Forensic aspects of post-mortem histological detection of amniotic fluid embolism

Technical note: double immunohistochemical stain (anti-CD31 and anti-cytokeratins) as a tool for a confident forensic post-mortem diagnosis of amniotic fluid embolism

Amniotic fluid embolism (AFE) is a rare cause of unexpected late maternal gestational death. The forensic post-mortem diagnosis is rendered upon the histological recognition of fetal "foreign" material inside maternal lung vasculature. The authors propose a double immunohistochemical (anti-CD31 plus anti-cytokeratin AE1/AE3) stain in order to assess accurate amniotic fluid pulmonary embolic burden in a highly reproducible fashion based on the fact that such technique allows to detect an impressive amount of scales within lung vasculature, thereby offering further evidence that pulmonary embolic obstructive microangiopathy, rather than anaphylactoid reaction, is major determinant in AFE-related death.

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

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

Intraluminal Arterial Filling Defects Misdiagnosed as Pulmonary Emboli: What Else Could They Be?

Pulmonary artery filling defects can be observed in various pathologic processes other than pulmonary embolism, for example, nonthrombotic pulmonary embolism with biological and nonbiological materials and intrinsic pulmonary artery lesions. They have also been described in rare conditions, such as fibrosing mediastinitis and congenital absence or stenosis of pulmonary artery, and some pulmonary parenchymal and airway malignancies. Misdiagnosis is common owing to the relative rarity of these conditions. Correct diagnosis is based on the appropriate clinical suspicion considering the unique clinical features, laboratory findings, and additional radiologic clues inferring a pathology other than pulmonary embolism.

Translational Research in Pediatrics IV: Solid Tissue Collection and Processing

Solid tissues are critical for child-health research. Specimens are commonly obtained at the time of biopsy/surgery or postmortem. Research tissues can also be obtained at the time of organ retrieval for donation or from tissue that would otherwise have been discarded. Navigating the ethics of solid tissue collection from children is challenging, and optimal handling practices are imperative to maximize tissue quality. Fresh biopsy/surgical specimens can be affected by a variety of factors, including age, gender, BMI, relative humidity, freeze/thaw steps, and tissue fixation solutions. Postmortem tissues are also vulnerable to agonal factors, body storage temperature, and postmortem intervals. Nonoptimal tissue handling practices result in nucleotide degradation, decreased protein stability, artificial posttranslational protein modifications, and altered lipid concentrations. Tissue pH and tryptophan levels are 2 methods to judge the quality of solid tissue collected for research purposes; however, the RNA integrity number, together with analyses of housekeeping genes, is the new standard. A comprehensive clinical data set accompanying all tissue samples is imperative. In this review, we examined: the ethical standards relating to solid tissue procurement from children; potential sources of solid tissues; optimal practices for solid tissue processing, handling, and storage; and reliable markers of solid tissue quality.

The role of histopathology in forensic practice: an overview

The role of forensic histopathology in routine practice is to establish the cause of death in particular cases. This is achieved on the basis of microscopic analysis of representative cell and tissue samples taken from the major internal organs and from abnormal findings made at autopsy. A prerequisite of this is adherence to the quality standards set out for conventional histological/cytological staining and enzyme histochemical and immunohistochemical methods. The interpretation of histological findings is performed by taking into account macroscopic autopsy findings and information on previous history. Histological analysis may prompt postmortem biochemical and chemical-toxicological investigations. The results of histological analysis need to be classified by experts in the context of the available information and the need to withstand the scrutiny of other experts.

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.

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: 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.

An autopsy report on a ruptured rudimentary horn (uterine anomaly) with ectopic pregnancy

The rudimentary horn is a rare developmental anomaly of the Müllerian duct. Ectopic pregnancy in the rudimentary horn is estimated to occur in one out of 76,000-150,000 pregnancies. A 30-year-old primigravida suddenly collapsed after 3 days of continuous abdominal pain. Emergency laparotomy revealed a massive intraperitoneal hemorrhage and fetal demise. The growth of the fetus after 19 weeks of gestation is believed to have caused the rudimentary horn rupture, thereby rapidly leading to hemorrhagic shock in the mother and ischemic death in the fetus. This is the first autopsy report on maternal death due to the rudimentary horn or other Müllerian duct anomalies, which emphasizes the need for forensic pathologists to consider this condition as a possible cause of unexpected death in fertile women. In addition, it is very important for clinicians to detect Müllerian duct anomalies by sonography during routine obstetric examinations, and promptly diagnose anomaly related ectopic pregnancies in women displaying symptoms of an acute abdomen, intraperitoneal hemorrhage, or shock in the emergency practice.

