Squamous cells in the maternal pulmonary circulation

Current concepts in the use of cell salvage in obstetrics

PURPOSE OF REVIEW

The worldwide leading cause of maternal death is severe maternal hemorrhage. Maternal hemorrhage can be profound leading to an entire loss of blood volume. In the past two decades, Patient Blood Management has evolved to improve patient's care and safety. In surgeries with increased blood loss exceeding 500 ml, the use of cell salvage is strongly recommended in order to preserve the patient's own blood volume and to minimize the need for allogeneic red blood cell (RBC) transfusion. In this review, recent evidence and controversies of the use of cell salvage in obstetrics are discussed.

RECENT FINDINGS

Numerous medical societies as well as national and international guidelines recommend the use of cell salvage during maternal hemorrhage.

SUMMARY

Intraoperative cell salvage is a strategy to maintain the patient's own blood volume and decrease the need for allogeneic RBC transfusion. Historically, cell salvage has been avoided in the obstetric population due to concerns of iatrogenic amniotic fluid embolism (AFE) or induction of maternal alloimmunization. However, no definite case of AFE has been reported so far. Cell salvage is strongly recommended and cost-effective in patients with predictably high rates of blood loss and RBC transfusion, such as women with placenta accreta spectrum disorder. However, in order to ensure sufficient practical experience in a multiprofessional obstetric setting, liberal use of cell salvage appears advisable.

The Anaphylactoid Syndrome of Pregnancy: Two Autopsy Cases

The anaphylactoid syndrome of pregnancy (ASP) is a rare emergency with significant mortality and morbidity, in which the amniotic fluid and fetal cells enter the maternal circulation leading to respiratory failure, altered mental status, hypotension, and disseminated intravascular coagulation. The term ASP was recently introduced to replace the term amniotic fluid embolism since the clinical manifestations of the entity were more similar to a septic or anaphylactic shock rather than that of an embolic event. Two autopsy cases are described, regarding a 35-year-old gravida 2 para 1 and a 34-year-old gravida 1 para 0, where the cause of death was determined to be ASP.

Lung iodine mapping images of acute postpartum dyspnea without pulmonary thromboembolism using dual-energy CT

BACKGROUND

Postpartum dyspnea is commonly observed, but its cause is often unknown.

PURPOSE

To investigate postpartum dyspnea, we compared lung iodine mapping (LIM) using dual-energy computed tomography (DECT) between postpartum women and women suspected of having pulmonary thromboembolism (PTE).

MATERIAL AND METHODS

In this retrospective study, 109 women of reproductive age (50 postpartum women, 59 women unrelated to pregnancy) underwent DECT between March 2009 and August 2020. Among the postpartum women, 23 patients were excluded due to late-onset dyspnea (n=20: >48 h after delivery) or the presence of PTE (n=3). A total of 86 patients were divided into three groups (27 postpartum women [postpartum group], 19 women with PTE [PTE group], and 40 women without PTE [non-PTE group]). Quantitation was applied to a decreased LIM value (LIM5; defined as <5 HU) and the relative value of LIM5 to whole LIM volume (%LIM5). LIM defects were classified into five patterns (0 = none, 1 = wedge-shaped, 2 = reticular/liner, 3 = diffuse granular/patchy, 4 = massive defects) based on a consensus between two readers.

RESULTS

There were significant differences in the LIM5 and %LIM5 values among the three groups. The LIM5 and %LIM5 were largest in the PTE group, and postpartum women showed intermediate values between the non-PTE and PTE groups. Wedge-shaped defects were prominent in the PTE group, and diffuse granular/patchy defect was a typical feature in the postpartum group.

CONCLUSION

Postpartum women with dyspnea showed granular/patchy defects on DECT with a median quantitative value between the PTE and non-PTE groups.

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 rescued by venoarterial extracorporeal membrane oxygenation

Background

Amniotic fluid embolism (AFE) is a rare but often catastrophic complication of pregnancy that leads to cardiopulmonary dysfunction and severe disseminated intravascular coagulopathy (DIC). Although few case reports have reported successful use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) with AFE, concerns can be raised about the increased bleeding risks with that device.

Methods

This study included patients with AFE rescued by VA-ECMO hospitalized in two high ECMO volume centers between August 2008 and February 2021. Clinical characteristics, critical care management, in-intensive care unit (ICU) complications, and hospital outcomes were collected. ICU survivors were assessed for health-related quality of life (HRQL) in May 2021.

