A fatal case of amniotic fluid embolism with elevation of serum mast cell tryptase

Fatal anaphylactic shock: A review of postmortem biomarkers and diagnostics

Diagnosing anaphylactic shock postmortem is challenging since differential diagnoses exist and the forensic pathologist often faces subtle findings and lacks relevant information which prevents reaching an opinion of certainty. This review provides an overview of the literature covering research and existing recommendations on the postmortem diagnosis of anaphylactic shock. In order to harmonize the approach and provide guidance for diagnosing deaths from anaphylactic shock in the six forensic centers in Sweden, a guidance protocol aligned with the notion of a holistic view in the approach was devised. Areas in need of further studies include both immunohistological and biochemical investigations to stratify quantitative approaches based on condition and anaphylactic trigger and to lay the ground for and possibly establish alternative matrices.

Amniotic fluid embolism complicating medical termination of pregnancy

BACKGROUND

Amniotic fluid embolism is always a severe complication and generally occurs during labour or immediately after childbirth.

CLINICAL FEATURES

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. The amniotic fluid embolism diagnosis was strongly suspected in the face of the sudden onset of severe arterial hypotension, hypoxic respiratory distress, a coma state and disseminated intravascular coagulopathy immediately after the delivery. Additional tests were conducted to support the diagnosis: cytological testing of a peripheral venous sample and maternal broncho-alveolar lavage fluid, dosing of tryptase and alpha-fetoprotein levels as well as screening for insulin-like growth factor binding protein 1.

CONCLUSION

Amniotic fluid embolism is a rare and difficult diagnosis, especially in unconventional settings, yet it can be facilitated by screening for amniotic markers and tryptase.

Amniotic fluid embolism pathophysiology suggests the new diagnostic armamentarium: β-tryptase and complement fractions C3-C4 are the indispensable working tools

Amniotic fluid embolism (AFE) is an uncommon obstetric condition involving pregnant women during labor or in the initial stages after delivery. Its incidence is estimated to be around 5.5 cases per 100,000 deliveries. Therefore, this paper investigated the pathophysiological mechanism, which underlies AFE, in order to evaluate the role of immune response in the development of this still enigmatic clinical entity. The following databases (from 1956 to September 2014) Medline, Cochrane Central, Scopus, Web of Science and Science Direct were used, searching the following key words: AFE, pathophysiology, immune/inflammatory response, complement and anaphylaxis. The main key word “AFE” was searched singularly and associated individually to each of the other keywords. Of the 146 sources found, only 19 were considered appropriate for the purpose of this paper. The clinical course is characterized by a rapid onset of symptoms, which include: acute hypotension and/or cardiac arrest, acute hypoxia (with dyspnoea, cyanosis and/or respiratory arrest), coagulopathies (disseminated intravascular coagulation and/or severe hemorrhage), coma and seizures. The pathology still determines a significant morbidity and mortality and potential permanent neurological sequelae for surviving patients. At this moment, numerous aspects involving the pathophysiology and clinical development are still not understood and several hypotheses have been formulated, in particular the possible role of anaphylaxis and complement. Moreover, the detection of serum tryptase and complement components and the evaluation of fetal antigens can explain several aspects of immune response.

Pulmonary and coronary foreign particle embolism after central venous injection of liquid nutrition

A man was found dead in his nursing bed. The responsible assistant nurse explained that she had administered liquid nutrition (Isosource Energy Fibre 500 ml) via perfusion pump into the Hickman catheter, insisting that the Hickman catheter was a percutaneous endoscopic gastric tube. Autopsy findings were unspecific and could not reveal the cause of death. Histopathological examinations showed severe pulmonary foreign particle emboli, partially even emboli of the small coronary arteries. We present the pathological findings of the case in regard to the underlying pathophysiology.

