United Kingdom Amniotic Fluid Embolism Register

Anesthetic Considerations and Outcomes in Amniotic Fluid Embolism: A Retrospective Study over a 15-Year Period

(1) Background: A rare and unexpected consequence of childbirth, labor, or the immediate postpartum period is amniotic fluid embolism (AFE). This study aims to identify AFE cases during or immediately after birth from anesthetic management perspectives. Secondary goals include assessing patient clinical features, obstetric care techniques, birth outcomes, and case survival. (2) Methods: A retrospective observational study assessed AFE patients hospitalized in three Romanian clinical institutions from October 2007 to April 2023. Based on the Society of Maternal-Fetal Medicine (SMFM) criteria, we diagnosed 11 AFE patients. (3) Results: AFE occurred in eight cases (73%) during peripartum, two (18%) within 30 min after placental delivery, and 1 (9%) during a scheduled cesarean surgery. Only one of six cardiorespiratory arrest patients responded to external cardiac massage, while the other five (83%) needed defibrillation. The patients received, on average, five units of red blood cells, six of fresh frozen plasma, and two of activated platelets. Six patients (55%) received factor VIIa infusions. Maternal mortality was 36.3%. Six neonates (75%) needed neonatal resuscitation, and two (25%) died on the second and third days. (4) Conclusions: AFE management necessitates a multidisciplinary approach and the incorporation of advanced life support techniques to optimize outcomes for both the mother and newborn.

Amniotic fluid embolism: A case report of good outcome with timely intensive multidisciplinary team involvement

OBJECTIVE

Amniotic fluid embolism is one of the most serious pregnancy complications. It can cause sudden maternal collapse with high mortality and morbidity. We present a case report regarding the important of prompt decision making and multidisciplinary team work for management of amniotic fluid embolism to yield favorable maternal and neonatal outcome.

CASE REPORT

This is a 35-year-old, gravida 2, para 1, woman underwent labor induction at gestational age of 37 + 6 weeks due to elective induction. She had sudden facial cyanosis and shortness of breath right after artificial rupture of membrane. Prompt decision of urgent cesarean section, aggressive and timely massive blood transfusion and multidisciplinary team work had spared patient from extracorporeal membrane oxygenation placement and prolonged hospitalization. A male infant was born with Apgar score 3' -> 5' with estimate body weight of 2958 gm; he was hospitalized for 10 days and no other complications was found at follow up pediatric outpatient clinic.

CONCLUSION

One of the most dreadful, but rare pregnancy complications is amniotic fluid embolism (AFE). It can cause serious maternal and neonatal morbidity and mortality. Rapid recognition and multidisciplinary team management are essential to maternal and neonatal prognosis.

Acute respiratory distress and amniotic fluid embolism in pregnancy

Respiratory failure in pregnant and postpartum women is uncommon, but it is one of the leading causes of maternal admission into the intensive care unit and is associated with high mortality. The underlying causes include sequelae of underlying medical conditions, such as congenital heart diseases, but it is more often related to acute respiratory distress syndrome from obstetric complications like pre-eclampsia, effect of treatment like tocolysis, coincidental to pregnancy like transfusion-related acute lung injury, and accidental like amniotic fluid embolism. The pathophysiological mechanisms involved in many of these conditions remain to be clearly established, but maternal inflammatory response and activation of the immune and complement systems appear to play leading roles. Prompt recognition of maternal respiratory distress and related manifestations and aggressive and adequate supportive treatment, especially cardiopulmonary resuscitation, ventilation, maintenance of circulation, and timely termination of the pregnancy, play key roles in achieving survival of both mother and foetus.

Amniotic fluid embolism - implementation of international diagnosis criteria and subsequent pregnancy recurrence risk

OBJECTIVES

An international diagnostic criterion for amniotic fluid embolism (AFE) diagnosis has recently been published. Data regarding subsequent pregnancies is scarce. We sought to implement recent diagnostic criteria and detail subsequent pregnancies in survivors.

METHODS

A case series of all suspected AFE cases at a tertiary medical center between 2003 and 2018 is presented. Cases meeting the diagnostic criteria for AFE were included. Clinical presentation, treatment, and outcomes described. Pregnancy outcomes in subsequent pregnancies in AFE survivors detailed.

