Amniotic fluid embolism: analysis of the national registry

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.

Responding to amniotic fluid embolism

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

Trauma in pregnancy

Acute traumatic injury during pregnancy is a significant contributor to maternal and fetal morbidity and mortality in the United States. Motor vehicle accidents are the leading cause of injury-related maternal death, followed by violence and assault. Lack of seat belts or other restraints increases the risks of both maternal and fetal morbidity and mortality. The American College of Obstetricians and Gynecologists recommends proper seat belt use by all pregnant women and screening for domestic abuse. Maternal injury and death from physical abuse is prevalent, and in some communities, homicide is a major cause of pregnancy-associated maternal death. Blunt trauma most often occurs as a result of motor vehicle accidents, whereas penetrating trauma results from gunshots or stabbings. Blunt trauma to the abdomen increases the risk for placental abruption, and direct fetal injury is more likely with penetrating trauma. Management strategies in acute maternal trauma must focus on a thorough assessment of the mother. A coordinated team effort that includes the obstetrician is essential to ensure optimal maternal and fetal outcomes. Imaging studies should not be delayed because of concerns of fetal radiation exposure, because the risk is minimal with usual imaging procedures, especially in mid-to-late pregnancy. The obstetrician should serve in a consultative role if nonobstetric surgical care is required and must also be prepared to intervene on behalf of the mother and the fetus if trauma care is compromised by the pregnancy. Perimortem cesarean delivery should be considered early in the resuscitation of a pregnant trauma victim, especially when fetal viability is a concern. Once the mother is stabilized in the emergency setting, she should be transported for appropriate maternal and fetal observation until both mother and fetus are clear of danger. It is essential that the clinician and staff maintain thorough and accurate documentation and recording of the chronology of events, the maternal and fetal assessment, and the management and outcome of the pregnancy.

Is dinoprostone safe? A report of three maternal deaths

We report three maternal deaths which might be in possible association with the use of intravaginal dinoprostone for cervical ripening and induction of labor. All cases occurred at our institution between January 2006 and December 2007. Uterine atony and profuse bleeding followed by disseminated intravascular coagulation (DIC), characterized by severe hypofibrinogenemia developed shortly after delivery of the first two patients. The third patient developed respiratory symptoms in the active labor followed by hemodynamic changes manifested by tetanic uterine contractions and fetal heart rate decelerations. Cardiac arrest developed in all patients shortly after the occurrence of symptoms with no response to any medical intervention. The pharmacologic induction of labor with dinoprostone may be in association with increased risk of maternal death because of increased risk of postpartum DIC and amnionic fluid embolism. Further investigations seem to be needed.

[Amniotic fluid embolism during curettage for a pregnancy arrest. Case report]

Amniotic fluid embolism is always a serious complication during the peripartum period. We report the case of an amniotic fluid embolism during curettage for a pregnancy arrest at 13 weeks. The diagnosis was confirmed by the presence of epithelial cells into the maternal blood.

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.

Disseminated intravascular coagulation in obstetric disorders and its acute haematological management

As activation of the coagulation pathway is a physiological response to injury, the development of disseminated intravascular coagulation (DIC) is a warning signal to the clinician that the primary pathological disease state is decompensating. In pregnancy, DIC can occur in several settings, which include emergencies such as placental abruption and amniotic fluid embolism as well as complications such as pre-eclampsia. Whilst the acuteness of the event and the proportionality in the coagulant and fibrinolytic responses may vary between these different conditions, a common theme for pregnancy-associated DIC is the pivotal role played by the placenta. Removal of the placenta is the linchpin to treatment in most cases but appropriate blood product support is also key to management. This is necessary because DIC itself can have pathological consequences that translate clinically into a worse prognosis for affected patients. This article will describe how pregnancy-associated DIC can be diagnosed promptly and how treatment should be managed strategically. It also discusses the latest developments in our understanding of haemostatic mechanisms within the placenta and how these may have relevance to new diagnostic approaches as well as novel therapeutic modalities.

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.

The role of the anesthesiologist in management of obstetric hemorrhage

Hemorrhage after childbirth, whether the delivery is vaginal or operative, is a clinical situation where knowledge, communication, and the availability and utilization of resources all play prominent roles. In this article we describe the thought processes and decisions that should occur, and the actions that should be taken by the anesthesiologist in the face of suspected, expected, or unexpected hemorrhage in the labor and delivery suite.

