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

Prognostic Role of Initial Thromboelastography in Emergency Department Patients with Primary Postpartum Hemorrhage: Association with Massive Transfusion

BACKGROUND

The early prediction of the need for massive transfusions (MTs) and the preparation of blood products are essential for managing patients with primary postpartum hemorrhage (PPH). Thromboelastography (TEG) enables a thorough evaluation of coagulation status and is useful for guiding the treatment of hemorrhagic events in various diseases. We investigated the role of TEG in predicting the need for MT in patients with primary PPH.

METHODS

A retrospective observational study was conducted in the emergency department (ED) of a university-affiliated, tertiary referral center between November 2015 and August 2023. TEG was performed upon admission. We defined MT as the requirement for transfusion of more than 10 units of packed red blood cells within the first 24 h. The primary outcome was the need for MT.

RESULTS

Among the 184 patients with initial TEG, 34 (18.5%) required MT. Except for lysis after 30 min, the MT and non-MT groups had significantly different TEG values. Based on multivariate analysis, an angle < 60 was an independent predictor of MT (odds ratio (OR) 7.769; 95% confidence interval (CI), 2.736-22.062), along with lactate (OR, 1.674; 95% CI, 1.218-2.300) and shock index > 0.9 (OR, 4.638; 95% CI, 1.784-12.056). Alpha angle < 60 degrees indicated the need for MT with 73.5% sensitivity, 72.0% specificity, and 92.3% negative predictive value.

CONCLUSIONS

Point-of-care testing of TEG has the potential to be a useful tool in accurately predicting the necessity for MT in ED patients with primary PPH at an early stage.

[Maternal mortality due to Amniotic Fluid Embolism in France 2016-2018]

Amniotic embolism remains the 3rd leading cause of maternal death in France, with 21 maternal deaths over the 2016-2018 triennium. The women who died were more likely to be obese (25%), to benefit from induction of labor (71%) and be cared in a maternity hospital <1500 deliveries/year (45%), compared with the reference population (ENP 2016). The symptom occurred mainly during labor (95%) and the course was rapid, with a symptom-to-fatality interval of 4hours 45minutes (min: 25minutes - max: 8 days). Preventability was proposed for 35% of the deaths assessed, with areas for improvement identified in terms of technical skills (haemostasis procedures, management of polytransfusion), non-technical skills (communication) and health care organization (human resources, vital emergency plan, wide access to PSL). An autopsy was performed in 38% of deaths.

Amniotic fluid embolism: 20-year incidence and case-fatality trends in the United States

OBJECTIVE

To estimate incidence and case-fatality rates of amniotic fluid embolism (AFE) and to examine their temporal trends.

STUDY DESIGN

Population-based retrospective cohort study using the 2000-2019 Health Care Cost and Utilization Project, Nationwide Inpatient Sample (HCUP-NIS). Annual population rates were estimated using HCUP-NIS specific weighting. Descriptive analyses and logistic regression described trends within the cohort.

RESULTS

Over the study period, AFE incidence rate remained stable (mean 4.9 cases/100,000 deliveries) and the case-fatality rate declined (mean 17.7 %,95 % CI 16.40-10.09). Highest AFE incidence rates and fatality rates were in women ≥ 35 years, African-Americans, and in urban-teaching hospitals. AFE mortality rates decreased among Hispanics.

CONCLUSION

AFE rates remained stable and fatality rates declined over time. Highest rates of AFE occurrence and death were in women who typically have greater risk of experiencing adverse obstetrical outcomes. Continued research into early diagnostic methods and effective treatments are needed to further improve AFE incidence and mortality rates.

Amniotic fluid embolism: a reappraisal

OBJECTIVES

Using cases from our own experience and from the published literature on amniotic fluid embolism (AFE), we seek to improve on existing criteria for diagnosis and discern associated risk factors. Additionally, we propose a novel theory of pathophysiology.