RESULTS

Between 2003 and 2018 14 women were clinically suspected with AFE and 12 of them (85.71%) met the diagnostic criteria for AFE. Three cases occurred during midtrimester dilation and evacuation procedures, and the remaining occurred in the antepartum period. Of the antepartum cases, mode of delivery was cesarean delivery or vacuum extraction for expedited delivery due to presentation of AFE in 8/9 cases (88.88%). Clinical presentation included cardiovascular collapse, respiratory distress and disseminated intravascular coagulopathy (DIC). Heart failure of varying severity was diagnosed in 75% (9/12) cases. Composite maternal morbidity was 5/12 (41.66%), without cases of maternal mortality. 11 subsequent pregnancies occurred in four AFE survivors. Pregnant women were followed by a high-risk pregnancy specialist and multidisciplinary team if pregnancy continued beyond the early second trimester. Six pregnancies resulted in a term delivery. No recurrences of AFE were documented.

CONCLUSIONS

Use of a diagnostic criterion for diagnosis of AFE results in a more precise diagnosis of AFE. Nevertheless, the accuracy of clinical diagnosis is still high. Subsequent pregnancies were not associated with AFE recurrence.

Fibrinogen may aid in the early differentiation between amniotic fluid embolism and postpartum haemorrhage: a retrospective chart review

This study aimed to determine whether blood loss and fibrinogen can differentiate amniotic fluid embolism (AFE) from postpartum haemorrhage (PPH). This retrospective case–control study included nine patients with clinical AFE (“AFE group”) and 78 patients with PPH managed at our tertiary care perinatal centre between January 2014 and March 2016. Patients meeting the Japanese diagnostic criteria for AFE were stratified into cardiopulmonary collapse-type AFE and disseminated intravascular coagulation (DIC)-type AFE groups. The relationship between blood loss and fibrinogen at onset was examined to compare DIC severity. Vital signs at onset were not significantly different. The AFE group had significantly less blood loss at onset (1506 mL vs 1843 mL, P = 0.0163), significantly more blood loss 2 h post-onset (3304 mL vs 1996 mL, P < 0.0001) and more severe coagulopathy and fibrinolysis. The blood loss/fibrinogen (B/F) ratio at onset was significantly higher in the DIC-type AFE group (23.15 ± 8.07 vs 6.28 ± 3.35 mL dL/mg, P < 0.0001). AFE was complicated by catastrophic DIC irrespective of blood loss at onset. Fibrinogen exhibited the strongest correlation among test findings at onset. The B/F ratio may help differentiate PPH from DIC-type AFE and diagnose clinical AFE, facilitating optimal replacement of coagulation factors during the early stages.

Reference range for C1-esterase inhibitor (C1 INH) in the third trimester of pregnancy

OBJECTIVES

The objectives of this study were to (i) establish the reference range and mean value for normal levels of C1-esterase inhibitor (C1 INH) during pregnancy, and (ii) investigate the association between C1 INH and uterine atony, as measured by blood loss at delivery.

METHODS

We prospectively studied 200 healthy pregnant women who were registered. We studied C1 INH levels in 188 women at 34 and 35 gestational weeks of pregnancy. The reference range for C1 INH during the third trimester of pregnancy was calculated using the value of C1 INH that was determined at registration.

RESULTS

The mean value of C1 INH was determined to be 70.3% (95% confidence interval, 68.7-71.9). While the C1 INH levels in four women were determined to be 40% lower than the calculated mean value, amniotic fluid embolism (AFE) did not occur in any of the women studied.

CONCLUSIONS

This study successfully demonstrated that a reference value for C1 INH activity can be established using the methods described herein. Further research is needed to determine whether C1 INH is involved in obstetric coagulopathy syndrome such as amniotic fluid embolism.

Amniotic fluid embolism syndrome: analysis of the Unites States International Registry

BACKGROUND

Incidence, risk factors, and perinatal morbidity and mortality rates related to amniotic fluid embolism remain a challenge to evaluate, given the presence of differing international diagnostic criteria, the lack of a gold standard diagnostic test, and a significant overlap with other causes of obstetric morbidity and mortality.

OBJECTIVE

The aims of this study were (1) to analyze the clinical features and outcomes of women using the largest United States-based contemporary international amniotic fluid embolism registry, and (2) to investigate differences in demographic and obstetric variables, clinical presentation, and outcomes between women with typical versus atypical amniotic fluid embolism, using previously published and validated criteria for the research reporting of amniotic fluid embolism.

