Amniotic fluid embolism

An amniotic fluid embolism (AFE) is a very uncommon childbirth (obstetric) emergency in which amniotic fluid enters the blood stream of the mother to trigger a serious reaction. This reaction then results in cardiorespiratory (heart and lung) collapse and massive bleeding (coagulopathy).[1][2][3] The rate at which it occurs is 1 instance per 20,000 births and it comprises 10% of all maternal deaths.

Amniotic fluid embolism
SpecialtyObstetrics 
Pathophysiology of the amniotic fluid embolism

Signs and symptoms

Amniotic fluid embolism is suspected when a woman giving birth experiences very sudden insufficient oxygen to body tissues, low blood pressure, and profuse bleeding due to defects in blood coagulation. Though symptoms and signs can be profound, they also can be entirely absent. There is much variation in how each instance progresses.[2]

Causes

AFE is very rare and complex. The disorder occurs during the last stages of labor when amniotic fluid enters the circulatory system of the mother via tears in the placental membrane or uterine vein rupture.[4] Upon later analysis, fetal cells are found in the maternal circulation. When the fetal cells and amniotic fluid enter the bloodstream, reactions occur that cause severe changes in the mechanisms that affect blood clotting. Disseminated intravascular coagulation occurs and results in serious bleeding. The condition can also develop after elective abortion, amniocentesis, cesarean delivery or trauma. Small lacerations in the lower reproductive tract are associated with AFE.[2]

According to one study, induction of labor may double the risk of AFE. However, other studies have refuted this claim. A maternal age of 35 years or older is associated with AFE.[5]

Diagnosis

AFE is diagnosed when all other causes have been excluded. The presence of fetal squamous cells or other fetal tissues, including meconium, have been found in the maternal circulation after the event. Diagnosis is also based upon the signs and symptoms observed during the birth or procedures.[2]

Treatment

Treatment is supportive. Since the circumstances that lead to this complication are difficult to influence, treatment to resolve the symptoms and deteriorating vascular conditions can improve outcomes.[2]

Epidemiology

Amniotic fluid embolism is very uncommon and the rate at which it occurs is 1 instance per 20,000 births. Though rare, it comprises 10% of all maternal deaths.[2]

History

This rare complication has been recorded seventeen times prior to 1950. It was first described in Brazil in the 1920s.[6]

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References
  1. Stafford, Irene; Sheffield, Jeanne (2007). "Amniotic Fluid Embolism". Obstetrics and Gynecology Clinics of North America. 34 (3): 545–553. doi:10.1016/j.ogc.2007.08.002. ISSN 0889-8545. PMID 17921014.[subscription required]
  2. Stein, Paul (2016). Pulmonary embolism. Chichester, West Sussex, UK Hoboken, NJ: John Wiley & Sons Inc. ISBN 9781119039099.
    • Leveno, Kenneth (2016). Williams manual of pregnancy complications. New York: McGraw-Hill Medical. pp. 223–224. ISBN 9780071765626.
  4. Vinay Kumar; Abul K. Abbas; Nelson Fausto; Jon C. Aster (2014-08-27). Robbins and Cotran Pathologic Basis of Disease, Professional Edition E-Book. Elsevier Health Sciences. pp. 129–. ISBN 978-0-323-29639-7.
  5. Kramer, M.S.; Rouleau, Jocelyn; Baskett, Thomas F; Joseph, KS (2006). "Amniotic-fluid embolism and medical induction of labour: a retrospective, population-based cohort study". The Lancet. 368 (9545): 1444–1448. doi:10.1016/S0140-6736(06)69607-4. PMID 17055946.
  6. Amniotic fluid embolus: An update. Alfredo Gei, Gary D. V. Hankins: Contemp Ob/Gyn 45 (2000)
Classification
External resources


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