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: the known and not known

Amniotic fluid embolism was first recognized in 1926, in a Brazilian journal case report, on the basis of large amounts of fetal material in the maternal pulmonary vasculature at autopsy. The first English language description appeared in 1941 and consisted of eight parturients dying suddenly in which, once again, fetal material was seen in the pulmonary vasculature. A control group of 34 pregnant women dying of other recognized causes did not have fetal material in their lungs. The incidence of recognized, serious illness is on the order of two to eight per 100,000, with a mortality rate ranging from 13% to 35%. The diagnosis rests largely on one or more of four clinical signs: circulatory collapse, respiratory distress, coagulopathy, and seizures/ coma. The only confirmatory laboratory test remains autopsy findings although serum tests for fetal antigen, insulin-like growth factor binding protein-1, and complement are currently being investigated. One of the paradoxes of diagnosis is that fetal material in the pulmonary circulation at autopsy is specific for amniotic fluid embolism, while the same finding in the living is not. The mechanism of disease remains uncertain although the best available evidence suggests that complement activation might have a role. In contrast, mast cell degranulation probably is not a mechanism, so amniotic fluid embolism is not an anaphylaxis or anaphylactoid reaction as has been occasionally suggested. Perhaps the greatest unknown is not why 1 in 50,000 pregnant women develop what appears to be an immune response to their fetus, but rather why the other 49,999 do not?

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.

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.

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?

Tryptase as an inflammatory marker in allergic disease and asthma

Asthma is a chronic inflammatory disease of the airways, varying from occasional episodes of wheezing and shortness of breath, to an irreversible, life-threatening obstructive disease. While many cases are managed with relative ease, others do not respond to the traditional inhaled therapy or even to oral glucocorticosteroids. Although it cannot be cured as yet, asthma can be controlled if properly diagnosed. Usually, functional clinical parameters form the basis for estimation of the disease severity. In addition, the growing database of cytokine and mediator profiles have allowed their exploitation as molecular markers for processes underlying airway inflammation in asthma. Tryptase is a potent and versatile mediator in allergic inflammation, orchestrating both acute and chronic events by acting on a vast array of cells and tissue components. For more than a decade, tryptase has been used as a marker for allergic inflammation in asthma as well as in a variety of other airway diseases. In this review, the current advantages and disadvantages of the use of tryptase as an inflammatory marker in asthma will be discussed.

Death due to blood transfusion-induced anaphylactic shock: A case report

In medical practice, many clinical accidents due to blood transfusion reactions have been reported, among which, nonhemolytic transfusion reactions (NHTRs) have been mainly reported in recent years. NHTRs induce reactions such as anaphylactic shock and transfusion-related acute lung injury (TRALI); however, few forensic autopsy case reports with blood transfusion reactions including anaphylactic shock have been published. A marker for anaphylactic shock is serum tryptase, which indicates systematic mast cell activation in living patients. In forensic medicine, serum tryptase has been used in the postmortem diagnosis of anaphylactic shock. In this autopsy case report, the blood tryptase level was elevated to 49.0 ng/mL (reference standard level <13.5 ng/mL). When considered comprehensively with autopsy findings and blood typing, we concluded that this patient was suspected to have suffered from anaphylactic shock as a result of blood transfusion.

Maternal death following cardiopulmonary collapse after delivery: amniotic fluid embolism or septic shock due to intrauterine infection?

PROBLEM

The amniotic fluid embolism (AFE) syndrome is a catastrophic complication of pregnancy frequently associated with maternal death. The causes and mechanisms of disease responsible for this syndrome remain elusive.

METHOD OF STUDY

We report two cases of maternal deaths attributed to AFE: (1) one woman presented with spontaneous labor at term, developed intrapartum fever, and after delivery had sudden cardiovascular collapse and disseminated intravascular coagulation (DIC), leading to death; (2) another woman presented with preterm labor and foul-smelling amniotic fluid, underwent a Cesarean section for fetal distress, and also had postpartum cardiovascular collapse and DIC, leading to death.

RESULTS

Of major importance is that in both cases, the maternal plasma concentration of tumor necrosis factor-alpha at the time of admission to the hospital and when patients had no clinical evidence of infection was in the lethal range (a lethal range is considered to be above 0.1 ng/mL).

CONCLUSION

We propose that subclinical intraamniotic infection may be a cause of postpartum cardiovascular collapse and DIC and resemble AFE. Thus, some patients with the clinical diagnosis of AFE may have infection/systemic inflammation as a mechanism of disease. These observations have implications for the understanding of the mechanisms of disease of patients who develop cardiovascular collapse and DIC, frequently attributed to AFE. It may be possible to identify a subset of patients who have biochemical and immunological evidence of systemic inflammation at the time of admission, and before a catastrophic event occurs.

