Immune storm and coagulation storm in the pathogenesis of amniotic fluid embolism.

Amniotic fluid embolism (AFE) is a rare but severe obstetric complication with high mortality. To date, the pathogenesis of AFE has evolved from a simple theory of mechanical obstruction to an immunological theory. However, it is not yet fully understood. Here we elaborate on the immune storm and coagulation storm induced by the amniotic fluid entering the maternal circulation. These two storms contribute to a better understanding of the pathogenesis of typical and atypical AFE. Our theory needs to be confirmed by further clinical studies and basic research.

Amniotic fluid embolism: lessons for rapid recognition and intervention

Amniotic fluid embolism is a rare, often fatal complication of labor and delivery. The classic presentation is the sudden onset of a triad of clinical manifestations: hypoxia, hypotension and coagulopathy. Understanding of the syndrome as an immunologically mediated, complicated and often catastrophic maternal response to fetal or placental antigens is coming into focus. New treatments such as extracorporeal membrane oxygenation (ECMO) and better use of old treatments such as transfusion offer hope, but the condition is often rapidly fatal, so saving the maternal and fetal lives depends on rapid recognition of the syndrome. This series of three cases illustrates the clinical features enabling the rapid recognition needed for successful treatment of amniotic fluid embolism syndrome.

Consumptive Coagulopathy Involving Amniotic Fluid Embolism: The Importance of Earlier Assessments for Interventions in Critical Care.

OBJECTIVES: Amniotic fluid embolism is a rare disease that induces fatal coagulopathy; however, due to its rarity, it has not yet been examined in detail. The strict diagnostic criteria by Clark for amniotic fluid embolism include severe coagulopathy complicated by cardiopulmonary insufficiency, whereas the Japanese criteria also include postpartum hemorrhage or Disseminated Intravascular Coagulation in clinical practice. Amniotic fluid embolism cases with preceding consumptive coagulopathy may exist and are potential clinical targets for earlier assessments and interventions among amniotic fluid embolism cases fulfilling the Japanese, but not Clark criteria. The present study was performed to compare coagulopathy in the earlier stage between the amniotic fluid embolism patients diagnosed by Clark criteria (Clark group, n = 6), those by the Japanese criteria (Non-Clark group, n = 10), and peripartum controls and identify optimal clinical markers for earlier assessments of amniotic fluid embolism-related consumptive coagulopathy. DESIGN: Retrospective case-control study. SETTING: A single university-based center. Our amniotic fluid embolism registry program has accumulated clinical information and blood samples since 2003. PATIENTS: Amniotic fluid embolism patients in the Clark and Non-Clark groups between 2009 and 2017 and peripartum controls. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Clinical information was collected on hemoglobin levels, platelet counts, and coagulation- and fibrinolysis-related variables. Fibrinolytic parameters were also measured and compared among the three groups before blood transfusion. Fibrinogen levels in all patients in the Clark group and most in the Non-Clark group decreased earlier than hemoglobin levels, which was consistent with the high hemoglobin/fibrinogen ratio and, thus, is a promising clinical marker for the earlier assessment of amniotic fluid embolism-related consumptive coagulopathy. CONCLUSIONS: Earlier evaluations of consumptive coagulopathy and hyperfibrinolysis using the hemoglobin/fibrinogen ratio following preemptive treatment may reduce the occurrence or prevent the aggravation of severe coagulopathy in amniotic fluid embolism patients.

Pulmonary amniotic fluid embolism in a rhesus macaque (Macaca mulatta).

A pregnant female rhesus macaque died spontaneously during stage two labor. Gross and histopathologic findings included severe pulmonary edema, with low numbers of blood vessels containing pale basophilic mucinous material (Alcian Blue positive and PTAH negative), consistent with intravascular amniotic fluid-derived mucin resulting in pulmonary amniotic fluid embolism.

Perinatal Maternal Mortality in Sickle Cell Anemia: Two Case Reports and Review of the Literature.