METHODS

This retrospective case review includes eight cases of AFE from two hospital systems and 21 from the published literature. All cases were evaluated using the modified criteria for research reporting of AFE by Clark et al. in Am J Obstet Gynecol, 2016;215:408-12 as well as our proposed criteria for diagnosis. Additional clinical and demographic characteristics potentially correlated with a risk of AFE were included and analyzed using descriptive analysis.

RESULTS

The incidence of AFE was 2.9 per 100,000 births, with five maternal deaths in 29 cases (17.2 %) in our series. None of the cases met Clark's criteria while all met our criteria. 62.1 % of patients were over the age of 32 years and two out of 29 women (6.9 %) conceived through in-vitro fertilization. 6.5 % of cases were complicated by fetal death. Placenta previa occurred in 13.8 %. 86.2 % of women had cesarean sections of which 52.0 % had no acute maternal indication.

CONCLUSIONS

Our criteria identify more patients with AFE than others with a low likelihood of false positives. Clinical and demographic associations in our review are consistent with those previously reported. A possible relationship between cesarean birth and risk of AFE was identified using our criteria. Additionally, we propose a new hypothesis of pathophysiology.

Extracorporeal Cardiopulmonary Resuscitation for Amniotic Fluid Embolism: Review and Case Report

ABSTRACT

Amniotic fluid embolism (AFE) is a rare, sudden, and catastrophic complication of pregnancy that can result in cardiopulmonary arrest, potentially leading to death. The pathophysiology of an AFE includes an inflammatory and coagulopathic response due to fetal materials entering maternal circulation with the hallmark triad of symptoms: acute respiratory distress, cardiovascular collapse, and coagulopathy. Management of AFE should include high-quality cardiopulmonary resuscitation, immediate delivery of the fetus if applicable, early intubation to provide adequate oxygenation and ventilation, fluid volume resuscitation, and ongoing evaluation of coagulopathy. Priorities include thromoboelastography interpretation if available, control of hemorrhage and coagulopathy with blood component therapy, and cardiovascular support through inotropes and vasopressor administration. More recent approaches include implementing the A-OK (atropine, ondansetron, and ketorolac) protocol for suspected AFE protocol, extracorporeal cardiopulmonary resuscitation (ECPR), and extracorporeal membrane oxygenation (ECMO) therapies to increase survival and decrease complications. Venoarterial ECMO is the highest form of life support that provides support in patients with pulmonary and cardiac failure. ECPR is the application of Venoarterial ECMO during cardiopulmonary resuscitation in cases where the cause of arrest is believed to be reversible. Early implementation of ECPR during the acute phase of AFE can provide support for end-organ perfusion in place of the weakened and recovering heart while optimizing oxygenation, making venoarterial ECMO an ideal adjunctive therapy. Because of the rarity of AFE, many obstetrical teams may have limited prior experience in managing these catastrophic cases; however, with ongoing education and simulation, teams can be better prepared in the recognition and management of these life-threatening events.

Massive platelet-rich thrombus formation in small pulmonary vessels in amniotic fluid embolism: An autopsy study

OBJECTIVE

To identify pulmonary/uterine thrombus formation in amniotic fluid embolism (AFE).

DESIGN

Retrospective, observational.

SETTING

Nationwide.

POPULATION

Eleven autopsy cases of AFE and control cases.

METHODS

We assessed pulmonary and uterine thrombus formation and thrombus area in AFE and pulmonary thromboembolism (PTE) as a control. The area of platelet glycoprotein IIb/IIIa, fibrin, neutrophil elastase, citrullinated histone H3 (a neutrophil extracellular trap marker) and mast cell chymase immunopositivity was measured in 90 pulmonary emboli, 15 uterine thrombi and 14 PTE.

MAIN OUTCOME MEASURES

Pathological evidence of thrombus formation and its components in AFE.