Results

During that 13-year study period, VA-ECMO was initiated in 54 parturient women in two high ECMO volume centers. Among that population, 10 patients with AFE [median (range) age 33 (24–40), SAPS II at 69 (56–81)] who fulfilled our diagnosis criteria were treated with VA-ECMO. Pregnancy evolved for 36 (30–41) weeks. Seven patients had a cardiac arrest before ECMO and two were cannulated under cardiopulmonary resuscitation. Pre-ECMO hemodynamic was severely impaired with an inotrope score at 370 (55–1530) μg/kg/min, a severe left ventricular ejection fraction measured at 14 (0–40)%, and lactate at 12 (2–30) mmol/L. 70% of these patients were alive at hospital discharge despite an extreme pre-ECMO severity and massive blood product transfusion. However, HRQL was lower than age-matched controls and still profoundly impaired in the role-physical, bodily pain, and general health components after a median of 44 months follow-up.

Conclusion

In this rare per-delivery complication, our results support the use of VA-ECMO despite intense DIC and ongoing bleeding. Future studies should focus on customized, patient-centered, rehabilitation programs that could lead to improved HRQL in this population.

Biochemical effects of intraoperative cell salvage and autotransfusion during cesarean section: A prospective pilot study

AIM

Intraoperative cell salvage and autotransfusion (ICSA) is a useful technique for women undergoing cesarean sections who are predicted to experience significant bleeding. This method can reduce allogeneic transfusions as well as its associated risks and costs. Amniotic fluid embolism (AFE) is an abnormal maternal response to ICSA similar to the classic systemic inflammatory response syndrome, but its mechanism is not well understood. This study was conducted to investigate the biochemical aspects of AFE.

METHODS

A prospective case-controlled pilot study was conducted in a general perinatal hospital in Japan. ICSA was performed using a two-step retransfusion process. Blood samples were collected presurgery, immediately postsurgery, and 24 h after surgery. Changes in sialyl Tn antigen (STN), complement C3 and C4, fibrinogen, and fibrin degradation product and D-dimer, C1 esterase inhibitor, and interleukin-8 (all considered AFE-related markers) activities were compared between patients who underwent cesarean sections with ICSA (ICSA group) versus without ICSA (control group).

RESULTS

Fibrinogen levels were significantly lower in the ICSA group than in the control group before surgery but not immediately after or 24 h after surgery. D-dimer was significantly higher immediately after surgery but not 24 h later. STN was significantly lower only before surgery. None of the AFE-related markers showed significant differences between the groups after 24 h. No adverse events were observed in the ICSA group.

CONCLUSIONS

There is no clinical evidence that ICSA alters the biochemical statuses of AFE-related markers in a manner that could lead to adverse maternal responses.

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.

A randomised controlled trial and economic evaluation of intraoperative cell salvage during caesarean section in women at risk of haemorrhage: the SALVO (cell SALVage in Obstetrics) trial

BACKGROUND

Caesarean section is associated with blood loss and maternal morbidity. Excessive blood loss requires transfusion of donor (allogeneic) blood, which is a finite resource. Cell salvage returns blood lost during surgery to the mother. It may avoid the need for donor blood transfusion, but reliable evidence of its effects is lacking.

OBJECTIVES

To determine if routine use of cell salvage during caesarean section in mothers at risk of haemorrhage reduces the rates of blood transfusion and postpartum maternal morbidity, and is cost-effective, in comparison with standard practice without routine salvage use.

DESIGN

Individually randomised controlled, multicentre trial with cost-effectiveness analysis. Treatment was not blinded.

SETTING

A total of 26 UK obstetric units.

PARTICIPANTS

Out of 3054 women recruited between June 2013 and April 2016, we randomly assigned 3028 women at risk of haemorrhage to cell salvage or routine care. Randomisation was stratified using random permuted blocks of variable sizes. Of these, 1672 had emergency and 1356 had elective caesareans. We excluded women for whom cell salvage or donor blood transfusion was contraindicated.

INTERVENTIONS

Cell salvage (intervention) versus routine care without salvage (control). In the intervention group, salvage was set up in 95.6% of the women and, of these, 50.8% had salvaged blood returned. In the control group, 3.9% had salvage deployed.