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.

Mast cell tryptase in a case of anaphylaxis due to repeat antibiotic exposure

Mast cell tryptase can be an indicator of type I hypersensitivity reaction and thus may serve as a surrogate marker of anaphylaxis. A 34-year-old white male patient presented with a history of systemic lupus erythematosus. Shortly after administration of cefazolin for dialysis, he developed pruritus and shortness of breath. He expired an hour later. Autopsy excluded anatomic causes of death. There was an elevated postmortem mast cell tryptase level, 29.2 ng/mL. For mast cell tryptase level to be useful, the patient must survive long enough after exposure to an allergen for mast cells to release this enzyme. A credible allergen must be identified. In this case such, mast cell tryptase could establish anaphylaxis as the cause of death. The case suggests that in a patient with autoimmune disease, it may be prudent to test for immune reaction to a drug before administering it a second time via pinprick or other method.

Amniotic fluid embolism

Amniotic fluid embolism is one of the most catastrophic complications of pregnancy. First described in 1941, the condition is exceedingly rare and the exact pathophysiology is still unknown. The etiology was thought to be embolic in nature, but more recent evidence suggests an immunologic basis. Common presenting symptoms include dyspnea, nonreassuring fetal status, hypotension, seizures, and disseminated intravascular coagulation. Early recognition of amniotic fluid embolism is critical to a successful outcome. However, despite intensive resuscitation, outcomes are frequently poor for both infant and mother. Recently, aggressive and successful management of amniotic fluid embolism with recombinant factor VIIa and a ventricular assist device, inhaled nitric oxide, cardiopulmonary bypass and intraaortic balloon pump with extracorporeal membrane oxygenation have been reported and should be considered in select cases.

Complement C3a expression and tryptase degranulation as promising histopathological tests for diagnosing fatal amniotic fluid embolism

To date, the most recent specific diagnostic investigations for amniotic fluid embolism have been unable to conclusively identify any mechanism of disease other than a physical block to the circulation. We selected eight fatal cases in previously healthy women with uneventful singleton term pregnancies who presented to tertiary care centers in Italy for delivery. Pathologic features were assessed immunohistochemically using anti-fibrinogen, anti-tryptase, anti-C(3a), and anti-cytokeratin antibodies. AE1/AE3 cytokeratin stains proved positive, and tryptase-positive material was documented outside pulmonary mast cells. In all studied cases, expression of complement C(3a) was twofold lower than in the control group, suggesting a possible complement activation in AFE, initiated by fetal antigen leaking into the maternal circulation.

An autopsy case of asthmatic death--usefulness of biochemical examination

BACKGROUND

Asthma is the one of the major causes of sudden death in Japan. Postmortem diagnosis of asthma has been based on morphological findings in lungs, but it histological evidence, was also reported that the biochemical markers such as total and specific immunoglobulin E (IgE) are useful.

CASE REPORT

We present here a case of fatal asthmatic death. A Japanese male in his thirties, complaining of dyspnea, collapsed suddenly. He was taken by ambulance to hospital, but cardiopulmonary resuscitation was ineffective. From autopsy findings, we concluded that the cause of death was asphyxia due to asthma attack. Biochemical findings indicated that the deceased had a severe asthmatic condition.

CONCLUSION

In the presented case, the biochemical examination of the serum obtained at autopsy gave helpful information for the diagnosis that asthmatic attack was a cause of death.

Anaphylactic latex reaction during anaesthesia: the silent culprit in a fatal case

The true incidence of anaphylactic latex reactions and their associated morbidity and mortality remain poorly defined. It is noteworthy that a number of groups of individuals are at risk for anaphylactic reactions to latex during surgical and medical procedures; one of these groups is represented by the obstetric and gynaecologic population. A case of unrecognized first anaphylactic reaction to latex in a pregnant woman patient who underwent a caesarean section is presented. The diagnosis of latex allergy was missed and the following day the woman underwent a surgical re-exploration complicated by fatal cardiovascular arrest. At post-mortem examination, pulmonary mast cells in the bronchial walls and capillary septa were identified and a great number of degranulating mast cells with tryptase-positive material outside the cells was documented. A post-mortem latex-specific IgE test showed a high titre (14.00 U/I). Latex-induced fatal anaphylactic shock was recorded as the cause of death. This case highlights some of the practical difficulties in the initial diagnosis and subsequent investigation of fatal anaphylactic reaction during anaesthesia. Anaphylaxis is often misdiagnosed because many other pathologic conditions may present identical clinical manifestations, so anaphylactic shock must be differentiated from other causes of circulatory collapse. Although latex allergy usually has a delayed onset after the start of the surgery and most often a slow onset too, it should be always suspected if circulatory collapse and respiratory failure occur during surgery, even if the patient does not belong to a risk group; in the presence of identified risk factors for latex allergy a well-founded suspicion must be stronger, leading to an immediate discontinuation of the potential trigger.