Maternal and pregnancy-related death: causes and frequencies in an autopsy study population

BACKGROUND

Maternal deaths during pregnancy, both from pregnancy-related or other causes, are rare in Western industrialized countries. In this study we report maternal and pregnancy-related deaths in a large autopsy population focusing on medical history, autopsy findings and histological examinations.

MATERIALS AND METHODS

Medico-legal autopsy files (n = 11,270) from the Institute of Legal Medicine and Forensic Sciences, University Medical Centre Charité, University of Berlin, and the State Institute of Legal and Social Medicine, Berlin, from 2005 to 2010 were reviewed. All female cases between 15 and 49 years were checked for maternal and pregnancy-related death, and deaths of pregnant women from non-natural causes were also included. Fatalities that met the chosen criteria were classified as "direct gestational death," "indirect gestational death" or "non-gestational death."

RESULTS

13 female fatalities (0.12 %) met the chosen criteria (median age 28 years ± 6.87 SD). Eight (61.5 %) women died in-hospital, four (30.8 %) at home, and one woman died in public. Three cases (23.1 %) were "non-gestational deaths," and one case (7.7 %) remained unclear after autopsy and additional examinations. Of the remaining nine cases, six cases (46.5 %) were "direct gestational deaths," and two cases (15.4 %) were "indirect gestational deaths." One case (7.7 %) was not to be defined as "late maternal death," but the cause of death seemed to be directly related to previous gestation ["(very) late maternal death"].

CONCLUSION

Maternal deaths during pregnancy, both from pregnancy-related or other causes, remain an uncommon event in routine forensic autopsy practice. We report on the collection and analysis of maternal and pregnancy-related deaths in a large autopsy population, with particular attention to the phenomenology of pregnancy, pathophysiological changes in different organ systems and their detection, and the forensic autopsy assessment.

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?

Amniotic fluid embolism-apropos two consecutive cases

Amniotic fluid embolism (AFE) is a sporadic, unpredictable, and usual fatal obstetric complication. The paper deals with two cases of maternal deaths because of AFE verified by medicolegal autopsy. In both the cases, several known risk factors associated with AFE, such as increased maternal age (41 and 35 years), diabetes, augmented labor, and cesarean delivery, were identified. Clinical features were typical, including sudden onset of cardiovascular and respiratory symptoms. In the patient who survived longer, both clinical and autopsy signs of disseminated intravascular coagulopathy were present, while they were absent in the case where death occurred rapidly. This paper describes briefly the particular features to look for at autopsy and stresses the importance of histology examination and staining techniques.

Amniotic fluid aspiration in cases of SIDS

The scope of this study was to evaluate the incidence and the eventual consequences of amniotic fluid aspiration (AFA) in cases of sudden infant death. Cases of sudden infant death syndrome (SIDS; n = 113: 39 females, 74 males; mean age 4.6 months) were compared to a control group of 39 cases of explained death (14 females, 25 males; mean age 5.6 months). In each case, sections of the lung stained with hematoxylin and eosin and with the immunohistochemical reaction 34BE12 specific for cytokeratins were available. The microscope slides were observed at x200 magnification and semi-quantitatively classified into four categories(-, +, ++, and +++). In both groups, rests of amniotic fluid could be observed up to the fourth month of life. The comparison between the two groups did not show any significant difference. In the SIDS group, immunohistochemical reactions with the antibodies CD68, MRP8, MRP14, 27E10, 25F9, CD3, CD20Cy, and CD45R0 were available for the lungs. Twelve cases with AFA were compared to a group of SIDS cases without AFA with similar age and pathological distribution to evaluate whether the presence of amniotic remnants induced inflammatory changes in the lungs. No differences emerged. This study shows that AFA is not a rare event. Even moderate to severe AFA does not necessary cause death. A correlation between AFA and SIDS could not be shown.

Immunohistochemical identification of prevalent right ventricular ischemia causing right heart failure in cases of pulmonary fat embolism

Pulmonary fat embolism is a life-threatening event that may result to potentially determining right ventricular failure. Even if the pathophysiology of this phenomenon has been widely investigated, no immunohistochemical demonstration of right ventricular failure following pulmonary fat embolism has been reported till now. We performed an immunohistochemical investigation with the markers fibronectin and C5b-9 in 21 cases of polytrauma with bone fractures (study group-nine females and 12 males; mean age 64.6 years) compared to a control group of 21 forensic cases with various causes of death (nine females and 12 males; mean age 68.6 years). In each case at least one tissue slide from both cardiac ventricles (free wall of the right ventricle, anterior and/or posterior wall of the left ventricle) was available. The reactions were semi-quantitatively classified, and the two groups were compared. In the study group, the occurrence of ischemic changes at the right ventricle was significantly higher than in controls. The determining aspect, however, seems to be the prevalent ischemic lesion at the right ventricle compared to the left one. This may indicate the primary involvement of the right ventricle, thus, demonstrating a right ventricular failure.