Management of the unconscious pregnant patient

The management of the unconscious pregnant patient encompasses many aspects of obstetrics and critical care. It is not uncommon to have to manage such a patient, therefore one needs to be well prepared. There is a spectrum of altered consciousness, brain death being the most extreme. The causes of unconsciousness can be general or pregnancy specific. It is important to consider the physiological changes in pregnancy when managing these patients. The immediate resuscitative measures are mostly the same as for the nonpregnant with a few modifications. It is important to remember that there are two patients involved and this can complicate management issues. A multidisciplinary approach would be prudent. The intermediate and long-term management should also involve the family. The issues of perimortem and somatic support for foetal maturity are also discussed.

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.

[Practical questions in case of maternal death]

Every year, in France, about 70 women die during their pregnancy or the delivery. Any maternal death during labour is a traumatic event for the medical team and the family. The medical team has to face many "new" problems. We try to identify all the problems which the medical team has to face in front of a maternal death and try to solve them by a medical literature and French laws review. The medical team often feels powerless when a maternal death occurs. This work was made to be a guideline.

Emergencies associated with pregnancy and delivery: peripartum hemorrhage

INTRODUCTION

Peripartum hemorrhage is one of the leading causes of maternal death worldwide (25%).

METHODS

Selective literature review, including international guidelines, for assessment of the causes and optimal management of this condition.

RESULTS

The major causes of hemorrhage are uterine atony, placenta previa, and abruptio placentae. The diagnosis of hemorrhage is suspected from its clinical manifestations and confirmed by ultrasonography. In placenta previa, the placenta is implanted in the lower uterine segment and may cover the internal cervical os. Placenta previa is more common in older and multiparous mothers, as well as in mothers who have previously undergone a cesarean section. Placental abruption is defined as separation of the placenta from the uterine wall before delivery of the infant. The risk factors for this condition include preeclampsia, advanced maternal age, and trauma. When it presents with manifestations of acute blood loss, premature abruption placentae must be diagnosed rapidly and treated without delay to save the life of the mother and child. A rare, but highly lethal, cause of bleeding is amniotic fluid embolism, which manifests itself with sudden and unexplained peripartum respiratory distress and cardiovascular collapse. Amniotic fluid embolism is associated with high fetal and maternal mortality (20% and 60% to 80%, respectively) even when it is optimally treated.

DISCUSSION

Peripartum hemorrhage is an important source of maternal and fetal morbidity and mortality. The prognosis for both mother and child can be markedly improved if the risk factors for hemorrhage are recognized and the problem is treated rapidly and appropriately when it arises.

Successful placement of a right ventricular assist device for treatment of a presumed amniotic fluid embolism

Amniotic fluid embolism is a rare and often fatal complication of pregnancy. We report the successful multidisciplinary management of a woman who developed a coagulopathy from a presumed amniotic fluid embolism after forceps-assisted vaginal delivery requiring recombinant factor VIIa, and pulmonary arterial hypertension requiring a right ventricular assist device.

Incidence and risk factors of amniotic fluid embolisms: a population-based study on 3 million births in the United States

OBJECTIVE

Amniotic fluid embolism (AFE) is a condition occurring during delivery that can lead to severe maternal morbidity and mortality. Given the rarity of its occurrence, current estimates and predictors of the incidence and outcomes are often difficult to obtain.

STUDY DESIGN

We conducted a population-based cohort study on 3 million birth records in the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample from 1999 to 2003 to estimate the incidence and case fatality of AFEs. Logistic regression was used to calculate the odds ratio (OR) and corresponding 95% confidence intervals (CIs) of demographic and obstetrical determinants of AFEs and fatal AFEs.

RESULTS

The overall incidence of AFE was 7.7 per 100,000 births (95% CI 6.7 to 8.7), with a case fatality rate of 21.6% (95% CI 15.5 to 27.6%). AFE was associated with maternal age greater than 35 (OR 2.2, 95% CI 1.5 to 2.1), placenta previa (OR 30.4, 95% CI 15.4 to 60.1), and cesarean delivery (OR 5.7, 95% CI 3.7 to 8.7). Although AFEs were not significantly associated with induction of labor (OR 1.5, 95% CI 0.9 to 2.3), they were associated with preeclampsia, abruptio placentae, and the use of forceps. Among women with an AFE, common demographic or obstetrical determinants were not predictive of maternal mortality.

CONCLUSION

AFE is a rare but serious condition that is associated with advanced maternal age, placental pathologies, and cesarean deliveries. Further research on the treatment of this condition is necessary.

Maternal death in the 21st century: causes, prevention, and relationship to cesarean delivery

OBJECTIVE

We sought to examine etiology and preventability of maternal death and the causal relationship of cesarean delivery to maternal death in a series of approximately 1.5 million deliveries between 2000 and 2006.

STUDY DESIGN

This was a retrospective medical records extraction of data from all maternal deaths in this time period, augmented when necessary by interviews with involved health care providers. Cause of death, preventability, and causal relationship to mode of delivery were examined.