MATERIALS AND METHODS

The AFE Registry is an international database established at Baylor College of Medicine (Houston, TX) in partnership with the Amniotic Fluid Embolism Foundation (Vista, CA) and the Perinatology Research Branch of the Division of Intramural Research of the NICHD/NIH/DHHS (Detroit, MI). Charts submitted to the registry between August 2013 and September 2017 were reviewed, and cases were categorized into typical, atypical, non-amniotic fluid embolism, and indeterminate, using the previously published and validated criteria for the research reporting of AFE. Demographic and clinical variables, as well as outcomes for patients with typical and atypical AFE, were recorded and compared. Student t tests, χ2 tests, and analysis of variance tables were used to compare the groups, as appropriate, using SAS/STAT software, version 9.4.

RESULTS

A total of 129 charts were available for review. Of these, 46% (59/129) represented typical amniotic fluid embolism and 12% (15/129) atypical amniotic fluid embolism, 21% (27/129) were non-amniotic fluid embolism cases with a clear alternative diagnosis, and 22% (28/129) had an uncertain diagnosis. Of the 27 women misclassified as an amniotic fluid embolism with an alternative diagnosis, the most common actual diagnosis was hypovolemic shock secondary to postpartum hemorrhage. Ten percent (6/59) of the women with typical amniotic fluid embolism had a pregnancy complicated by placenta previa, and 8% (5/61) had undergone in vitro fertilization to achieve pregnancy. In all, 66% (49/74) of the women with amniotic fluid embolism reported a history of atopy or latex, medication, or food allergy, compared to 34% of the obstetric population delivered at our hospital over the study period (P < .05).

CONCLUSION

Our data represent a series of women with amniotic fluid embolism whose diagnosis has been validated by detailed chart review, using recently published and validated criteria for research reporting of amniotic fluid embolism. Although no definitive risk factors were identified, a high rate of placenta previa, reported allergy, and conceptions achieved through in vitro fertilization was observed.

Extracorporeal Therapies for Amniotic Fluid Embolism

BACKGROUND

Amniotic fluid embolism (AFE) is a catastrophic disease with significant mortality. Because the cardiopulmonary dysfunction associated with AFE is self-limited, the disease could be well suited to the use of extracorporeal therapies.

CASE

A woman progressed into cardiac arrest immediately after an elective cesarean delivery. Owing to severe hypoxemia and hypotension, AFE was suspected and peripheral venoarterial extracorporeal membrane oxygenation was quickly initiated. Subsequent evolution was complicated by intrabdominal bleeding, which required massive transfusion and multiple surgeries. The patient recovered well, with a healthy newborn. We have identified 19 similar cases in the literature and present their outcomes as a series.

CONCLUSION

Extracorporeal therapies can support severely ill women affected by AFE and could be considered even in the presence of disseminated intravascular coagulation and bleeding.

Restrictive versus Liberal Fluid Therapy for Post-Cesarean Acute Kidney Injury in Severe Preeclampsia: a Pilot Randomized Clinical Trial

OBJECTIVES

The aim of this study was to determine whether a restrictive compared to a liberal fluid therapy will increase postoperative acute kidney injury (AKI) in patients with severe preeclampsia.

METHODS

A total of 46 patients (mean age, 32 years; standard deviation, 6.8 years) with severe preeclampsia were randomized to liberal (1500 ml of lactated Ringer's, n=23) or restrictive (250 ml of lactated Ringer's, n=23) intravenous fluid regimen during cesarean section. The primary outcome was the development of a postoperative renal dysfunction defined by AKI Network stage ≥1. Serum cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) were evaluated at postoperative days 1 and 2. ClinicalTrials.gov: NCT02214186.

RESULTS

The rate of postoperative AKI was 43.5% in the liberal fluid group and 43.5% in the restrictive fluid group (p=1.0). Intraoperative urine output was higher in the liberal (116 ml/h, IQR 69-191) than in the restrictive fluid group (80 ml/h, IQR 37-110, p<0.05). In both groups, serum cystatin C did not change from postoperative day 1 compared to the preoperative period and significantly decreased on postoperative day 2 compared to postoperative day 1 (p<0.05). In the restrictive fluid group, NGAL levels increased on postoperative day 1 compared to the preoperative period (p<0.05) and decreased on postoperative day 2 compared to postoperative day 1 (p<0.05).

CONCLUSION

Among patients with severe preeclampsia, a restrictive fluid regimen during cesarean section was not associated with increased postoperative AKI.

Amniotic fluid embolism mortality rate

AIM

The objective of this study was to determine the mortality rate of amniotic fluid embolism (AFE) using population-based studies and case series.