MAIN OUTCOME MEASURES

Primary - donor blood transfusion. Secondary - units of donor blood transfused, time to mobilisation, length of hospitalisation, mean fall in haemoglobin, fetomaternal haemorrhage (FMH) measured by Kleihauer-Betke test, and maternal fatigue. Analyses were adjusted for stratification factors and other factors that were believed to be prognostic a priori. Cost-effectiveness outcomes - costs of resources and service provision taking the UK NHS perspective.

RESULTS

We analysed 1498 and 1492 participants in the intervention and control groups, respectively. Overall, the transfusion rate was 2.5% in the intervention group and 3.5% in the control group [adjusted odds ratio (OR) 0.65, 95% confidence interval (CI) 0.42 to 1.01; p = 0.056]. In a planned subgroup analysis, the transfusion rate was 3.0% in the intervention group and 4.6% in the control group among emergency caesareans (adjusted OR 0.58, 95% CI 0.34 to 0.99), whereas it was 1.8% in the intervention group and 2.2% in the control group among elective caesareans (adjusted OR 0.83, 95% CI 0.38 to 1.83) (interaction p = 0.46, suggesting that the difference in effect between subgroups was not statistically significant). Secondary outcomes did not differ between groups, except for FMH, which was higher under salvage in rhesus D (RhD)-negative women with RhD-positive babies (25.6% vs. 10.5%, adjusted OR 5.63, 95% CI 1.43 to 22.14; p = 0.013). No case of amniotic fluid embolism was observed. The additional cost of routine cell salvage during caesarean was estimated, on average, at £8110 per donor blood transfusion avoided.

CONCLUSIONS

The modest evidence for an effect of routine use of cell salvage during caesarean section on rates of donor blood transfusion was associated with increased FMH, which emphasises the need for adherence to guidance on anti-D prophylaxis. We are unable to comment on long-term antibody sensitisation effects. Based on the findings of this trial, cell salvage is unlikely to be considered cost-effective.

FUTURE WORK

Research into risk of alloimmunisation among women exposed to cell salvage is needed.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN66118656.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 2. See the NIHR Journals Library website for further project information.

How about "The effect of intraoperative cell salvage on allogeneic blood transfusion for patients with placenta accreta"?: An observational study

Intraoperative cell salvage (IOCS) for high-risk obstetric hemorrhage is now endorsed by a number of obstetric organizations. Most previous studies have focused on the safety of IOCS from case series and small controlled studies. Here, we describe the effect of IOCS on rates of allogeneic blood transfusion (ABT) under different degrees of bleeding during cesarean section in women with placenta accreta, which has seldom been reported in the literature.We conducted a retrospective analysis on the introduction of routine application of IOCS for the management of hemorrhage during cesarean section in women with placenta accreta. We identified 115 women, with prenatally diagnosed placenta accreta/increta/percreta before this change in practice, who served as controls, and 108 women who had IOCS applied during cesarean section.Compared with the control treatment, IOCS was significantly associated with a lower incidence of ABT (odds ratio, 0.179; 95% confidence interval, 0.098-0.328). Among the women with ≤3000 mL of bleeding, ABT was avoided in 80 (93.0%) of the 86 patients in the IOCS group, while 49 (50.0%) of the 98 controls required ABT. For women with an estimated blood loss >3000 mL, the reinfused IOCS blood may have helped prevent the need for ABT in 6 (28.6%) of the 21 patients, while all of the 17 controls required ABT. Subgroup analysis of coagulation function and the need for coagulation components showed no significant difference between the 2 groups (P > .05). Compared with the control treatment, IOCS was associated with a lower intraoperative volume of crystalloid (P < .01) and colloid infusion (P < .01) and a shorter length of postoperative hospital stay (P < .01) in patients with placenta accreta. In addition, there were no complications or adverse reactions in patients with placenta accreta who underwent IOCS.IOCS helped reduce the need for ABT and fluid transfusion in patients with placenta accreta and may be safe for use in obstetrics.

Squamous cell carcinoma antigen as a novel candidate marker for amniotic fluid embolism

AIM

We aimed to evaluate the clinical usefulness of serum squamous cell carcinoma (SCC) antigen for the diagnosis of amniotic fluid embolism (AFE).