As outcomes of patients with sickle cell anemia improve and survival into adulthood with good quality of life and expectation of long-term survival becomes more common, challenges have developed, including issues related to reproduction. Pregnancy is frequently complicated in patients with sickle cell anemia with mortality up to 4.0%. Here we report maternal perinatal mortality in two women with sickle cell anemia who died post-partum due to acute chest syndrome (ACS), caused by bone marrow fat embolism and review the literature pertinent to this subject. Patient A was a 28-year-old woman with sickle cell anemia with multiple complications. At 30 weeks' gestation she developed hemolysis associated with poor placental function necessitating delivery by C-section. The fetus was delivered successfully but she died due to multi organ failure after delivery. Autopsy showed pulmonary and amniotic fluid embolization. Patient B was a 37-year-old woman with uncomplicated sickle cell anemia who presented with pre term labor and crisis, then ACS and fetal distress. The infant was delivered successfully but the patient died after cardiovascular collapse. Autopsy results showed fat and bone marrow embolization as the cause of death. Pregnancy continues to be high risk for patients with sickle cell anemia including those with mild disease. Maternal perinatal mortality could be unpredictable due to serious complications of sickle cell disease. More studies to assess maternal perinatal mortality are needed.

Amniotic fluid embolism: Pathophysiology from the perspective of pathology.

Amniotic fluid embolism (AFE) is recognized as a type of syndrome characterized by the abrupt onset of hypoxia, hypotension, seizures, or disseminated intravascular coagulopathy (DIC), occurring during labor, delivery, or immediately postpartum, caused by the inflow of amniotic components into the maternal circulation. AFE is a rare condition but one of the most serious obstetrical complications, resulting in a high mortality rate among pregnant women. Despite earlier recognition and intensive critical management, we often encounter patients who unfortunately do not recover from the exacerbation of AFE-related conditions. A major concern is that there are no effective evidence-based therapies for AFE, because its pathophysiology is still not well understood. This article reviewed AFE, focusing on the pathology and currently proposed pathophysiology.

Procoagulant extracellular vesicles in amniotic fluid.

Embolization of amniotic fluid (AF) into the blood circulation leads to disseminated intravascular coagulation (DIC). Procoagulant phosphatidylserine (PS)- and tissue factor (TF)-exposing extracellular vesicles (EVs) might play an important role in AF embolism-induced DIC. It was the aim of the present study to perform analyses of the procoagulant properties of AF with a panel of functional coagulation assays and flow cytometry. We applied a prothrombinase assay (that quantifies PS exposure on EVs), an EV-associated TF activity assay, a fibrin generation assay, a thrombin generation assay, a whole blood clotting model, and flow cytometry in AF and control plasma. We found that PS exposure on EVs was 21-fold increased in AF compared with plasma. Also, EV-associated TF activity was highly increased in AF compared with plasma. AF-derived EVs activated the blood coagulation cascade via PS and TF in the fibrin and thrombin generation assays. In a whole blood clotting model, AF-derived EVs significantly shortened the clotting time from 734 ± 139 seconds in the presence to 232 ± 139 seconds in the absence of an anti-TF antibody. The contact activation pathway via factor XII (FXII) was not affected. Applying flow cytometry, a subpopulation of PS+ and TF+ EVs was identified in AF but not in control plasma. In conclusion, we investigated the effect of AF on blood coagulation and found that PS+ and TF+ EVs determine their procoagulant potential. Taken together, our data further delineate the pathomechanisms underlying AF-induced coagulopathy.

Clinical course of disseminated intravascular coagulopathy-type amniotic fluid embolism: A report of three cases.

Amniotic fluid embolism (AFE) is a rare complication of pregnancy and its mortality rate is high. There have been few reports of AFE with presence of severe coagulopathy and incoagulable bleeding, and absence of cardiopulmonary symptoms or limited cardiopulmonary symptoms, followed by massive blood loss during delivery. Such cases have been referred to as disseminated intravascular coagulopathy-type AFE, and the characteristics of this condition have been presented previously. Here we report three cases that fulfilled the diagnostic characteristics of disseminated intravascular coagulopathy-type AFE.