RESULTS

Amniotic fluid embolism lung showed massive thrombus formation, with or without amniotic emboli in small pulmonary arteries and capillaries. The median pulmonary thrombus size in AFE (median, 0.012 mm2 ; P < 0.0001) was significantly smaller than that of uterine thrombus in AFE (0.61 mm2 ) or PTE (29 mm2 ). The median area of glycoprotein IIb/IIIa immunopositivity in pulmonary thrombi in AFE (39%; P < 0.01) was significantly larger than that of uterine thrombi in AFE (23%) and PTE (15%). The median area of fibrin (0%; P < 0.001) and citrullinated histone H3 (0%; P < 0.01) immunopositivity in pulmonary thrombi in AFE was significantly smaller than in uterine thrombi (fibrin: 26%; citrullinated histone H3: 1.1%) and PTE (fibrin: 42%; citrullinated histone H3: 0.4%). No mast cells were identified in pulmonary thrombi.

CONCLUSIONS

Amniotic fluid may induce distinct thrombus formation in the uterus and lung. Pulmonary and uterine thrombi formation may contribute to cardiorespiratory collapse and/or consumptive coagulopathy in AFE.

Coagulation management and transfusion in massive postpartum hemorrhage

PURPOSE OF REVIEW

Excessive bleeding during and following childbirth remains one of the leading causes of maternal mortality.

RECENT FINDINGS

Current guidelines differ in definitions and recommendations on managing transfusion and hemostasis in massive postpartum hemorrhage (PPH). Insights gained from trauma-induced coagulopathy are not directly transferable to the obstetric population due to gestational alterations and a differing pathophysiology.

SUMMARY

Factor deficiency is uncommon at the beginning of most etiologies of PPH but will eventually develop from consumption and depletion in the absence of bleeding control. The sensitivity of point-of-care tests for fibrinolysis is too low and may delay treatment, therefore tranexamic acid should be started early at diagnosis even without signs for hyperfibrinolysis. Transfusion management may be initiated empirically, but is best to be guided by laboratory and viscoelastic assay results as soon as possible. Hypofibrinogenemia is well detected by point-of-care tests, thus substitution may be tailored to individual needs, while reliable thresholds for fresh frozen plasma (FFP) and specific components are yet to be defined. In case of factor deficiency, prothrombin complex concentrate or lyophilized plasma allow for a more rapid restoration of coagulation than FFP. If bleeding and hemostasis are under control, a timely anticoagulation may be necessary.

Amniotic Fluid Embolism: a comparison of two classification systems in a retrospective 8-year analysis from two tertiary hospitals

OBJECTIVE

Amniotic fluid embolism (AFE) is a rare life-threatening complication in obstetrics, but the diagnosis lacks a consensual definition. The objective of this study was to compare two different AFE classification systems by analysing the AFE cases from two university hospitals.

MATERIAL AND METHODS

In this retrospective study, all patients with a strong suspicion of AFE between 2014 and 2021 at two university hospitals, LMU Women's University Hospital Munich, and Women's University Hospital Basel, were included. Patient records were checked for the ICD-10 code O88.1 (AFE). Diagnoses were confirmed through clinical findings and/or autopsy. The presence of the diagnostic criteria of the Society of Maternal Fetal Medicine (SMFM) and the AFE Foundation (AFEF) and of a new framework by Ponzio-Klijanienko et al. from Paris, France, were checked and compared using Chi-square-test.

RESULTS

Within our study period, 38,934 women delivered in the two hospitals. Six patients had a strong suspicion of AFE (0.015%). Only three of six patients (50%) presented with all the four diagnostic criteria of the SMFM/AFEF framework. All six patients met the criteria of the modified "Paris AFE framework".

CONCLUSION

Using the "Paris AFE framework" based exclusively on clinical criteria can help clinicians to diagnose AFE, anticipate the life-threatening condition of the patient and prepare immediately for best clinical care.