METHODS

A literature search was conducted using the two key words: 'amniotic fluid embolism (AFE)' AND 'mortality rate'. Thirteen population-based studies were evaluated, as well as 36 case series including at least two patients.

RESULTS

The mortality rate from population-based studies varied from 11% to 44%. When nine population-based studies with over 17 000 000 live births were aggregated, the maternal mortality rate was 20.4%. In contrast, the mortality rate of AFE in case series varies from 0% to 100% with numerous rates in between.

CONCLUSION

The AFE mortality rate in population-based studies varied from 11% to 44% with the best available evidence supporting an overall mortality rate of 20.4%. Data from case series should no longer be used as a basis for describing the lethality of AFE.

Amniotic Fluid Embolism. Is a New Pregnancy Possible? Case Report

Amniotic fluid embolism (AFE) is a rare but potentially catastrophic clinical condition, characterized by a combination of signs and symptoms that reflect respiratory distress, cardiovascular collapse and disseminated intravascular coagulation (DIC). Its pathogenesis is still unclear. More recently, the traditional view of obstruction of pulmonary capillary vessels by amniotic fluid emboli as the main explanation for the etiology has been ruled out, and immunologic factors and the activation of the inflammatory cascade took on an important role. Amniotic fluid embolism has an unpredictable character, its diagnosis is exclusively clinical, and the treatment consists mainly of cardiovascular support and administration of blood products to correct the DIC. No diagnostic test is recommended until now, though multiple blood markers are currently being studied. The authors present a case report of a woman who had survived AFE in her previous pregnancy and had a subsequent pregnancy without recurrence, providing one more clinical testimony of the low risks for the pregnancy after AFE.

Proposed diagnostic criteria for the case definition of amniotic fluid embolism in research studies

Amniotic fluid embolism is a leading cause of maternal mortality in developed countries. Our understanding of risk factors, diagnosis, treatment, and prognosis is hampered by a lack of uniform clinical case definition; neither histologic nor laboratory findings have been identified unique to this condition. Amniotic fluid embolism is often overdiagnosed in critically ill peripartum women, particularly when an element of coagulopathy is involved. Previously proposed case definitions for amniotic fluid embolism are nonspecific, and when viewed through the eyes of individuals with experience in critical care obstetrics, would include women with a number of medical conditions much more common than amniotic fluid embolism. We convened a working group under the auspices of a committee of the Society for Maternal-Fetal Medicine and the Amniotic Fluid Embolism Foundation whose task was to develop uniform diagnostic criteria for the research reporting of amniotic fluid embolism. These criteria rely on the presence of the classic triad of hemodynamic and respiratory compromise accompanied by strictly defined disseminated intravascular coagulopathy. It is anticipated that limiting research reports involving amniotic fluid embolism to women who meet these criteria will enhance the validity of published data and assist in the identification of risk factors, effective treatments, and possibly useful biomarkers for this condition. A registry has been established in conjunction with the Perinatal Research Branch of the Eunice Kennedy Shriver National Institute of Child Health and Human Development to collect both clinical information and laboratory specimens of women with suspected amniotic fluid embolism in the hopes of identifying unique biomarkers of this condition.

Amniotic fluid embolism

Amniotic fluid embolism (AFE) is one of the catastrophic complications of pregnancy in which amniotic fluid, fetal cells, hair, or other debris enters into the maternal pulmonary circulation, causing cardiovascular collapse. Etiology largely remains unknown, but may occur in healthy women during labour, during cesarean section, after abnormal vaginal delivery, or during the second trimester of pregnancy. It may also occur up to 48 hours post-delivery. It can also occur during abortion, after abdominal trauma, and during amnio-infusion. The pathophysiology of AFE is not completely understood. Possible historical cause is that any breach of the barrier between maternal blood and amniotic fluid forces the entry of amniotic fluid into the systemic circulation and results in a physical obstruction of the pulmonary circulation. The presenting signs and symptoms of AFE involve many organ systems. Clinical signs and symptoms are acute dyspnea, cough, hypotension, cyanosis, fetal bradycardia, encephalopathy, acute pulmonary hypertension, coagulopathy etc. Besides basic investigations lung scan, serum tryptase levels, serum levels of C3 and C4 complements, zinc coproporphyrin, serum sialyl Tn etc are helpful in establishing the diagnosis. Treatment is mainly supportive, but exchange transfusion, extracorporeal membrane oxygenation, and uterine artery embolization have been tried from time to time. The maternal prognosis after amniotic fluid embolism is very poor though infant survival rate is around 70%.

