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    Amniotic Fluid Embolism

    Critical Care / Resuscitation, Pregnancy

    Last Updated Jun 08, 2022
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    By Julian Marsden, William Howling


    • Amniotic fluid embolism (AFE) is an obstetric emergency of uncertain etiology, rapid onset, varying symptoms, and high fatality rate.
    • The ‘classic’ AFE triad consists of hypoxia, hypotension, and coagulopathy.
    • Most commonly a woman in labor or shortly after vaginal or caesarean delivery sustains acute dyspnea, desaturation, followed by sudden cardiovascular collapse. Commonly followed by cardiac arrest, coagulopathy, or both.
    • No direct relation to either amniotic fluid or an embolism. The pathophysiology remains unclear, but is thought to be related to the entry of fetal antigens to maternal circulation which subsequently trigger an abnormal host response by activation of endogenous proinflammatory mediators.
    • Both unpredictable and unpreventable with no identified demographic or clinical risk factor.
    • Reported maternal mortality rate ranges from 20-60% depending on case inclusion criteria, with higher rates corresponding to more ‘classic’ presentations. Neonatal outcome mostly depends on maternal status, with fetal distress being common and mortality rates approaching 40% being reported.


    Diagnostic Process

    • The ‘classic’ AFE triad:
      • Hypoxia
      • Hypotension
      • Coagulopathy
    • Sudden onset during or immediately after labour.
    • There are many atypical manifestations of AFE.
    • At the present time AFE remains a clinical diagnosis and a diagnosis of exclusion.
      • coagulopathy caused by (rather than the cause of) excessive bleeding, myocardial infarction, and other conditions can all resemble AFE.

    Recommended Treatment

    Treatment is primarily supportive and based on observable pathophysiology.

    Quality Of Evidence?


    The outlined approach to initial acute management of AFE is largely informed by the clinical opinions of those with experience in critical care obstetrics.


    Related Information

    Reference List

    1. Clark SL. Amniotic fluid embolism. Obstetrics & Gynecology. 2014;123(2):337-348. doi:10.1097/aog.0000000000000107

    2. Clark SL, Romero R, Dildy GA, et al. Proposed diagnostic criteria for the case definition of amniotic fluid embolism in research studies. American Journal of Obstetrics and Gynecology. 2016;215(4):408-412.

    3. Combs CA, Montgomery DM, Toner LE, Dildy GA. Society for Maternal-Fetal Medicine Special Statement: Checklist for initial management of amniotic fluid embolism. American Journal of Obstetrics and Gynecology. 2021;224(4):B29-B32. doi:10.1016/j.ajog.2021.01.001

    4. Fitzpatrick KE, van den Akker T, Bloemenkamp KW, et al. Risk factors, management, and outcomes of amniotic fluid embolism: A multicountry, population-based cohort and nested case-control study. PLOS Medicine. 2019;16(11). doi:10.1371/journal.pmed.1002962

    5. Funk M, Damron A, Bandi V, Aagaard K, Szigeti R, Clark S. Pulmonary vascular obstruction by squamous cells is not involved in amniotic fluid embolism. American Journal of Obstetrics and Gynecology. 2018;218(4):460-461. doi:10.1016/j.ajog.2017.12.225

    6. Lisonkova S, Kramer MS. Amniotic fluid embolism: A puzzling and dangerous obstetric problem. PLOS Medicine. 2019;16(11). doi:10.1371/journal.pmed.1002976

    7. McDonnell NJ, Percival V, Paech MJ. Amniotic fluid embolism: A leading cause of maternal death yet still a medical conundrum. International Journal of Obstetric Anesthesia. 2013;22(4):329-336. doi:10.1016/j.ijoa.2013.08.004

    8. Pacheco LD, Clark SL, Klassen M, Hankins GDV. Amniotic fluid embolism: Principles of early clinical management. American Journal of Obstetrics and Gynecology. 2020;222(1):48-52. doi:10.1016/j.ajog.2019.07.036

    9. Pacheco LD, Saade G, Hankins GDV, Clark SL. Amniotic fluid embolism: diagnosis and management. American Journal of Obstetrics and Gynecology. 2016;215(2). doi:10.1016/j.ajog.2016.03.012

    10. Salhi BA, Nagrani S. Chapter 178: Acute Complications of Pregnancy. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. Ninth edition. Elsevier; 2017:2247-2248.

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