METHODS

Sera and information of 20 patients with AFE (autopsy-proven AFE, four cases; clinical AFE, 16 cases) were obtained from the Japan Amniotic Fluid Embolism Registration Center at Hamamatsu University School of Medicine. As controls, we included 74 gestational-age-matched healthy women who gave birth to healthy newborns during the period from December 2012 to January 2014. Receiver-operator curves (ROC) were used to evaluate the diagnostic performance of SCC levels for prediction of AFE.

RESULTS

Serum SCC antigen levels in women with autopsy-proven AFE (112.0 ± 169.4 ng/mL, P = 0.001) and clinical AFE (9.5 ± 10.3 ng/mL, P = 0.004) were significantly higher than those in healthy controls with normal delivery (4.4 ± 2.2 ng/mL). On ROC analysis, the optimal cut-off value for SCC antigen levels was 7.15 ng/mL, for which the sensitivity and specificity for AFE prediction was 60.0% and 89.2%, respectively (area under the ROC, 0.785; 95% confidence interval, 0.663-0.908; P < 0.001).

CONCLUSION

Serum SCC antigen may be a promising predictor of the entry of amniotic fluid into the maternal circulation, potentially serving as a candidate marker for noninvasive diagnosis of AFE.

Defining definitions: a Delphi study to develop a core outcome set for conditions of severe maternal morbidity

OBJECTIVE

Develop a core outcome set of international consensus definitions for severe maternal morbidities.

DESIGN

Electronic Delphi study.

SETTING

International.

POPULATION

Eight expert panels.

METHODS

All 13 high-income countries represented in the International Network of Obstetric Surveillance Systems (INOSS) nominated five experts per condition of morbidity, who submitted possible definitions. From these suggestions, a steering committee distilled critical components: eclampsia: 23, amniotic fluid embolism: 15, pregnancy-related hysterectomy: 11, severe primary postpartum haemorrhage: 19, uterine rupture: 20, abnormally invasive placentation: 12, spontaneous haemoperitoneum in pregnancy: 16, and cardiac arrest in pregnancy: 10. These components were assessed by the expert panel using a 5-point Likert scale, following which a framework for an encompassing definition was constructed. Possible definitions were evaluated in rounds until a rate of agreement of more than 70% was reached. Expert commentaries were used in each round to improve definitions.

MAIN OUTCOME MEASURES

Definitions with a rate of agreement of more than 70%.

RESULTS

The invitation to participate in one or more of eight Delphi processes was accepted by 103 experts from 13 high-income countries. Consensus definitions were developed for all of the conditions.

CONCLUSION

Consensus definitions for eight morbidity conditions were successfully developed using the Delphi process. These should be used in national registrations and international studies, and should be taken up by the Core Outcomes in Women's and Newborn Health initiative.

TWEETABLE ABSTRACT

Consensus definitions for eight morbidity conditions were successfully developed using the Delphi process.

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.

Autologous and Nonautologous Blood Transfusion in Patients with Ruptured Ectopic Pregnancy and Severe Blood Loss

BACKGROUND

There are some theoretical concerns for the use of intraoperative cell salvage (ICS) in patients with ectopic pregnancy. This study aimed to observe the impact of ICS on the coagulation function and clinical outcomes of patients with ruptured ectopic pregnancy and severe blood loss.

METHODS

This was a retrospective study of 225 patients with ruptured ectopic pregnancy and severe blood loss treated at the Third Affiliated Hospital of Guangxi Medical University between January 2012 and May 2016. Patients were grouped according to ICS (n = 116) and controls (n = 109, allogenic transfusion and no transfusion).

RESULTS

Compared with controls, patients with ICS had shorter hospitalization (P = 0.007), lower requirement for allogenic blood products (P < 0.001), and higher hemoglobin levels at discharge (P < 0.001). There were no complications/ adverse reactions. In the ICS group, hemoglobin at discharge (-6.5%, P = 0.002) and thrombin time (-3.7%, P = 0.002) were decreased 24 h after surgery, while 24 h APTT was increased (+4.6%, P < 0.001). In the control group, hemoglobin at discharge (-16.8%, P < 0.001) was decreased after surgery and 24 h APTT was increased (+2.4%, P = 0.045). At discharge, hemoglobin levels were higher in the ICS group (P < 0.001).

CONCLUSION

ICS was associated with good clinical outcomes in patients with ruptured ectopic pregnancy and severe blood loss.