Amniotic Fluid Embolism: Anaphylactic Reactions With Idiosyncratic Adverse Response

PROBLEM

Amniotic fluid embolism (AFE) is a rare but severe emergency in obstetrics. The aim of the present study was to investigate the pathophysiology of AFE.

METHODS

A search was conducted between 1966 and 2014 through the English-language literature (online MEDLINE PubMed database) using the keyword amniotic fluid embolism combined with anaphylaxis, anaphylactoid, complement activation, mast cells, fetal antigens, and idiosyncratic.

RESULTS

Amniotic fluid embolism is a rare clinical entity but a severe obstetric emergency that can be lethal even in previously healthy women in labor or in the early postpartum period. There appears to be at least 2 mechanisms. First, adverse reactions in AFE are usually unexpected and fetal antigen dose dependent. Given the disastrous entry of amniotic fluid into the maternal circulation, they experience a sudden cardiopulmonary collapse (mechanical obstruction subtype). Second, anaphylactic and anaphylactoid reactions of the remaining AFE are also relatively unexpected and fetal antigen dose independent and can occur at the first exposure to amniotic fluid components. They are associated with complement activation and subsequent postpartum hemorrhage. Cardiac mast cells constitute a central pathogenesis of anaphylactic (immunoglobulin E-dependent) and anaphylactoid (immunoglobulin E-independent) reactions.

CONCLUSIONS

Recent immunologic studies provide a new approach to the study of the pathophysiology of AFE.

Evaluation of obstetrical patients with disseminated intravascular coagulopathy - tertiary center experience

OBJECTIVE

The purpose of the present study is twofold: (a) to investigate the etiology of disseminated intravascular coagulopathy (DIC) caused by obstetrical conditions and (b) to present parameters that can be used in predicting DIC-related mortality in obstetrical patients.

MATERIAL AND METHOD

Obstetrical patients who had a delivery at or were referred (after delivery) to Obstetrics and Gynecology Clinic of Dicle University between July 2006 and December 2013 were retrospectively analyzed in this study. Those patients diagnosed with DIC were included in the study.

RESULTS

Fifty-six obstetrical patients carrying the diagnosis of DIC were included in this study. The overall mortality rate was 25% among these patients. More specifically, the mortality rate was 10.7% among patients with a DIC score ≤5 and 40.7% among those with a DIC score > 5. Multiple logistic regression analysis resulted in the finding that international normalized ratio (INR) and urea were among those factors affecting mortality in obstetrical DIC [OR: 8.44 (CI: 1.9-36.8), OR: 1.05 (CI: 1.0-1.1), respectively].

CONCLUSION

DIC is a syndrome that might be caused by obstetrical conditions. It is associated with high mortality and morbidity rates. In obstetrical DIC, urea is the most important factor affecting mortality. In addition, we are of the opinion that DIC score might guide mortality predictions as a determinant of prognosis.

C1 esterase inhibitor activity in amniotic fluid embolism

OBJECTIVES

Amniotic fluid embolism exhibits activation of the complement system and the kallikrein-kinin and coagulofibrinolytic systems. C1 esterase inhibitor is a major inhibitor of C1 esterase and can inhibit plasma kallikrein and also factors XIIa and XIa. Its activity has been shown to be significantly lower in pregnancy and labor than in the nonpregnant state. The purpose of this study was to determine C1 esterase inhibitor activity levels in amniotic fluid embolism.

DESIGN

Retrospective study.

SETTING

A single university-based center.

PATIENTS

One hundred six cases with amniotic fluid embolism in a total of 194 singleton pregnant women between January 2010 and December 2011.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred six cases of amniotic fluid embolism had applied to the Japan amniotic fluid embolism registration center in Hamamatsu University School of Medicine between January 2010 and December 2011. In amniotic fluid embolism cases, 85 cases were nonfatal and 21 cases were fatal. Eighty-eight women who delivered without amniotic fluid embolism were regarded as a control. C1 esterase inhibitor activity levels were significantly lower in amniotic fluid embolism patients (30.0% ± 1.8%) than in control women (62.0% ± 2.0%) (p < 0.0001). C1 esterase inhibitor activity levels in fatal amniotic fluid embolism cases (22.5% ± 3.4%) were significantly lower than those in nonfatal amniotic fluid embolism cases (32.0% ± 2.1%) (p < 0.05).

CONCLUSIONS

These results demonstrated that low C1 esterase inhibitor activity levels were closely associated with the pathogenesis of amniotic fluid embolism suggesting that C1 esterase inhibitor activity levels have potential as a prognosis factor of amniotic fluid embolism.

