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Amniotic Fluid Embolism

Embolus Amniotic Fluid

Amniotic fluid embolism is a rare, but potentially fatal condition that may occur during labor or the in early postnatal period. Presumably, entrance of amniotic fluid into the maternal circulation triggers an intense inflammatory response and leads to an abrupt onset of profound hypotension, heart failure, disseminated intravascular coagulation and respiratory failure. The diagnosis is made based on clinical criteria. Ensuring hemodynamic stability and adequate oxygenation of tissues is the mainstay of therapy.


Presentation

Symptoms and signs of amniotic fluid embolism appear abruptly during labor or sometimes early postpartum period. Most common findings include sudden onset of dyspnea, acute respiratory distress, marked hypotension, hypoxia, cyanosis and coagulopathy. Severe hemorrhage and DIC are frequent manifestations, as is arrhythmia. Within minutes, cardiogenic shock develops, as a result of pulmonary hypertension and cor pulmonale, followed by pulmonary edema [5]. Convulsions, altered mental status and seizures often develop. It is important to emphasize that these symptoms appear so rapidly that cardiac arrest may occur after just several minutes, which is why attending physicians must act quickly in starting appropriate therapy.

Turkish
  • A 22-year-old Turkish woman was admitted to our antenatal clinic at 39 weeks 6 days of gestation with a complaint of decreased fetal movements for the previous 3 days.[ncbi.nlm.nih.gov]
Italian
  • The paper's authors aim to highlight the medico-legal issues, in light of several rulings from the Italian Constitutional Court as well as lower courts.[ncbi.nlm.nih.gov]
Dyspnea
  • This case report warrants that AFE should be considered when coagulopathy and dyspnea are observed during the postpartum period.[ncbi.nlm.nih.gov]
Cough
  • But after the delivery of the placenta, the patient developed an episode of coughing and dyspnea followed by unconsciousness and bradycardia. She was given adrenaline and intubated, appearing ventricular fibrillation on a EKG.[ncbi.nlm.nih.gov]
  • Those patients who do survive enter the second phase of AFE, the hemorrhagic phase, which is often accompanied by severe shortness of breath, shivering, coughing, vomiting, and excessive bleeding due to a condition called DIC (disseminated intravascular[pregnancycorner.com]
  • […] findings Acute shortness of breath, hypertension and rapid progression to cardiac arrest, leading to reduced cardiorespiratory perfusion and coma; those who survive this first phase pass to a haemorrhagic phase, which is characterised by shivering, coughing[medical-dictionary.thefreedictionary.com]
Tachypnea
  • Symptoms of pulmonary embolism include tachycardia, tachypnea, and shortness of breath, all of which are common complaints in pregnancy. Heightened awareness leads to rapid diagnosis and institution of therapy.[ncbi.nlm.nih.gov]
  • Physical exam should identify the degree of hypotension, tachycardia, tachypnea, and hypoxia. Emergent cardiopulmonary stabilization of the mother and fetus is needed and should be addressed first. C.[clinicaladvisor.com]
  • After vaginal delivery, the patient was transferred to the ICU with BP 90 60 mmHg, HR 110, and tachypnea.[scielo.br]
Orthopnea
  • An ARDS patient has clinical signs of acute hypoxemic respiratory failure: dyspnea, orthopnea, tachypnea and tachycardia ( 26). Arterial hypoxemia refractory to the oxygen supplementation is a characteristic feature of ARDS.[medichub.ro]
Hypotension
  • The diagnosis is made based on clinical criteria, the most common symptoms being abrupt development of hypotension, arrhythmia, respiratory distress, convulsions and hemorrhage.[symptoma.com]
  • The case serves to demonstrate that amniotic fluid embolism may present with symptoms and signs other than the classical pattern of dyspnoea, cyanosis and hypotension.[ncbi.nlm.nih.gov]
  • Amniotic Fluid Embolism Anaphylactoid Syndrome of Pregnancy General Considerations Rare and frequently fatal obstetrical emergency occurring in the mother most often during labor resulting in profound hypotension and dyspnea Believed to be due to amniotic[learningradiology.com]