Anaphylaxis in Pregnancy

Anaphylaxis in pregnancy is a rare event, but has important implications for the pregnant patient and fetus. The epidemiology, pathophysiology, diagnosis, and treatment all carry important considerations unique to the pregnant patient. Common culprits of anaphylaxis are primarily medications, particularly antibiotics and anesthetic agents. Diagnosis can be difficult given the relative lack of cutaneous symptoms, and normal physiologic changes in pregnancy such as low blood pressure and tachycardia. Apart from patient positioning, treatment is similar to that of the general population, with a focus on prompt epinephrine administration.

What Is New in Obstetric Anesthesia: The 2021 Gerard W. Ostheimer Lecture

The Gerard W. Ostheimer lecture is given annually to members of the Society for Obstetric Anesthesia and Perinatology. This lecture summarizes new and emerging literature that informs the clinical practice of obstetric anesthesiologists. In this review, some of the most influential articles discussed in the 2021 virtual lecture are highlighted. Themes include maternal mortality; disparities and social determinants of health; cognitive function, mental health, and recovery; quality and safety; operations, value, and economics; clinical controversies and dogmas; epidemics and pandemics; fetal-neonatal and child health; general clinical care; basic and translational science; and the future of peripartum anesthetic care. Practice-changing evidence is presented and evaluated. A priority list for clinical updates, systems, and quality improvement initiatives is presented.

Point-of-care coagulation testing for postpartum haemorrhage

The use of viscoelastic haemostatic assays (VHAs) to guide blood product replacement during postpartum haemorrhage is expanding. Rotem and TEG devices can be used to detect and treat clinically significant hypofibrinogenaemia, although evidence to support the role of VHAs for guiding fresh frozen plasma and platelet transfusion is less clear. If Rotem/TEG traces are normal, clinicians should investigate for another cause of bleeding, and haemostatic support is not required. Guidelines support the use of VHAs during postpartum haemorrhage as part of locally agreed algorithms. There is a wide consensus that fibrinogen replacement is needed if the Fibtem A5 is <12 mm and if there is ongoing bleeding. Guidelines recommend against using VHAs to guide tranexamic acid infusion, and this drug should be given as soon as bleeding is recognised, irrespective of the Rotem/TEG traces. The cost-effectiveness of VHAs during postpartum haemorrhage needs to be addressed.

Association of Pregnancy Characteristics and Maternal Mortality With Amniotic Fluid Embolism

IMPORTANCE

Amniotic fluid embolism (AFE) is an uncommon pregnancy complication but is associated with high maternal mortality. Because of the rarity of AFE, associated risks factors and maternal outcomes have been relatively understudied.

OBJECTIVE

To examine the clinical, pregnancy, and delivery characteristics and the maternal outcomes related to AFE in a recent period in the US.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study examined hospital deliveries from January 1, 2016, to December 31, 2019, from the Healthcare Cost and Utilization Project's National Inpatient Sample.

MAIN OUTCOMES AND MEASURES

The primary outcome was clinical, pregnancy, and delivery characteristics of AFE, assessed with a multivariable binary logistic regression model. The coprimary outcome was failure to rescue, defined as maternal mortality after AFE. Associations with other severe maternal morbidity indicators and failure to rescue per clinical and pregnancy characteristics were also assessed.