Survival after an amniotic fluid embolism following the use of sodium bicarbonate

Amniotic fluid embolism (AFE) is a rare and potentially fatal complication of pregnancy. In this case report, we highlight the successful use of sodium bicarbonate in a patient with an AFE. We present a case of a 38-year-old mother admitted for an elective caesarean section. Following the delivery of her baby, the mother suffered a cardiac arrest. Following a protracted resuscitation, transoesophageal echocardiography demonstrated evidence of acute pulmonary hypertension, with an empty left ventricle and an over-distended right ventricle. In view of these findings and no improvement noted from on-going resuscitation, sodium bicarbonate was infused as a pulmonary vasodilator. Almost instantaneous return of spontaneous circulation was noted, with normalisation of cardiac parameters. We propose that in patients suspected with AFE and who have been unresponsive to advance cardiac life support measures, and where right ventricular failure is present with acidosis and/or hypercarbia, the use of sodium bicarbonate should be considered.

Incidence, diagnosis and pathophysiology of amniotic fluid embolism

Amniotic fluid embolism (AFE) is a rare clinical entity, sometimes fatal. A review was conducted to describe the frequency, diagnosis and pathophysiology of AFE. The reported incidences ranged from 1.9 cases per 100,000 maternities (UK) to 6.1 per 100,000 maternities (Australia), which can vary considerably, depending on the period, region of study and the definition. Although the development of amniotic fluid-specific markers would have an impact on early diagnosis, definition of AFE based on these markers is not widely accepted. To date, immunological mechanisms, amniotic fluid-dependent anaphylactic reaction and complement activation, have been proposed as potential pathogenetic and pathophysiological mechanisms. Immune cell activation induced through complement activation may be associated with the mechanism that immediately initiates maternal death, only in susceptible individuals. This review will focus on advances in the field of AFE biology and discuss the prevalence, diagnosis and pathophysiology of AFE.

Amniotic fluid embolism: an interdisciplinary challenge: epidemiology, diagnosis and treatment

BACKGROUND

Amniotic fluid embolism (AFE) is a life-threatening obstetric complication that arises in 2 to 8 of every 100 000 deliveries. With a mortality of 11% to 44%, it is among the leading direct causes of maternal death. This entity is an interdisciplinary challenge because of its presentation with sudden cardiac arrest without any immediately obvious cause, the lack of specific diagnostic tests, the difficulty of establishing the diagnosis and excluding competing diagnoses, and the complex treatment required, including cardio - pulmonary resuscitation.

METHOD

We selectively reviewed pertinent literature published from 2000 to May 2013 that was retrieved by a PubMed search.

RESULTS

The identified risk factors for AFE are maternal age 35 and above (odds ratio [OR] 1.86), Cesarean section (OR 12.4), placenta previa (OR 10.5), and multiple pregnancy (OR 8.5). AFE is diagnosed on clinical grounds after the exclusion of other causes of acute cardiovascular decompensation during delivery, such as pulmonary thromboembolism or myocardial infarction. Its main clinical features are severe hypotension, arrhythmia, cardiac arrest, pulmonary and neurological manifestations, and profuse bleeding because of disseminated intravascular coagulation and/or hyperfibrinolysis. Its treatment requires immediate, optimal interdisciplinary cooperation. Low-level evidence favors treating women suffering from AFE by securing the airway, adequate oxygenation, circulatory support, and correction of hemostatic disturbances. The sudden, unexplained death of a pregnant woman necessitates a forensic autopsy. The histological or immunohistochemical demonstration of formed amniotic fluid components in the pulmonary bloodflow establishes the diagnosis of AFE.

CONCLUSION

AFE has become more common in recent years, for unclear reasons. Rapid diagnosis and immediate interdisciplinary treatment are essential for a good outcome. Establishing evidence-based recommendations for intervention is an important goal for the near future.

Incidence, risk factors, and consequences of amniotic fluid embolism

BACKGROUND

Amniotic fluid embolism (AFE) is a rare but serious cause of maternal mortality whose aetiology remains obscure. Previous population-based studies have reported associations with labour induction and caesarean delivery.

METHODS

We updated a previous analysis based on the US Nationwide Inpatient Sample from 1999 to 2008. We adapted a diagnostic validation algorithm to minimise false-positive diagnoses, along with statistical methods that account for the stratified random sampling design.