Forensic Lung Pathology

Sudden and unexpected natural deaths and nonnatural deaths may result from various pulmonary conditions. Additionally, several nonpulmonary conditions of forensic significance may be complicated by the development of respiratory lesions. Certain situations with pulmonary pathology are particularly likely to be critically scrutinized and may form the basis of allegations of medical negligence, other personal injury liability, or wrongful death.1

A hypothesis regarding complement activation and amniotic fluid embolism

Amniotic fluid embolism, a rare, sudden and often fatal illness of pregnancy may not be a true embolic event resulting from the physical obstruction of the pulmonary vasculature. The high degree of variability in symptoms, the lack of characteristic findings on radiological exam, the absence of a dose-response effect on symptoms, and the occasional occurrence of coagulopathies are not entirely consistent with a physical block to the circulation as the main mechanism of disease. Alternatively, it might be the result of complement activation initiated by fetal antigen leaking into the maternal circulation. This rare immune response may be initiated by a rare pathological antigen, or by common antigens presented uncommonly--in amount, timing, or frequency of entry into the maternal circulation. Some very early evidence in AFE patients supports this hypothesis but is not conclusive. Complement levels remain well within the normal range during uncomplicated parturition. A prior theory that AFE might be a result of maternal anaphylaxis to fetal antigen has much less evidence to support it. The disseminated intravascular coagulation often seen in this and other serious obstetrical illnesses may be a secondary result of complement activation rather than the direct introduction of pro-coagulants into the maternal circulation although the link between the complement and coagulation pathways, if any, remains poorly defined. Through currently available laboratory testing, both the complement hypothesis and the anaphylaxis mechanism are able to be assessed. Direct measurement of serum complement as well as serum tryptase and urinary histamine are readily obtained tests in community hospitals as well as tertiary care hospitals. If the hypothesis proves true, this investigation may be of profound importance to understanding immune tolerance. Rather, than asking why one pregnant woman in 20,000 develops a violent immune reaction to the fetus, a better question is why do not all pregnant women reject the fetus which is a large collection of foreign antigens?

Cardiopulmonary distress during obstetrical anaesthesia: attempts to diagnose amniotic fluid embolism in a case series of suspected allergic anaphylaxis

BACKGROUND

Cardiopulmonary distress during obstetrical anaesthesia may result from a drug-induced allergic reaction, but, in the obstetrical setting, allergic anaphylaxis may be inseparable from amniotic fluid embolism in terms of the clinical presentation. Further investigations, using allergy tests and other laboratory analyses, are then needed to pursue a diagnostic clarification.

METHODS

Twelve women suspected of having developed anaphylaxis during obstetrical anaesthesia underwent allergy follow-up investigations and further serological tests with the amniotic fluid embolism marker sialyl Tn and complement factors (C3 and C4) in an attempt to differentiate amniotic fluid embolism from drug-induced allergic anaphylaxis.

RESULTS

The diagnostic programme revealed one case of probable amniotic fluid embolism and four cases of probable drug-induced allergic anaphylaxis. Of the remaining seven cases, there were two cases that, by diagnostic exclusion, could be classified as possible cases of amniotic fluid embolism. The cause of the reactions remained unresolved in five cases.

CONCLUSIONS

It can be difficult to differentiate between anaphylaxis and amniotic fluid embolism, especially amongst survivors. Diagnostic markers that can be applied on peripheral blood samples are promising, but larger studies are needed to validate their use in the diagnosis of causes of cardiopulmonary distress during obstetrical anaesthesia.

