 articles, including 208 case reports of AFE and other publications identified as eligible for our study (11 review articles and 6 population-based studies of the last few years). Moreover, we looked through the articles from the period before “inception of Medline” to find 178 earlier case reports. Full texts were analyzed. Results and Conclusions: (i) Worldwide, 447 cases of AFE have been reported, including 70 cases of atypical AFE (15.7%). (ii) Typical AFE is characterized by three clinical phases (cardiopulmonary collapse, clotting disorders and hemorrhages, multiorgan disturbances), whereas the atypical one shows lack of cardiopulmonary collapse as the initial presentation—the first to appear is obstetric hemorrhage and/or pulmonary and renal dysfunction. (iii) Four subclasses of atypical AFE were distinguished on the basis of case reports: uterine hemorrhage-type of AFE, ARDS as the only presentation of atypical AFE, paradoxical AFE, and cesarean sectionrelated atypical AFEs.