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.

An example of prompt and appropriate multidisciplinary management leading to an exceptionally good outcome: a case complicated by amniotic fluid embolism

Amniotic fluid embolism (AFE) is a rare and serious phenomenon; we describe a rare case of AFE occurring after a second trimester surgical termination in a private clinic, which, with prompt transfer and appropriate multidisciplinary management, had an exceptionally good outcome. The patient developed hypotension, respiratory arrest and disseminated intravascular coagulopathy following the procedure but with aggressive management she made a full recovery without any neurological or long-term sequelae.

Acute respiratory failure in pregnancy

Respiratory failure affects up to 0.2% of pregnancies, more commonly in the postpartum period. Altered maternal respiratory physiology affects the assessment and management of these patients. Respiratory failure may result from pregnancy-specific conditions such as preeclampsia, amniotic fluid embolism or peripartum cardiomyopathy. Pregnancy may increase the risk or severity of other conditions, including thromboembolism, asthma, viral pneumonitis, and gastric acid aspiration. Management during pregnancy is similar to the nonpregnant patient. Endotracheal intubation in pregnancy carries an increased risk, due to airway edema and rapid oxygen desaturation following apnea. Few data are available to direct prolonged mechanical ventilation in pregnancy. Chest wall compliance is reduced, perhaps permitting slightly higher airway pressures. Optimizing oxygenation is important, but data on the use of permissive hypercapnia are limited. Delivery of the fetus does not always improve maternal respiratory function, but should be considered if benefit to the fetus is anticipated.

Implementation of an obstetric cell salvage service in a tertiary women's hospital

INTRODUCTION

Intraoperative cell salvage (ICS) is an important aspect of patient blood management programmes. An ICS service was introduced at KK Women's and Children's Hospital, Singapore, from 2 May 2011 to 30 April 2013 to aid in the management of massive obstetric haemorrhage.

METHODS

With support from the Ministry of Health's Healthcare Quality Improvement and Innovation Fund, a workgroup comprising obstetricians, anaesthetists and nursing staff was formed to develop training requirements, clinical guidelines and protocols for implementing ICS using the Haemonetics Cell Saver 5. Pregnant women with an anticipated blood loss of > 1,000 mL during Caesarean delivery, a baseline haemoglobin level of < 10 g/dL, rare blood types and who had refused donor blood were recruited to the service after obtaining informed consent.

RESULTS

A total of 11 women were recruited to the ICS service; the primary indications were placenta praevia and placenta accreta. Median blood loss in these 11 patients was 1,500 (range 400-3,000) mL. In four patients, adequate autologous blood was collected to initiate processing and salvaged, processed blood was successfully reinfused (mean 381.3 [range 223.0-700.0] mL). Median blood loss among these four patients was 2,000 (range 2,000-3,000) mL. No adverse event occurred following autologous transfusion. Mean immediate postoperative haemoglobin level was 8.0 (range 7.1-9.4) g/dL.

CONCLUSION

The implementation of an obstetric ICS service in our institution was successful. Future studies should seek to address the cost-effectiveness of ICS in reducing allogeneic blood utilisation.

From appearance to essence: 10 years review of atypical amniotic fluid embolism

PURPOSE

Amniotic fluid embolism (AFE) is an unpredictable and unpreventable complication of maternity. The presentation may range from relatively subtle clinical events to sudden maternal cardiac arrest. However, the neglected diagnosis of non-classical form of AFE (atypical AFE) is very common. The aim of this study was to examine population-based regional data from Suzhou, China. Based on the analysis of all available case reports, we put forward an outline of atypical AFE and investigate whether any variation identified could be ascribed to methodology.

METHODS

Retrospective study from January 2004 to December 2013, 53 cases was identified from the database of Center for Disease Control (CDC) in the city of Suzhou. We investigated the presentations of atypical AFE and maternal characteristics with potential factors underlying AFE. Multiple-regression analysis was used to calculate adjusted odds ratios (ORs) and 95 % confidence intervals (CIs).

RESULTS

The incidence of AFE was 6.91 per 100,000 deliveries (53/766,895). Seventeen deaths occurred, a mortality rate of 32 %. Atypical AFE may as the earlier stage or mild form of AFE, there was no death case in the study with timely remedy. The atypical AFE appear is obstetric hemorrhage and/or pulmonary and renal dysfunction postpartum. Hyperfibrinolysis and coagulopathy may the early laboratory findings of atypical AFE. Atypical and classical AFE shared the same risks, such as advanced maternal age, placental abnormalities, operative deliveries, eclampsia, cervical lacerations, and induction of labor.