Amniotic fluid embolism

INCIDENCE

Amniotic fluid embolism is a catastrophic syndrome that occurs during pregnancy or in the immediate postpartum period. Multiple case reports have described the clinical findings and have reported variable success with supportive care. There has been discrepancy with respect to the incidence and mortality of amniotic fluid embolism. One likely explanation for this inconsistency is the lack of sensitive and specific diagnostic studies to definitively identify cases of amniotic fluid embolism, leading to both over- and underreporting. Despite the variation in reported incidence and mortality, amniotic fluid embolism remains a life-threatening condition with significant morbidity and mortality for the pregnant woman. It is the fifth most common cause of maternal mortality in the world.

DIAGNOSIS

The diagnosis of amniotic fluid embolism continues to be a clinical diagnosis and a diagnosis of exclusion based on the rapid development of a complex constellation of findings with sudden cardiovascular collapse, acute left ventricular failure with pulmonary edema, disseminated intravascular coagulation, and neurologic impairment. Given the significant morbidity and mortality associated with this condition, a high index of suspicion is warranted. Suspected risk factors have included tumultuous labor, trauma, multiparity, increased gestational age, and increased maternal age. However, many patients who develop amniotic fluid embolism have no obvious risk factors.

MANAGEMENT

Patients with amniotic fluid embolus are best managed using a multidisciplinary approach. There are no pharmacologic or other therapies that prevent or treat the amniotic fluid embolism syndrome, and supportive care typically involves aggressive treatment of multiple types of shock simultaneously. In this article we discuss the clinical presentation of amniotic fluid embolism syndrome as well as current opinions regarding pathophysiology, diagnosis, and management.

Three cases of suspected hyperthermia with remarkable elevation of serum mast cell tryptase

Tryptase is a neutral protease of human mast cells, and an important indicator of mast cell activation and degranulation in anaphylactic events. The elevation of serum mast cell tryptase (SMCT) is used for postmortem diagnosis of anaphylaxis. We have quantified the SMCT levels of 122 forensic autopsy cases with various causes of death and found only three where the SMCT levels were remarkably elevated, with values of 179, 68.9 and 69.4 ng/ml (normal level <13.5 ng/ml). The three cases were suspected to have suffered from hyperthermia, and the deaths did not seem to be related to causes of death where SMCT levels have been reported to be elevated in some cases. Two cases were patients who had been prescribed long-term neuroleptics or antidepressants, and myoglobin was detected immunohistochemically in the renal tubules of both cases. The other case died of heatstroke. A possible mechanism of hyperthermia in SMCT elevation is discussed.

Usefulness of serum mast cell-specific chymase levels for postmortem diagnosis of anaphylaxis

Chymase, a serine protease, is stored mainly in secretory granules of human mast cells. Serum chymase concentration was examined in 8 autopsy cases with anaphylaxis as well as in 104 control cases without anaphylaxis. It was detected in all 8 cases with anaphylaxis (range 3-380 ng/ml, mean 89.8 ng/ml), while it was detected in only 2 of the 104 controls and was below a detectable level (<3 ng/ml) in the other 102. Serum tryptase levels are known to be a diagnostic indicator of anaphylaxis, therefore the relationship between serum chymase and tryptase levels was investigated in the 8 cases of anaphylactic death; a significant positive correlation was found (r=0.826, p=0.011). Furthermore, chymase was shown to be quite stable in serum. These results showed that measurement of serum chymase levels might be an additional tool for postmortem diagnosis of anaphylaxis.

Mast cell tryptase: a review of its physiology and clinical significance

Mast cells, which are granulocytes found in peripheral tissue, play a central role in inflammatory and immediate allergic reactions. beta-Tryptase is a neutral serine protease and is the most abundant mediator stored in mast cell granules. The release of beta-tryptase from the secretory granules is a characteristic feature of mast cell degranulation. While its biological function has not been fully clarified, mast cell beta-tryptase has an important role in inflammation and serves as a marker of mast cell activation. beta-Tryptase activates the protease activated receptor type 2. It is involved in airway homeostasis, vascular relaxation and contraction, gastrointestinal smooth muscle activity and intestinal transport, and coagulation. Serum mast cell beta-tryptase concentration is increased in anaphylaxis and in other allergic conditions. It is increased in systemic mastocytosis and other haematological conditions. Serum beta-tryptase measurements can be used to distinguish mast cell-dependent reactions from other systemic disturbances such as cardiogenic shock, which can present with similar clinical manifestations. Increased beta-tryptase levels are highly suggestive of an immunologically mediated reaction but may also occur following direct mast cell activation. Patients with increased mast cell beta-tryptase levels must be investigated for an allergic cause. However, patients without increased mast cell tryptase levels should be investigated if the clinical picture suggests severe anaphylaxis.