RESULTS

Ninety-five maternal deaths occurred in 1,461,270 pregnancies (6.5 per 100,000 pregnancies.) Leading causes of death were complications of preeclampsia, pulmonary thromboembolism, amniotic fluid embolism, obstetric hemorrhage, and cardiac disease. Only 1 death was seen from placenta accreta. Twenty-seven deaths (28%) were deemed preventable (17 by actions of health care personnel and 10 by actions of non-health care personnel). The rate of maternal death causally related to mode of delivery was 0.2 per 100,000 for vaginal birth and 2.2 per 100,0000 for cesarean delivery, suggesting that the number of annual deaths resulting causally from cesarean delivery in the United States is about 20.

CONCLUSION

Most maternal deaths are not preventable. Preventable deaths are equally likely to result from actions by nonmedical persons as from provider error. Given the diversity of causes of maternal death, no systematic reduction in maternal death rate in the United States can be expected unless all women undergoing cesarean delivery receive thromboembolism prophylaxis. Such a policy would be expected to eliminate any statistical difference in death rates caused by cesarean and vaginal delivery.

A step-by-step diagnosis of exclusion in a twin pregnancy with acute respiratory failure due to non-fatal amniotic fluid embolism: a case report

INTRODUCTION

Respiratory failure may develop during the later stages of pregnancy and is usually associated with tocolysis or other co-existing conditions such as pneumonia, sepsis, pre-eclampsia or amniotic fluid embolism syndrome.

CASE PRESENTATION

We present the case of a 34-year-old healthy woman with a twin pregnancy at 31 weeks and 6 days who experienced acute respiratory failure, a few hours after administration of tocolysis (ritodrine), due to preterm premature rupture of the membranes. Her chest discomfort was significantly ameliorated after the ritodrine infusion was stopped and a Cesarean section was performed 48 hours later under spinal anesthesia; however, 2 hours after surgery she developed severe hypoxemia, hypotension, fever and mild coagulopathy. The patient was intubated and transferred to the intensive care unit where she made a quick and uneventful recovery within 3 days. As there was no evidence for drug- or infection-related thromboembolic or myocardial causes of respiratory failure, we conclude that our patient experienced a rare type of non-fatal amniotic fluid embolism.

CONCLUSION

In spite of the lack of solid scientific support for our diagnosis, we conclude that our patient suffered an uncommon type of amniotic fluid embolism syndrome and we believe that this report highlights the need for extreme vigilance and a high index of suspicion for such a diagnosis in any pregnant individual.

Multidisciplinary management of placenta percreta complicated by embolic phenomena

Hemorrhage and thrombosis are major causes of maternal mortality. This case discusses the management of a woman with placenta percreta complicated by intraoperative pulmonary embolism. A 39-year-old gravida 3 with two previous cesarean deliveries presented at 34 weeks of gestation with an antepartum hemorrhage. Magnetic resonance imaging confirmed placenta percreta. The multidisciplinary group including obstetricians, gynecological oncologists, interventional radiologists and anesthesiologists developed a delivery plan. Cesarean delivery was performed with internal iliac artery occlusion and embolization catheters in place. After the uterine incision our patient experienced acute hypotension and hypoxia associated with a drop in the end-tidal carbon dioxide and sinus tachycardia. She was resuscitated and the uterus closed with the placenta in situ. Postoperatively, uterine bleeding was arrested by immediate uterine artery embolization. With initiation of embolization, hypotension and hypoxia recurred. Oxygenation and hemodynamics slowly improved, the case continued and the patient was extubated uneventfully at the end of the procedure. Computed tomography revealed multiple pulmonary emboli. The patient was anticoagulated with low-molecular-weight heparin and returned six weeks later for hysterectomy. Placenta percreta with invasion into the bladder can be catastrophic if not recognized before delivery. The chronology of events suggests that this may have been amniotic fluid emboli. An intact placenta with abnormal architecture, such as placenta percreta, may increase the risk of amniotic fluid embolus. The clinical findings and co-existing filling defects on computed tomography may represent a spectrum of amniotic fluid embolism syndrome.

Cell salvage in obstetrics

The safety of cell salvage in obstetrics has been questioned because of the presumed risk of precipitating amniotic fluid embolism and, to a lesser extent, maternal alloimmunisation. For these reasons, experience in this field is limited and has lagged far behind that in other surgical specialties. There has, however, been renewed interest in its use over recent years, mainly as a result of problems associated with allogeneic blood transfusion. Our aim was to review the medical literature to ascertain the principles of cell salvage, the ability of the process to remove contaminants, and its safety profile in the obstetric setting. The search engines PubMed and Google Scholar were used and relevant articles and websites hand searched for further references. Existing cell salvage systems differ in their ability to clear contaminants and all require the addition of a leucocyte depletion filter. Although large prospective trials of cell salvage with autotransfusion in obstetrics are lacking, to date, no single serious complication leading to poor maternal outcome has been directly attributed to its use. Cell salvage in obstetrics has been endorsed by several bodies based on current evidence. Current evidence supports the use of cell salvage in obstetrics, which is likely to become increasingly commonplace, but more data are required concerning its clinical use.

