Amniotic Fluid Embolism

First Things First (assess and treat for the following)

  • Amniotic fluid embolism (AFE) occurs when there is a breach in the barrier between maternal circulation and amniotic fluid. Fetal material has been documented in the pulmonary circulation of asymptomatic women.
  • The postulated mechanisms include:
    • Obstruction of pulmonary vasculature from fetal debris
    • Inflammatory mediators leading to vasoconstriction and bronchospasm rather than mechanical factors
  • It is likely due to a combination of these factors that leads to:
    • Development of acute pulmonary hypertension and cor pulmonale
    • Sudden decrease in blood flow to the left ventricle, leading to vascular collapse
    • Ventilation/perfusion mismatches, leading to hypoxemia and its attendant complications
    • Activation of the extrinsic coagulation pathway, leading to disseminated intravascular coagulation (DIC)

History & Physical (assess for the following)

  • Signs & symptoms
    • Hypoxemia
    • Hypotension
    • Coagulopathy
    • Altered mental status
    • Seizures
    • Fetal distress
    • Fever
    • Chills
    • Headache
    • Nausea
  • The diagnosis of AFE is suspected when women present with above-mentioned signs and symptoms during:
    • Labor
    • Delivery
    • Immediate postpartum period
    • Rarely in the late postpartum period
  • AFE has also been reported following:
    • Amniocentesis
    • Therapeutic abortion
    • Abdominal trauma in pregnant individual
    • Intrapartum amnioinfusion
  • Differential diagnosis
    • Venous thromboembolism
    • Air embolism
    • Myocardial infarction
    • Septic shock
    • Preeclampsia/eclampsia
    • Postpartum hemorrhage
    • Anaphylaxis
    • Anesthetic complication
    • Transfusion reactions

Diagnostic Tests

  • The diagnosis of AFE is essentially a diagnosis of exclusion.
  • There is no laboratory or bedside investigation that can confirm the diagnosis.
  • It is suspected when a woman who is pregnant or in the immediate postpartum period acutely presents with shock along with severe respiratory distress.
  • Although most patients present in this manner, there is a subset of patients in whom the initial presentation may be severe hemorrhage secondary to DIC.
  • Occasionally the presentation may be subtle, with restlessness, altered mental status and/or hypoxemia.
  • It is important to exclude other fulminant conditions like sepsis, myocardial infarction, anaphylaxis, and transfusion reactions.
  • Labs: More than a diagnostic aid, these tests are useful in guiding resuscitation.
    • Arterial blood gas to evaluate ventilation and hypoxemia
    • DIC profile: These patients may develop DIC, as evidenced by elevated PT, PTT, low fibrinogen level and elevated fibrin split products (FSP).
    • Complete blood count: In the presence of DIC, hemoglobin and hematocrit tend to drop. Patients often develop thrombocytopenia and they usually have reactive leukocytosis.
    • Serum chemistries
  • Experimental studies have suggested that certain lab tests may be helpful:
    • Serum tryptase and histamine markers of mast cell activation (high)
    • Sialyl Tn - Fetal antigen (high)
    • Complement C3 & C4 (low)
    • Zinc coproporphyrin (high)
    • Although touted to be specific for AFE, they have no established role in confirming the diagnosis of AFE and remain experimental tools.
  • Radiographic findings are not diagnostic. Most of these patients show diffuse infiltrates suggestive of pulmonary edema.
  • An electrocardiogram should be obtained to look for signs of ischemia.
  • Echocardiogram to evaluate pulmonary artery pressure, right ventricular and left ventricular function
  • Historically, it was believed that the amniotic fluid debris found by aspirating blood from the distal port of a pulmonary artery catheter was pathognomonic of AFE; however, recent studies have shown that fetal elements can be found in some asymptomatic pregnant women.

General Management Principles

  • Given the rapidity with which AFE presents, it is essential to be vigilant and respond quickly.
  • The cornerstone of therapy is supportive care.
  • Hypoxemia
    • Supplemental oxygen while monitoring oxygen saturation
    • If hypoxemia with hemodynamic instability is present, intubation and mechanical ventilation is indicated.
    • AFE patients with ARDS should be placed on low tidal volume and high PEEP while monitoring the plateau pressure as recommended by the ARDS network.
  • Hemodynamic instability
    • These patients need to be resuscitated with fluids and vasopressors.
    • Transthoracic or transesophageal echocardiogram may be useful in guiding fluid therapy.
    • If patients are noted to have left-sided failure with pulmonary edema, therapy should include a combination of dobutamine along with either phenylephrine or norepinephrine.
    • The goal is to maintain a mean arterial pressure >65 mmHg.
  • Cardiac arrest
    • Advanced Cardiac Life Support including medications should be instituted immediately.
    • During cardiopulmonary resuscitation before delivery the uterus should be displaced to the left to avoid compression of aorta & inferior vena cava.
    • The goal is to restore maternal hemodynamics and deliver the fetus as soon as possible.
  • DIC
    • Frequent monitoring of the coagulation profile, including complete blood count and fibrinogen levels
    • Blood transfusion for hemorrhage
    • Patients need to be transfused with fresh frozen plasma & cryoprecipitate to correct coagulation abnormalities.
    • Platelet transfusions for patients with thrombocytopenia who are actively bleeding
    • Given the increased risk of bleeding with a coexisting coagulopathy, uterine atony must be treated aggressively with standard medical and surgical methods, including uterotonic medications, uterine artery embolization or ligation and hysterectomy.
  • Fetus
    • ~2/3 of patients are in labor when they are diagnosed. In these instances immediate delivery of the fetus is mandated to prevent further hypoxic damage.

Specific Management

  • N/A

Ongoing Assessment

  • AFE patients should be continuously monitored in an intensive care unit.
  • Continuous fetal monitoring until delivery is mandatory.
  • All patients need central venous IV access as well as arterial lines.


  • Maternal outcome
    • Mortality 13-86%
    • 7-85% of the survivors have neurologic deficits.
  • Fetal outcome
    • Mortality 21-22%
    • 29-50% of the survivors have neurologic deficits.


  • Jijo John, MD, and Gary T. Kinasewitz, MD

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Anesthesia Central is an all-in-one web and mobile solution for treating patients before, during, and after surgery. This collection of drugs, procedures, and test information is derived from Davis’s Drug, MGH Clinical Anesthesia Procedures, Pocket Guide to Diagnostic Tests, and PRIME Journals. .

Last updated: April 16, 2010