Cyanosis
  • The case serves to demonstrate that amniotic fluid embolism may present with symptoms and signs other than the classical pattern of dyspnoea, cyanosis and hypotension.[ncbi.nlm.nih.gov]
Chest Pain
  • Patient complaints such as breathlessness, chest pain, feeling cold, distress, panic, a feeling of nausea, and vomiting should elicit close attention.[ncbi.nlm.nih.gov]
  • Amniotic fluid embolism is characterized by sudden dyspnea, chest pain, tachycardia, hypotension, and typical bluish, gray seen in patients with a pulmonary embolism. Death may occur within minutes without immediate intervention.[armymedical.tpub.com]
  • Maternal death is a frequent complication Symptoms Chest pain, dyspnea, cyanosis, tachycardia, hemorrhage, hypotension, or shock are potential symptoms. Amniotic fluid embolism is frequently fatal.[medical-dictionary.thefreedictionary.com]
  • - ‘Classic’ triad hypoxia, haemodynamic collapse, DIC APO/ALI ( 90%) Cardiac arrest ( 90%) Fetal distress (100%) SOB Bronchospasm Cough Arrhythmia Chest pain Seizure Headache Uterine atony RISK FACTORS Age 25 yrs Multiparous Obstructed labor with oxytocics[lifeinthefastlane.com]
  • Hypotension Cough Fetal distress Headache Pulmonary oedema/ARDS Chest pain Cardiopulmonary arrest Cyanosis Coagulopathy Seizures Uterine atony Bronchospasm Transient hypertension The differential diagnosis includes: obstetric causes (e.g. eclampsia,[academic.oup.com]
Tachycardia
  • Symptoms of pulmonary embolism include tachycardia, tachypnea, and shortness of breath, all of which are common complaints in pregnancy. Heightened awareness leads to rapid diagnosis and institution of therapy.[ncbi.nlm.nih.gov]
  • Amniotic fluid embolism is characterized by sudden dyspnea, chest pain, tachycardia, hypotension, and typical bluish, gray seen in patients with a pulmonary embolism. Death may occur within minutes without immediate intervention.[armymedical.tpub.com]
  • Maternal death is a frequent complication Symptoms Chest pain, dyspnea, cyanosis, tachycardia, hemorrhage, hypotension, or shock are potential symptoms. Amniotic fluid embolism is frequently fatal.[medical-dictionary.thefreedictionary.com]
  • […] sepsis Period of anxiety, change in mental status, agitation, and a sensation of “doom” may precede the event May progress rapidly to cardiac arrest, with pulseless electrical activity (PEA), asystole, ventricular fibrillation, or pulseless ventricular tachycardia[smfm.org]
Stupor
  • She was in a stupor, and her response to painful stimuli on the right side was weaker than on the left side. Acute stroke was considered as a possible cause. Additionally, an AFE was suspected due to cardiopulmonary arrest during labor.[ncbi.nlm.nih.gov]
Cesarean Section
  • We report a case of a healthy 27-yr-old gravid two, 35 wk gestation parturient with a previous Cesarean section two years previously, and presently admitted for emergent Cesarean section due to premature uterine contractions.[ncbi.nlm.nih.gov]
Vaginal Bleeding
  • Despite good uterine contractions and massive blood component therapy, vaginal bleeding continued and finally led to emergency laparotomy.[ncbi.nlm.nih.gov]
  • Continued vaginal bleeding around uterine tamponade balloon was noted by L&D nurse who remained at the bedside with the critical care team.[nursingcenter.com]
  • Delivery was uneventful, but massive vaginal bleeding without clotting and ensuing hypovolemic shock occurred 4 h later. She was transferred to the operating room for emergency laparotomy, but sustained a cardiac arrest.[jaclinicalreports.springeropen.com]
  • Following delivery, massive vaginal bleeding ensued, during which signs of disseminated intravascular coagulation were noticed by the surgical team.[degruyter.com]
Amenorrhea
  • We report the case of a patient falling victim to amniotic fluid embolism after the medical termination of her pregnancy at 24 weeks of amenorrhea following the discovery of a teratoma-carrying foetus.[ncbi.nlm.nih.gov]