Serum tryptase levels in sudden infant death syndrome in forensic autopsy cases

An elevated serum tryptase concentration is considered to be a specific marker for systemic mast-cell activation, a central feature of anaphylaxis, which has been observed in some cases of sudden infant death syndrome (SIDS). However, it is still unclear whether anaphylaxis is involved in the etiology for SIDS. In the present study, we measured serum tryptase levels in 21 infants with SIDS, and 14 control infants from forensic autopsy cases by Uni-CAP TRYPTASE Fluoroenzyme immunoassay system, which detects both alpha- and beta-tryptase. The assay did not show any significant elevation of tryptase levels in the SIDS group compared with controls. Additionally, increased concentrations of tryptase were not observed in any SIDS case. Our results indicated that anaphylaxis does not seem to be involved in the etiology of SIDS.

Amniotic fluid embolism with involvement of the brain, lungs, adrenal glands, and heart

The case of a healthy 31-year-old woman in the 40th week of second pregnancy is presented. During preparation for an emergency caesarean section, she developed an amniotic fluid embolism (AFE) with unusual and unique features. The acute onset of disease with cardiorespiratory failure with hypotension, tachycardia, cyanosis, respiratory disturbances and loss of consciousness, suggested at first a pulmonary thromboembolism, but the appearance of convulsions led to the diagnosis of AFE. 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. Eosinophilic inflammatory infiltrates were found in the lungs, hepatic portal fields and especially in the heart, suggesting a specific hypersensitivity reaction to fetal antigens. Moreover, intravascular accumulation of macrophages in the lungs also favored a non-specific immune reaction to amniotic fluid constituents.

Amniotic fluid embolus: can we affect the outcome?

PURPOSE OF REVIEW

Amniotic fluid embolism is a rare catastrophe unique to pregnancy. Its mortality rate remains high despite efforts at prompt and aggressive management protocols, highlighting the need to maintain a high index of suspicion.

RECENT FINDINGS

The intrusion of amniotic fluid into the maternal bloodstream may lead in certain women to a complex series of physiological reactions mimicking those seen in human anaphylaxis or sepsis, negating the purely embolic phenomenon theory as previously understood. The clinical picture is the sudden onset of cardiovascular collapse, cyanosis, haemorrhage or disseminated intravascular coagulopathy, during or soon after delivery.

SUMMARY

The mainstay of a successful outcome remains the identification of high-risk patients, as well as early clinical diagnosis and management.

Amniotic fluid embolism

PURPOSE OF REVIEW

To review the recent literature on amniotic fluid embolism and how it may influence the clinical management and further study of the condition. Morbidity and mortality from amniotic fluid embolism in the international context will be described, given the recent Confidential Enquiries into Maternal Deaths in the United Kingdom and other studies. With this rare condition we need to look for clues as to how to facilitate diagnosis and improve outcomes.

RECENT FINDINGS

Amniotic fluid embolism continues to be a leading cause of maternal death. There has been a decrease in mortality from amniotic fluid embolism in the UK from 5.1 to 3.7 per million maternities, but it is still the fifth greatest cause of direct maternal death. In France, 13% of deaths are caused by amniotic fluid embolism, the third highest cause. In Singapore, a study of postmortems found that over 30% of direct maternal deaths were caused by amniotic fluid embolism, the most common cause. Case-specific mortality may not be as high as previously thought. The early data from the UK Register of cases show only 16% mortality, although there is significant maternal and neonatal morbidity. Early diagnosis may be the best way to improve outcomes. Case reports suggest that plasma exchange techniques may be helpful after initial resuscitation.

SUMMARY

With a rare condition additions to the literature are sparse. Early consideration of the diagnosis after prompt resuscitation is needed. Further data are needed to advance beyond this.