RESULTS

Of the 8 571 209 deliveries recorded in the database, 276 met our case definition of AFE, of which 62 (22.9% of the 274 with known vital status) were fatal. Significant associations with AFE were observed for medical induction {adjusted odds ratio [aOR] = 1.7 [95% confidence interval (CI) 1.2, 2.5]}, caesarean delivery [aOR = 15.0; 95% CI 9.4, 23.9], instrumental vaginal delivery [aOR = 6.6; 95% CI 4.0, 11.1], and cervical/uterine trauma [aOR = 7.4; 95% CI 3.6, 14.9]. AFE was associated with increases in risk of stillbirth, hysterectomy, maternal death, and prolonged maternal length of delivery hospital stay.

CONCLUSIONS

AFE remains an extremely serious obstetric complication with high risks of maternal and fetal mortality. The increased risks of AFE associated with labour induction and caesarean delivery have implications for elective use of these interventions.

Amniotic fluid embolism

Amniotic fluid embolism (AFE) is an unpredictable and as-of-yet unpreventable complication of maternity. With its low incidence it is unlikely that any given practitioner will be confronted with a case of AFE. However, this rare occurrence carries a high probability of serious sequelae including cardiac arrest, ARDS, coagulopathy with massive hemorrhage, encephalopathy, seizures, and both maternal and infant mortality. In this review the current state of medical knowledge about AFE is outlined including its incidence, risk factors, diagnosis, pathophysiology, and clinical manifestations. Special attention is paid to the modern aggressive supportive care that resulted in an overall reduction in the still alarmingly high mortality rate of this devastating entity. The key factors for successful management and resolution of this disease process continue to be sharp vigilance, a high level of clinical suspicion, and rapid all-out resuscitative efforts on the part of all clinicians involved in the medical care of the parturient.

[Amniotic fluid embolism: an update]

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.

Fatal amniotic fluid embolism with typical pathohistological, histochemical and clinical features

Despite the decrease in maternal mortality rate, amniotic fluid embolism (AFE) is still one of the most feared complications of pregnancy due to the high rate of mortality in Japan. The authors present a fatal case of a healthy 39-year-old woman who died during delivery after a normal 40-week second pregnancy. Shortly after the arrival at hospital, an abrupt drop of foetal heart rate was observed, followed by deterioration of consciousness and cardiac arrest of the patient. Prompt cardiopulmonary resuscitation (CPR) was performed but the patient died about an hour and a half after her arrival at hospital. Forensic autopsy confirmed the pathohistological diagnosis of amniotic fluid embolism supported by histochemical analysis results and excluded other possible causes of death. This paper stresses the fundamental importance of autopsy in an unexpected maternal death in conjunction with the significance of data accumulation on maternal death.

Electrical impedance tomography may optimize ventilation in a postpartum woman with respiratory failure

Amniotic fluid embolism is a rare peripartum complication with the sudden onset of haemodynamic instability, respiratory failure and coagulopathy during labour or soon after delivery. A 31-year-old woman with amniotic fluid embolism was treated with vasopressors, inotropes, intravenous fluid, tranexamic acid and ventilatory support. Assessment of respiratory impairment was made using conventional chest X-ray, computed tomography and electrical impedance tomography. The potential for electrical impedance tomography to improve monitoring and guide respiratory therapy is explored.

Medical responsibility in the operating room: the example of an amniotic fluid embolism

Amniotic fluid embolism (AFE) continues to be one of the most feared complications of pregnancy. A healthy 32-year-old woman died during delivery after a normal 39-week third pregnancy. The family filed a complaint with a criminal court as the causes of death appeared unclear. No risk factor associated with AFE was identified. Clinical presentation was typical, including sudden onset of cardiovascular and respiratory symptoms. Autopsy confirmed the histological diagnosis of amniotic embolism and excluded an iatrogenic cause of death or anesthetic malpractice. This article highlights the value of both antemortem records and histological features in establishing the diagnosis of AFE and demonstrates the fundamental importance of autopsy in an unexpected death related directly or indirectly to a medical procedure.

Perinatal morbidity and risk of hypoxic-ischemic encephalopathy associated with intrapartum sentinel events

OBJECTIVE

To examine perinatal morbidity and rate of hypoxic-ischemic encephalopathy in infants exposed to intrapartum sentinel events.

STUDY DESIGN

Retrospective cohort study from 2000-2005. Perinatal mortality, perinatal morbidity and rate of hypoxic-ischemic encephalopathy were compared in 3 groups of infants exposed to different risk factors for perinatal asphyxia (sentinel events, nonreassuring fetal status, elective cesarean section).