Workup

The diagnosis of amniotic fluid embolism currently rests on clinical grounds. In practice, the nature of the condition mandates a rapid therapeutic approach regardless of laboratory tests. Workup comprises CBC, with emphasis on hemoglobin, hematocrit and platelet count, which are important in assessing the need for blood transfusions, as well as a full coagulation panel, including prothrombin time (PT), activated partial thromboplastin time (aPTT) and fibrinogen should be obtained, to confirm DIC. Additionally, serum electrolytes and arterial blood gas analysis should be obtained. Electrocardiography and plain chest radiography are quick and useful methods to determine the presence of arrhythmia, pulmonary edema and heart failure. At this moment, specific diagnostic markers for amniotic fluid embolism do not exist, but significant attempts toward finding tests that may aid in making the diagnosis are made [10] [11].

Hypocapnia
  • Hypocapnia caused a lower Apgar score and delayed neonatal breathing.[medichub.ro]
Decreased Platelet Count
  • However, with amniotic fluid embolism, evidence of disseminated intravascular coagulation ensues with failure of blood to clot, decreased platelet count, decreased fibrinogen and afibrinogenemia, prolonged PT and PTT, and presence of fibrin degradation[ncbi.nlm.nih.gov]
Brain Edema
  • The patient died after 5 days due to an untreatable brain edema. At autopsy, AFE with the usually associated disseminated intravascular coagulation was found in the lungs, brain, left adrenal gland, kidneys, liver and heart.[ncbi.nlm.nih.gov]

Treatment

Managing patients suffering from amniotic fluid embolism can be extremely difficult. Rapid supportive measures should be initiated as early as possible. Severe hemorrhage and anemia are often corrected with blood transfusions, sometimes including both red blood cells and plasma, to replenish coagulation factors that are depleted because of ongoing DIC. Hypotension in these patients requires administration of crystalloid solutions and vasopressor agents such as norepinephrine, dobutamine and dopamine, while correction of electrolytes is also necessary. Oxygen therapy and assisted or mechanical ventilation may be frequently required because of marked hypoxia and heart failure that is unable to compensate for generalized ischemia. Extracorporeal oxygenation, hemodialysis and plasmapheresis are techniques that have shown to life-saving in some studies [12] [13], and their use should be advocated in these patients as frequently as possible. Additionally, uterine artery embolization has shown to be a promising procedure in managing this condition [14].

Prognosis

This condition often leads to fatal outcomes and studies have indicated that death may occur only after a few hours after the onset of symptoms [9]. Mortality rates significantly reduced with advances in intensive care medicine throughout the past decades, but it is still very high, which shows the risk this condition poses to the patient. Variable mortality rates have been reported, but usually range between 20-60% [3], while mortality rates in the last decade have shown to be from 9-44% [2]. Unfortunately, women who do survive amniotic fluid embolism often have neurological sequelae.

Etiology

The exact cause and events that lead to amniotic fluid embolism are still unclear. It is established, however, that the pathogenesis almost always includes interruption of the maternal-fetal barrier and consequent introduction of amniotic fluid into the maternal circulation, which frequently occurs in conditions such as placental rupture, placenta previa, in medically induced labor and in various other conditions [5]. In addition to mechanical factors, immune-mediated reactions to fetal material that is contained in the amniotic fluid is also one of the main theories that attempt to explain the presumed etiology [5].

Epidemiology

Amniotic fluid embolism is rarely encountered in medical practice. Incidence rates have determined that this disorder develops in approximately 1 in 15,200 deliveries in North America. For unknown reasons, the incidence rate in Europe is much lower, with 1 in 59,900 deliveries developing amniotic fluid embolism [2]. After pulmonary embolism and hypertension, this condition is the most common cause of non-abortion-related maternal mortality during labor and is responsible for roughly 10% of all maternal deaths in the United States [6]. Moreover, it is the most common cause of maternal death in Australia and among the top three in the majority of developed countries [2]. Despite its ambiguous etiology, mechanical disruption of the maternal-fetal barrier is almost certain to be one of key events and various risk factors have been established in regard to this factor. Medical induction of labor, advanced maternal age, cesarean section, forceps delivery, placental rupture, placenta previa, uterine rupture, cervical lacerations and multiple-birth deliveries are shown to significantly increase the risk for amniotic fluid embolism [7].