Embolismo de líquido amniótico: mitos y realidades etiopatogénicas de un síndrome potencialmente fatal / Amniotic fluid embolism: etiopathogenic realities and myths of a potentially fatal syndrome

Fundamento: el embolismo de líquido amniótico es un síndrome catastrófico que ocurre durante el trabajo de parto, el parto o inmediatamente. De incidencia variable, es la segunda causa de muerte materna en muchas partes del mundo y que reporta tasas de hasta un 60 por ciento en países desarrollados. En las últimas dos décadas un trabajo de investigación más riguroso ha mejorado enormemente la comprensión de esta condición.Objetivo: exponer los elementos más recientes que intentan explicar la etiología y la fisiopatología del embolismo de líquido amniótico.Método: se realizó una revisión en 32 bibliografías entre revistas y textos clásicos, a través de la biblioteca virtual cubana, Lilacs, PubMed y Medline.Desarrollo: la embolia de líquido amniótico es, desde un punto de vista fisiopatológico, parecida al síndrome de respuesta inflamatoria sistémica, común en condiciones tales como choque séptico, en el que una respuesta anormal del huésped es la principal responsable de las manifestaciones clínicas. La teoría bimodal es la regla: una fase temprana caracterizada por vasoespasmo e hipertensión pulmonar y fallo ventricular derecho; otra tardía donde prima el fallo ventricular izquierdo, el edema pulmonar, el shock y los trastornos de la coagulación.Conclusiones: la base fisiopatológica de toda esta secuencia de alteraciones hemodinámicas parece implicar una secuencia compleja de reacciones resultantes de la activación anormal de sistemas mediadores pro inflamatorios similares a los presentes en el síndrome de respuesta inflamatoria sistémica, que sigue al casi universal paso de antígenos fetales a la circulación materna durante el proceso de parto(AU)

Background: amniotic fluid embolism is a catastrophic syndrome that takes place during the onset of labor or during the labor. This syndrome of variable incidence is the second cause of maternal death in many regions of the world. Rates up to 60 percent are reported in developed countries. A more rigid investigation has greatly increased the comprehension of this condition in the last two decades.Objective: to set out the most recent elements that try to explain the etiology and physiopathology of amniotic fluid embolism.Method: a review of 32 bibliographies, including journals and classic texts, was made through the Cuban virtual library, Lilacs, PubMed and Medline.Development: amniotic fluid embolism is, from the physiopathological point of view, similar to the systemic inflammatory response syndrome, and it is common in conditions like septic shock, in which the abnormal response of the host is the main responsible for the clinical manifestations. Bimodal theory is the rule: an early stage characterized by vasospasm and pulmonary hypertension and heart failure; and a late stage where left heart failure, pulmonary edema, shock and coagulation disorders predominate.Conclusions: the physiopathological basis of this sequence of hemodynamic changes seems to entail a complex sequence of reactions that result from the abnormal activation of proinflammatory mediator systems, similar to those present in the systemic inflammatory response syndrome that follows the almost universal flow of fetal antigens to the maternal circulation during labor(AU)

Amniotic fluid embolism: pathophysiology and new strategies for management.

The registry program of amniotic fluid embolism (AFE) in Japan started in 2003. More than 400 hundred clinical diagnosed amniotic fluid embolism has been accumulated. Those data showed that there were two etiologies of AFE: the fetal materials create physical obstructions in the maternal microvessels in various organs, such as the lung; and (ii) the liquids cause an anaphylactoid reaction that leads to pulmonary vasospasm and activation of platelets, white blood cells and/or complements. The clinical findings showed that AFE was characterized mainly by cardiopulmonary collapse, the other involves the presence of disseminated intravascular coagulation (DIC) and atonic bleeding. Zinc coproporphyrin-1, sialyl Tn antigen (STN), complement C3, C4 and interleukin-8 have been used as serum markers of AFE. The levels of zinc coproporphyrin-1 and STN were increased in cardiopulmonary collapse type AFE, and a marked reduction of C3 and C4 was observed in DIC type AFE. At the primary medical institution, initial treatments for shock airway management, vascular management, fluid replacement, administration of anti-DIC therapy such as antithrombin, and administration of fresh frozen plasma should be provided. C1 esterase inhibitor activity in AFE cases was significantly lower than those of normal pregnant women. C1 esterase inhibitor may be a promising candidate of treatment of AFE.

Amniotic fluid embolism induces uterine anaphylaxis and atony following cervical laceration.

