Amniotic fluid embolism

She was pushing. Now she is grey, she cannot get her breath, she says she is going to die — and thirty seconds later there is no pulse. The blood in the drape will not clot. That whole sequence took less than two minutes, and nothing in her history predicted it. This is the emergency that punishes the registrar who wants a diagnosis before a plan.^[3][11]

Overview — what it actually is

Forget the name. Nothing is embolising in the mechanical sense, and the pulmonary vessels are not physically plugged the way they are in a saddle thromboembolus.^[3][13]

What happens instead: fetal material crosses into the maternal circulation, and in a very small number of susceptible women it triggers a violent humoral and immune response. The clinical picture that follows looks far more like anaphylaxis than like a clot — which is why Clark's older label, the anaphylactoid syndrome of pregnancy, is still the most useful three words in the topic.^[3][11][12]

Two consequences follow, and both are examinable: ^[2][1]

• There is no confirmatory test. Fetal squames in maternal pulmonary blood are found in women without AFE and missed in women with it. Tryptase and complement are research tools.^[1][14]
• The diagnosis is made clinically, at the bedside, by exclusion. You will be asked to justify that phrase — say it deliberately, then say what you excluded.^[1][2]

References19ShowHide

1. [1]Pacheco LD, Saade G, Hankins GD, Clark SL Amniotic fluid embolism: diagnosis and management Am J Obstet Gynecol, 2016.PMID 26987420
2. [2]Clark SL, Romero R, Dildy GA, et al. Proposed diagnostic criteria for the case definition of amniotic fluid embolism in research studies Am J Obstet Gynecol, 2016.PMID 27372270
3. [3]Clark SL Amniotic fluid embolism Obstet Gynecol, 2014.PMID 24402585
4. [4]Fitzpatrick KE, Tuffnell D, Kurinczuk JJ, Knight M Incidence, risk factors, management and outcomes of amniotic-fluid embolism: a population-based cohort and nested case-control study BJOG, 2016.PMID 25683758
5. [5]Fitzpatrick KE, van den Akker T, Bloemenkamp KWM, et al. Risk factors, management, and outcomes of amniotic fluid embolism: A multicountry, population-based cohort and nested case-control study PLoS Med, 2019.PMID 31714909
6. [6]Knight M, Tuffnell D, Brocklehurst P, Spark P, Kurinczuk JJ Incidence and risk factors for amniotic-fluid embolism Obstet Gynecol, 2010.PMID 20410762
7. [7]Stafford IA, Moaddab A, Dildy GA, et al. Amniotic fluid embolism syndrome: analysis of the Unites States International Registry Am J Obstet Gynecol MFM, 2020.PMID 33345954
8. [8]Combs CA, Montgomery DM, Toner LE, Dildy GA Society for Maternal-Fetal Medicine Special Statement: Checklist for initial management of amniotic fluid embolism Am J Obstet Gynecol, 2021.PMID 33417901
9. [9]Pacheco LD, Clark SL, Klassen M, Hankins GDV Amniotic fluid embolism: principles of early clinical management Am J Obstet Gynecol, 2020.PMID 31376394
10. [10]Bonnet MP, Zlotnik D, Saucedo M, Chassard D, Bouvier-Colle MH, Deneux-Tharaux C Maternal Death Due to Amniotic Fluid Embolism: A National Study in France Anesth Analg, 2018.PMID 28961562
11. [11]Shamshirsaz AA, Clark SL Amniotic Fluid Embolism Obstet Gynecol Clin North Am, 2016.PMID 27816160
12. [12]Kanayama N, Tamura N Amniotic fluid embolism: pathophysiology and new strategies for management J Obstet Gynaecol Res, 2014.PMID 24888909
13. [13]Tamura N, Farhana M, Oda T, Itoh H, Kanayama N Amniotic fluid embolism: Pathophysiology from the perspective of pathology J Obstet Gynaecol Res, 2017.PMID 28188959
14. [14]Benson MD, Kobayashi H, Silver RK, Oi H, Greenberger PA, Terao T Immunologic studies in presumed amniotic fluid embolism Obstet Gynecol, 2001.PMID 11275019
15. [15]Leighton BL, Wall MH, Lockhart EM, Phillips LE, Zatta AJ Use of recombinant factor VIIa in patients with amniotic fluid embolism: a systematic review of case reports Anesthesiology, 2011.PMID 21720243
16. [16]Erez O, Mastrolia SA, Thachil J Disseminated intravascular coagulation in pregnancy: insights in pathophysiology, diagnosis and management Am J Obstet Gynecol, 2015.PMID 25840271
17. [17]Long M, Martin J, Biggio J Atropine, Ondansetron, and Ketorolac: Supplemental Management of Amniotic Fluid Embolism Ochsner J, 2022.PMID 36189093
18. [18]Oda T, Tamura N, Kanayama N Japanese viewpoint on amniotic fluid embolism Am J Obstet Gynecol, 2017.PMID 28238668
19. [19]Jeejeebhoy FM, Zelop CM, Lipman S, et al. Cardiac Arrest in Pregnancy: A Scientific Statement From the American Heart Association Circulation, 2015.PMID 26443610