Sex distribution
Age distribution

Pathophysiology

It is postulated that mechanical and immunological factors are the most important contributors to the development of this disorder. For amniotic fluid to reach maternal circulation, it is thought that some form for breach of the maternal-fetal barrier is necessary, leading to changes in pressure gradients that force amniotic fluid to pool into maternal vessels [2]. But invasion of amniotic fluid alone is determined to be insufficient for the pathogenesis of this disorder, which bring into question the immune-mediated mechanisms that are presumed to be involved [6]. From one hand, various contents of the amniotic fluid (meconium, particulate matter, but also various inflammatory molecules including prostaglandins and leukotrienes) are shown to be important mediators of vasoconstriction and it is assumed that some form of anaphylaxis occurs when these substances interact with the immune system of the mother; and from the other, activation of the complement system in response to these contents are shown to be of key elements in the development of severe inflammation, DIC and shock [5] [8]. Once the amniotic fluid reaches the pulmonary artery, marked vasoconstriction and pulmonary hypertension develops within a few hours, leading to cor pulmonale, right heart failure and severe hypoxia, and eventually left-heart failure and shock.

Prevention

Despite the fact that this life-threatening condition was described almost 100 years ago, the exact factors that lead to this condition remain unknown, hence prevention strategies currently do not exist.

Summary

Amniotic fluid embolism is a life-threatening obstetric complication that results in rapid patient deterioration, usually occurring either during labor or in the early postpartum period [1]. Although this medical phenomenon was initially described almost 100 years ago [2], the exact reasons for the appearance of this disorder remain unclear. It is thought that the entry of amniotic fluid into maternal circulation stems from disruption of the maternal-fetal barrier during labor and subsequent changes in pressure gradients that force amniotic fluid out of the fetal compartment. This theory is supported by the fact that a significantly increased risk for amniotic fluid embolism is established in women who present with placenta previa, polyhydramnios, abruption of the placenta and in those in whom operative deliveries were necessary [3]. This condition is seen in approximately 1 in 15,200 women in North America, while incidence in rates in Europe indicate that 1 in 59,900 deliveries are complicated by an amniotic fluid embolism [1]. The pathogenesis model, apart from amniotic fluid entry into the systemic circulation of the mother, is thought to involve a systemic inflammatory response due to the contents of the fluid. As the amniotic fluid reaches the circulation, extensive vasoconstriction occurs, especially in the pulmonary artery and results in cor pulmonale and severe right heart failure, eventually leading to severe hemodynamic instability. It is shown that amniotic fluid directly reduces coagulation time, activates the complement cascade and induces severe coagulopathy by interfering with various factors involved in this process [4]. Disseminated intravascular coagulation (DIC), initially right and followed by left heart failure, respiratory failure and shock ensue rapidly. Since this condition is known to be fatal within the first few hours in approximately 20-60% of women, early and aggressive therapy may significantly improve survival rates [3]. The diagnosis is made based on clinical criteria, the most common symptoms being abrupt development of hypotension, arrhythmia, respiratory distress, convulsions and hemorrhage. Guided by laboratory studies comprising of a complete blood count (CBC), coagulation panel, serum electrolytes and arterial blood gasses, treatment aims to stabilize blood pressure and tissue oxygenation that often calls for blood transfusions, assisted ventilation, fluid administration, use of vasopressors and various other strategies that are required to restore hemodynamic stability.