RESULTS

A total of 14 684 135 deliveries were examined, with AFE diagnosed in 880 women, corresponding to an incidence rate of 6.0 per 100 000 deliveries. The cohort-level median patient age was 29 years (IQR, 25-33 years). In a multivariable analysis, (1) patient factors of older age, Asian and Black race, Western US region, pregestational hypertension, asthma, illicit substance use, and grand multiparity; (2) pregnancy factors of placental accreta spectrum (PAS), placental abruption, uterine rupture, polyhydramnios, chorioamnionitis, preeclampsia, fetal growth restriction, and fetal demise; and (3) delivery factors of early gestational age, cervical ripening, cesarean delivery, operative delivery, and manual removal were associated with AFE. Among these characteristics, PAS had the largest association with AFE (adjusted odds ratio [aOR], 10.01; 95% CI, 7.03-14.24). When stratified by the PAS subtypes, more severe forms of PAS had a greater association with AFE (aOR for increta and percreta, 17.35; 95% CI, 10.21-28.48; and aOR for accreta, 7.62; 95% CI, 4.83-12.01). Patients who had AFE were more likely to have coagulopathy (aOR, 24.68; 95% CI, 19.38-31.44), cardiac arrest (aOR, 24.56; 95% CI, 17.84-33.81), and adult respiratory distress syndrome (aOR, 10.72; 95% CI, 8.09-14.20). The failure-to-rescue rate after AFE was 17.0% overall. However, the failure-to-rescue rate exceeded 30% when AFE co-occurred with other severe maternal morbidity indicators: 45.8% for AFE, cardiac arrest, and coagulopathy; 43.2% for AFE, shock, and cardiac rhythm conversion; and 38.6% for AFE, cardiac arrest, coagulopathy, and shock. The failure-to-rescue rate after AFE also exceeded 30% when AFE occurred in the setting of placental pathology: 42.9% for AFE and PAS and 31.3% for AFE and placental abruption.

CONCLUSIONS AND RELEVANCE

This contemporaneous, national-level analysis validated previously known risk factors for AFE and confirmed the dismal outcomes of pregnancy complicated by AFE. The association between PAS and AFE, which was not previously reported, warrants further investigation.

Pulmonary Embolism and Amniotic Fluid Embolism

Venous thromboembolism (VTE) as well as other embolic events including amniotic fluid embolism (AFE) remain a leading cause of maternal death in the United States and worldwide. The pregnant patient is at a higher risk of developing VTE including pulmonary embolism. In contrast, AFE is a rare, but catastrophic event that remains incompletely understood. Here the authors review the cause of VTE in pregnancy and look at contemporary and evidence-based practices for the evaluation, diagnosis, and management in pregnancy. Then the cause and diagnostic difficulty of AFE as well as what is known regarding the pathogenesis are reviewed.

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.

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.

Society for Maternal-Fetal Medicine Special Statement: Checklist for initial management of amniotic fluid embolism

Amniotic fluid embolism is a rare syndrome characterized by sudden cardiorespiratory collapse during labor or soon after delivery. Because of its rarity, many obstetrical providers have no experience in managing amniotic fluid embolism and may therefore benefit from a cognitive aid such as a checklist. We present a sample checklist for the initial management of amniotic fluid embolism based on standard management guidelines. We also suggest steps that each facility can take to implement the checklist effectively.

Use and Interpretation of Acute and Baseline Tryptase in Perioperative Hypersensitivity and Anaphylaxis

Paired acute and baseline serum or plasma tryptase sampling and determination have recently been included as a mechanistic approach in the diagnostic and management guidelines of perioperative immediate hypersensitivity and anaphylaxis. The timing of this paired sampling is clearly defined in international consensus statements, with the optimal window for acute tryptase sampling between 30 minutes and 2 hours after the initiation of symptoms, whereas baseline tryptase should be measured in a sample collected before the event (preop) or at least 24 hours after all signs and symptoms have resolved. A transient elevation of the acute tryptase level greater than [2 + (1.2 × baseline tryptase level)] supports the involvement and activation of mast cells. Here, we provide the clinical, pathophysiological, and technical rationale for the procedure and interpretation of paired acute and baseline tryptase. Clinical examples, up-to-date knowledge of hereditary α-tryptasemia as a frequent cause of baseline tryptase of 7 μg/L and higher, mastocytosis, other clonal myeloid disorders, cardiovascular or renal failure, and technical improvements resulting in continued lowering of the 95th percentile value are discussed. Clues for improved management of perioperative immediate hypersensitivity and anaphylaxis include (1) sustained dissemination and implementation of updated guidelines; (2) preoperative sample storage for deferred analysis; (3) referral for thorough allergy investigation, screening for mast cell-related disorders, and recommendations for future anesthetic procedures; and (4) sustained collaboration between anesthesiologists, immunologists, and allergists.