RESULTS

Five hundred eighty-six infants were studied. Perinatal mortality was 6% in the sentinel event group and 0.3% in the nonreassuring fetal status group (relative risk, 2.4; 95% confidence interval, 1.95-2.94). Perinatal morbidity was 2-6 times more frequent in infants exposed to sentinel events; the incidence of hypoxic-ischemic encephalopathy was 10%, compared with 2.5% in the nonreassuring fetal status group (relative risk, 1.93; 95% confidence interval, 1.49-2.52). No infant in the elective cesarean section group died, had perinatal morbidity, or developed encephalopathy.

CONCLUSION

Intrapartum sentinel events are associated with a high incidence of perinatal morbidity and hypoxic-ischemic encephalopathy.

Current concepts of immunology and diagnosis in amniotic fluid embolism

Amniotic fluid embolism (AFE) is one of the leading causes of maternal mortality and morbidity in developed countries. Current thinking about pathophysiology has shifted away from embolism toward a maternal immune response to the fetus. Two immunologic mechanisms have been studied to date. Anaphylaxis appears to be doubtful while the available evidence supports a role for complement activation. With the mechanism remaining to be elucidated, AFE remains a clinical diagnosis. It is diagnosed based on one or more of four key signs/symptoms: cardiovascular collapse, respiratory distress, coagulopathy, and/or coma/seizures. The only laboratory test that reliably supports the diagnosis is the finding of fetal material in the maternal pulmonary circulation at autopsy. Perhaps the most compelling mystery surrounding AFE is not why one in 20,000 parturients are afflicted, but rather how the vast majority of women can tolerate the foreign antigenic presence of their fetus both within their uterus and circulation?

Successful recovery from delayed amniotic fluid embolism with prolonged cardiac resuscitation

Amniotic fluid embolisms (AFE) are one of the most fatal complications of pregnancy. We describe a case of AFE that occurred 2 h after vaginal delivery at 41 weeks of gestation. The diagnosis of AFE was made by symptoms of dyspnea, coagulopathy, and severe hypotension. ZnCP-1, the characteristic component of meconium, was elevated in the serum. Cardiac compressions after repeated cardiac arrests were required during the initial 2 h of resuscitation. Primary resuscitation was performed with airway management and aggressive fluid management, including infusion of 33 units of red cell concentrates and 57 units of fresh frozen plasma. The patient recovered without any aftereffects. This case report warrants that AFE should be considered when coagulopathy and dyspnea are observed during the postpartum period.

Amniotic fluid embolism

Amniotic fluid embolism (AFE) remains an enigmatic, but devastating obstetrical condition associated with significant maternal and newborn morbidity and mortality. Although our understanding of this condition is incomplete, research over the past 2 decades has altered traditional concepts of both the causation and pathophysiology of AFE. Although maternal treatment remains primarily supportive, prompt delivery of the fetus can substantially improve neonatal outcome after AFE-induced cardiac arrest. Newer biochemical markers may in the future enhance the specificity and sensitivity of this clinical diagnosis and could potentially lead to improved therapy.

Amniotic fluid embolism: an evidence-based review

We conducted an evidence-based review of information about [corrected] amniotic fluid embolism (AFE). The estimated incidence of AFE is 1:15,200 and 1:53,800 deliveries in North America and Europe, respectively. The case fatality rate and perinatal mortality associated with AFE are 13-30% and 9-44%, respectively. Risk factors associated with an [corrected] increased risk of AFE include advanced maternal age, placental abnormalities, operative deliveries, eclampsia, polyhydramnios, cervical lacerations, [corrected] and uterine rupture. The hemodynamic response in [corrected] AFE is biphasic, with initial pulmonary hypertension and right ventricular failure, followed by left ventricular failure. Promising therapies include selective pulmonary vasodilators and recombinant activated factor VIIa. Important topics for future research are presented.

Responding to amniotic fluid embolism

Amniotic fluid embolism (AFE), an uncommon disorder with a high fatality rate, is an obstetric emergency that requires swift recognition and intervention to save both the mother's life and that of her child.The high mortality rate and varying theories as to its cause make it difficult to diagnose AFE, which can occur at any point during labor and delivery, including during cesarean birth. These factors make it important for perioperative nurses to understand and recognize AFE when it occurs in the OR. Rapid delivery of the fetus is imperative for the survival of both mother and child. Monitoring and aggressively providing respiratory and circulatory support interventions are required if the mother is to survive AFE.