CONCLUSION

Staying alert to premonitory symptoms of AFE is critical to turn it to a remediable disease. Patient complaints such as breathlessness, chest pain, feeling cold, distress, panic, a feeling of nausea, and vomiting should elicit close attention. The management of a suspected episode of amniotic fluid embolism is generally considered to be supportive. Hysterectomy must be performed if there is further progression of symptoms. Due to advances in acute care, mortality has decreased in recent years, highlighting the importance of early detection and treatment.

Acute postpartum pulmonary edema in a 23-year-old woman 5 days after cesarean delivery

The presentation of acute dyspnea after pregnancy is rare, but should bring a number of important conditions to the mind of the attending physician. Pulmonary embolism, amniotic fluid embolism, pneumonia, aspiration and pulmonary edema are some of the potentially devastating causes that must be considered. The percentage of pregnancies that are complicated by acute pulmonary edema has been estimated to be 0.08%. The most common contributing factors include the administration of tocolytic agents, underlying cardiac disease, iatrogenic fluid overload and preeclampsia. No matter what the underlying pathology, prompt administration of appropriate resuscitation is always the first priority. Only after the patient has been stabilized can attention be turned to diagnosis and specific treatment. This case examines one such presentation and reviews some of the diagnostic possibilities.

Investigation of Pregnancy-Related Deaths

The maternal mortality ratio (MMR), the number of maternal deaths per 100 000 live births, has become a central indicator of public health as well as a means to compare healthcare amongst various states and countries. In addition, it is used to indicate cultural variables including socioeconomic, sexual, and racial inequality of health care access amongst many systems. Thus, the accurate investigation and reporting of all maternal deaths is paramount to public health advancement. Issues central to the maternal mortality ratio include those risk factors increasing exponentially in society as a whole, such as increased maternal age and obesity, as well as those risk factors central to specific societies and cultures, such as illegal abortion and rights to contraception. In the United States, the maternal mortality ratio has increased rather than decreased over the past two decades, leading to concern and consternation amongst public officials, healthcare providers, and the public. This population of women under 50 is generally not expected to succumb to complications of pregnancy and thus investigation and reporting in each case is vital to advancement in this field. Herein, we will review several causes of maternal death and consider strategies and techniques to reach the most probable conclusions regarding the cause and manner of death.

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.

Pulmonary Embolic Disorders

Deaths due to pulmonary thromboemboli are frequently encountered by the forensic pathologist and account for a significant percentage of sudden, unexpected deaths. Diagnosing these straightforward cases is often not a challenge, but unfortunately some cases in which a thromboembolism is expected can become complicated. Occasionally, a postmortem clot may mimic a thromboembolism and lead to a mistaken diagnosis, and in other situations it may become paramount to attempt to age a thrombus as part of a medicolegal lawsuit. Additionally, many individuals use the less specific term, “pulmonary emboli”, when referring to these cases in which a portion of a thrombus, usually originating in the deep veins of the lower extremities, breaks off and travels to the pulmonary vasculature bed where it occludes vessels and leads to a rapid demise. One must remember, though, that several other materials and tissues including fat, amniotic fluid, air, tumors, solid organs, synthetic materials, and parasites may be displaced and embolize to the lungs and cause significant disease. In the following pages we will provide a thorough review of pulmonary embolic disorders, focusing on those diseases most likely to be encountered by the forensic pathologist. The aim of this review is to aid the pathologist in using proper terminology, diagnosing various types of embolic disorders, and recognizing potential mimics.

Acute hypotension associated with intraoperative cell salvage using a leukocyte depletion filter during management of obstetric hemorrhage due to amniotic fluid embolism

Amniotic fluid embolism (AFE) is a rare but catastrophic obstetric complication that can lead to profound coagulopathy and hemorrhage. The role of cell salvage and recombinant human Factor VIIa (rFVIIa) administration in such cases remains unclear. We present a case of AFE and describe our experience with the use of cell salvage and rFVIIa administration during the resuscitation. Cell salvage and transfusion through a leukocyte depletion filter was attempted after the diagnosis of AFE was made, but the attempted transfusion was immediately followed by hypotension and a worsening of hemodynamics. rFVIIa, on the contrary, was used with clinical improvement in coagulopathy and without apparent adverse thrombotic effect.