Amniotic fluid embolism (AFE) is a rare, high-risk obstetric complication primarily found in the lungs and potentially related to anaphylaxis. Tryptase release from the mast cell reflects anaphylaxis. Case report and findings: A female, aged over 40 years, presented with uterine atony and lethal hemorrhage after induced vaginal labor. Cervical laceration was accompanied by severe hemorrhage. Stromal edema and myometrial swelling were consistent with uterine atony. Alcian blue staining and zinc coproporphyrin immunostaining disclosed AFE, which was more prominent in the uterus than in the lungs. Tryptase immunostaining was diffuse and prominent around the activated mast cells (halos) in the uterus, including the cervix. Similar distribution of findings on the AFE markers, tryptase halos, complement receptor C5aR, and atony in the uterus suggested the causality of AFE to anaphylaxis, complement activation and atony. It is probable that disseminated intravascular coagulation (DIC), induced by AFE, uterine atony and cervical laceration, caused the lethal hemorrhage. It is likely that AFE, in association with cervical laceration, induces uterine anaphylaxis, complement activation, atony, DIC and lethal hemorrhage.

Cardiac magnetic resonance imaging in a patient with amniotic fluid embolism associated with severe cardiopulmonary complications.

Amniotic fluid embolism (AFE) is a rare but devastating complication of pregnancy. Acute circulatory failure and obstetric disseminated intravascular coagulopathy are often associated with AFE and lead to poor prognosis of this syndrome. Although many reports of AFE and its cardiopulmonary complications exist, their etiology remains unknown. Classically, it was believed that the fatal cardiopulmonary complication in AFE is due to acute and severe pulmonary hypertension caused by critical obstruction of the pulmonary vessels by embolized amniotic fluid. However, recent hypotheses are suggesting that anaphylactic reaction or a cytokine effect induced by amniotic fluid is the main pathophysiological mechanism. We report a case in which cardiac magnetic resonance imaging was performed at the chronic stage of AFE. Late gadolinium enhancement (LGE) was detected at the mid-wall of the left ventricle with no evidence of pulmonary hypertension. This finding suggests that the pathophysiological mechanism of severe cardiac complications in AFE may include direct left ventricular myocardial injury through an immune reaction or cytokine release, rather than pulmonary embolism.

Embolismo de líquido amniótico. Presentación de un caso / Amniotic fluid embolism. A case report

El embolismo de líquido amniótico (ELA) es un síndrome obstétrico que suele presentarse de manera abrupta en el parto o en el posparto inmediato, con un comienzo agudo de disnea o colapso cardiovascular. El ELA es difícil de diagnosticar en vida, ya que no existen pruebas analíticas específicas para la enfermedad. Presentamos un caso de ELA en una mujer de 37 años de edad que desarrolló un cuadro súbito de disnea y shock cardiovascular en el trabajo de parto. Se estableció la sospecha clínica de ELA y se procedió a una cesárea urgente. La paciente falleció, pero el feto sobrevivió. En la autopsia se demostró la presencia de componentes del líquido amniótico en los vasos del endocérvix uterino y los espacios alveolares pulmonares, confirmando la sospecha clínica(AU)

Amniotic fluid embolism (AFE) is a rare obstetric syndrome occurring abruptly during delivery or the postpartum characterized by acute onset of dyspnea or haemodynamic collapse. Clinical diagnosis is often difficult due to the lack of specific tests. We present a case of AFE in a 37-year-old woman who developed abrupt dyspnea and cardiogenic shock during labour. An emergency caesarian section was performed due to the suspicion of AFE. The patient died but the foetus survived. The autopsy revealed amniotic components within the endocervix vessels and lung alveolar spaces, thus confirming the clinical diagnosis(AU)

[Amniotic fluid embolism: an update]. / L'embolie amniotique : mise au point.

Amniotic fluid embolism (AFE) results from the passage of fœtal and amniotic fragments into the maternal circulation, occurring mostly within minutes before or after delivery. Although maternal and fœtal mortality of AFE remains high (about 40%), AFE should no longer be considered as having an ineluctable fatal course. Diagnosis is often made upon clinical presentation but histological confirmation is difficult owing favorable outcome and because an autopsy has not been performed. Identification of squamous cells in the maternal circulation could not confirm the diagnosis because of their possible maternal origin. High plasma level of insulin-like growth factor-binding protein-1 (IGFBP-1) has recently been identified as a biomarker of amniotic fluid passage into the maternal circulation and might therefore be used to confirm the diagnosis when lung tissue histology is not available. Treatment of AFE remains supportive with a special focus on correction of the coagulopathy and search for acute core pulmonale. In this later case, physicians should consider initiating an extracorporeal life support when facing a patient with refractory shock. Finally, caution is needed with the use of recombinant factor VIIa in this context.