Patient Information

Amniotic fluid embolism is a rare but often life-threatening condition that develops during birth or shortly after birth. It is established to occur approximately once in every 15,000-60,000 deliveries and despite that almost a century has passed since this condition was described in literature, the exact cause remains unknown. Several conditions have shown to increase the risk for developing this condition, including rupture of the placenta, multiple-birth pregnancies, placenta previa, advanced age of the mother, but also medical induction of labor and cesarean delivery. It is hypothesized that the barrier that separates the fetus and the mother is disrupted during labor, which leads to passage of amniotic fluid into maternal blood vessels. More importantly, various components of the amniotic fluid supposedly cause a marked inflammatory reaction in the mother, leading to abrupt and profound changes in the circulatory system. Rapid development of severe symptoms such as hypotension, arrhythmia, heart failure, respiratory arrest and shock is observed. Severe bleeding and marked disturbances in blood coagulation are frequent, together with convulsions and seizures. The diagnosis is made based on clinical grounds, as the rapid onset and profound deterioration of the condition of the patient during labor are hallmarks of amniotic fluid embolism. Treatment aims to restore blood pressure and establish adequate oxygenation of tissues through administering both blood and plasma transfusions and intravenous fluids together with drugs that increase tension of blood vessels. Because cessation of breathing may occur within minutes after onset, oxygen therapy and either assisted or mechanical ventilation are indicated to prevent lung failure. Recently, various techniques that can more efficiently reach adequate blood pressure control have been recommended in these patients, such as hemodialyis and extracorporeal oxygenation, which includes the use of machines for inserting oxygen into the circulation. Amniotic fluid embolism is often a fatal condition, with maternal mortality rates reaching up to 60%, which is why early and aggressive treatment within the first few minutes after the onset of symptoms can save the patient. Unfortunately, prevention strategies of this condition remain to be created ad women who survive this condition often have long-term neurological sequelae, which illustrates the danger this condition poses.

References

Article

  1. Conde-Agudelo A, Romero R. Amniotic fluid embolism: An evidence-based review. Am J Obstet Gynecol. 2009;201(5):445.e1-445.13.
  2. Meyer JR. Embolis pulmonary caseosa. Braz J Med Biol Res 1926;1:301-303.
  3. Clark SL. Amniotic fluid embolism. Obstet Gynecol. 2014;123(2 pt 1):337-348.
  4. Courtney LD, Allington M. Effect of amniotic fluid on blood coagulation. Br J Haematol. 1972;22:353–355.
  5. Rossi SE, Goodman PC, Franquet T. Nonthrombotic pulmonary emboli. AJR Am J Roentgenol. 2000;174(6):1499-508.
  6. Benson MD. Current concepts of immunology and diagnosis in amniotic fluid embolism. Clin Dev Immunol. 2012;946576.
  7. Kramer MS, Rouleau J, Baskett TF, Joseph KS,. Amniotic-fluid embolism and medical induction of labour: a retrospective, population-based cohort study. Lancet. 2006;368(9545):1444-1448.
  8. Clark SL. New concepts of amniotic fluid embolism: a review. Obstet Gynecol Surv 1990;45:360-368.
  9. Clark SL, Hankins GDV, Duddley D, Didly G, Porter T. Amniotic fluid embolism: analysis of the national registry. Am J Obstet Gynecol 1995;172:1158-1169.
  10. Farrar SC, Gherman RB. Serum tryptase analysis in a woman with amniotic fluid embolism. A case report. J Reprod Med. 2001;46(10):926-928.
  11. Kobayashi H, Ohi H, Terao T. A simple, noninvasive, sensitive method for diagnosis of amniotic fluid embolism by monoclonal antibody TKH-2 that recognizes NeuAc alpha 2-6GalNAc. Am J Obstet Gynecol. 1993;168(3 Pt 1):848-853.
  12. Kaneko Y, Ogihara T, Tajima H, Mochimaru F. Continuous hemodiafiltration for disseminated intravascular coagulation and shock due to amniotic fluid embolism: report of a dramatic response. Intern Med. 2001;40(9):945-947.
  13. Hsieh YY, Chang CC, Li PC, Tsai HD, Tsai CH. Successful application of extracorporeal membrane oxygenation and intra-aortic balloon counterpulsation as lifesaving therapy for a patient with amniotic fluid embolism. Am J Obstet Gynecol. 2000;183(2):496-497.
  14. Goldszmidt E, Davies S. Two cases of hemorrhage secondary to amniotic fluid embolus managed with uterine artery embolization. Can J Anaesth. 2003;50(9):917-921.

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Last updated: 2019-07-11 20:45