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-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 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.

Cell salvage as part of a blood conservation strategy in anaesthesia

The use of intraoperative cell salvage and autologous blood transfusion has become an important method of blood conservation. The main aim of autologous transfusion is to reduce the need for allogeneic blood transfusion and its associated complications. Allogeneic blood transfusion has been associated with increased risk of tumour recurrence, postoperative infection, acute lung injury, perioperative myocardial infarction, postoperative low-output cardiac failure, and increased mortality. We have reviewed the current evidence for cell salvage in modern surgical practice and examined the controversial issues, such as the use of cell salvage in obstetrics, and in patients with malignancy, or intra-abdominal or systemic sepsis. Cell salvage has been demonstrated to be safe and effective at reducing allogeneic blood transfusion requirements in adult elective surgery, with stronger evidence in cardiac and orthopaedic surgery. Prolonged use of cell salvage with large-volume autotransfusion may be associated with dilution of clotting factors and thrombocytopenia, and regular laboratory or near-patient monitoring is required, along with appropriate blood product use. Cell salvage should be considered in all cases where significant blood loss (>1000 ml) is expected or possible, where patients refuse allogeneic blood products or they are anaemic. The use of cell salvage in combination with a leucocyte depletion filter appears to be safe in obstetrics and cases of malignancy; however, further trials are required before definitive guidance may be provided. The only absolute contraindication to the use of cell salvage and autologous blood transfusion is patient refusal.

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.

Amniotic Fluid Embolism: A Comparison between Patients Who Survived and Those Who Died

This study aimed to investigate comparative clinical courses for a series of women with amniotic fluid embolism (AFE) and to assess factors associated with patient survival. Clinical courses of nine patients with AFE in a single tertiary centre were reviewed. AFE was diagnosed when a woman presented with typical clinical symptoms accompanied by abnormal laboratory tests (including abnormal coagulation) or at autopsy when fetal debris was found in the maternal pulmonary arteries. Five patients survived and four died. The first clinical manifestations of AFE were variable; dyspnoea was noted in only four patients. Other signs were state of shock, abdominal pain and uterine atony. The mean ± SD interval between the onset of clinical manifestations and treatment was significantly shorter for survivors (48.0 ± 36.3 min) than for non-survivors (137.5 ± 49.7 min). The number of failed organs was significantly fewer for the survivors compared with the non-survivors. AFE was accompanied by a wide variety of clinical manifestations, but early diagnosis and treatment appeared to be the most critical factors associated with survival.

Amniotic fluid embolism

The disastrous entry of amniotic fluid into the maternal circulation leads to dramatic sequelae of clinical events, characteristically referred to as Amniotic fluid embolism (AFE). The underlying mechanism for AFE is still poorly understood. Unfortunately, this situation has very grave maternal and fetal consequences. AFE can occur during labor, caesarean section, dilatation and evacuation or in the immediate postpartum period. The pathophysiology is believed to be immune mediated which affects the respiratory, cardiovascular, neurological and hematological systems. Undetected and untreated it culminates into fulminant pulmonary edema, intractable convulsions, disseminated intravascular coagulation (DIC), malignant arrhythmias and cardiac arrest. Definite diagnosis can be confirmed by identification of lanugo, fetal hair and fetal squamous cells (squames) in blood aspirated from the right ventricle. Usually the diagnosis is made clinically and by exclusion of other causes. The cornerstone of management is a multidisciplinary approach with supportive treatment of failing organs systems. Despite improved modalities for diagnosing AFE, and better intensive care support facilities, the mortality is still high.

Obstetric disorders in the ICU

Obstetric disorders account for 55% to 80% of admissions to the intensive care unit in the obstetric population. Medical conditions are emerging as the leading cause of maternal mortality, partly because of marked improvement in surgical and obstetric care in the developed world. The rise in maternal mortality related to medical conditions can be explained by multiple factors: improved medical care, women with chronic illnesses reaching childbearing years, older age at time of first pregnancy, improved reproductive technologies, and severe medical conditions exacerbated by the physiologic changes of pregnancy. This article reviews obstetric disorders leading to intensive care unit admissions.