Anaphylactoid syndrome of pregnancy immediately after intrauterine pressure catheter placement

A 35-year-old multipara woman underwent intrauterine pressure catheter placement during labor. Immediately afterwards, she had severe dyspnea develop, became unresponsive, and had a prolonged fetal bradycardia. During emergency cesarean section, she required cardiopulmonary resuscitation repetitively. She then had disseminated intravascular coagulopathy develop and underwent hysterectomy. Anaphylactic reaction may be associated with intrauterine pressure catheter placement.

Cardiopulmonary resuscitation in pregnancy

Although pregnancy and delivery in the United States are usually safe for mother and her newborn child, serious maternal complications, including cardiac arrest, can occur in the prenatal, intrapartum and postpartum periods. The clinical obstetrician can expect to encounter this complication in his or her career. The obstetrician must be aware of the special circumstances of resuscitation of the gravid woman to assist emergency medicine and critical care physicians in reviving the patient. Understanding the decision process leading to the performance of a perimortem cesarean and the actual performance of the cesarean delivery clearly are the responsibility of the obstetrician.

Blood component therapy in obstetrics

Hemorrhage is the leading cause of intensive care unit admission and one of the leading causes of death in the obstetric population. This emphasizes the importance of a working knowledge of the indications for and complications associated with blood product replacement in obstetric practice. This article provides current information regarding preparation for and administration of blood products, discusses alternatives to banked blood in the obstetric population, and introduces pharmacological strategies for treatment of hemorrhage.

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

Nonhemorrhagic primary obstetric shock

OBJECTIVE

Clinical evaluation of nonhemorrhagic primary obstetric shock (NHPOS).

METHODS

In a retrospective clinical study, data on 8 cases of NHPOS were analyzed. Data on patient age, parity, week of gestation, comorbidity, possible etiologic trigger, course of disease with clinical picture and laboratory findings of coagulopathy, and patient outcome including autopsy findings in two lethal outcomes were analyzed.

RESULTS

These 8 patients were treated in the intensive care unit. One patient died during delivery from cardiopulmonary arrest in the state of irreversible obstetric shock, verified by massive pulmonary thromboembolism at autopsy. Another patient died from stroke and cerebral coma caused by trophoblastic cerebrovascular embolism 5 days after artificial abortion, showing a clinical picture of shock and cardiopulmonary arrest. In 1 patient, severe septic shock developed several hours after premature stillbirth and abruptio placentae in the 26th week of pregnancy, associated with disseminated intravascular coagulopathy. Four patients developed intrapartum NHPOS, with a clinical picture of chest pain, dyspnea, tachycardia, hypotension, cyanosis, and disseminated intravascular coagulopathy, as demonstrated by laboratory findings. Based on clinical picture and laboratory findings, amniotic fluid embolism or trophoblastic embolism was suspected. All these patients survived. One patient developed NHPOS during the third labor stage after vacuum extraction because of a macrosomic child, followed by disseminated intravascular coagulopathy and secondary hemorrhage which necessitated B-Lynch procedures and total hysterectomy for massive bleeding. Hereditary thrombophilia was detected in subsequent patients.

CONCLUSIONS

NHPOS can be caused by amniotic fluid embolism, trophoblastic embolism or thromboembolism, and sepsis. These conditions may frequently prove fatal due to their abrupt and unexpected course, mostly during pregnancy, delivery, or immediately thereafter.

Reversible posterior leukoencephalopathy syndrome

Reversible posterior leukoencephalopathy syndrome (RPLS) is a neurological disorder characterized by signs of posterior cerebral edema upon radiographic examination. RPLS has been strongly associated with abrupt and significant elevations in blood pressure or the administration of immunosuppressive drugs. Here, we report a case of RPLS occurring in a 30-year-old-mother with a presumed amniotic fluid embolism subsequent to delivery by cesarean section. On the fifth day after the initial successful resuscitation from the cardiorespiratory collapse, she manifested generalized seizure activity and abnormal radiological findings, which were found to be consistent with RPLS. Through our experience, we have suggested that RPLS might occur more easily at lower blood pressures than has been previously recognized. It is important to consider the lower limit at which blood pressure is controlled, especially if accompanied with fever.

Amniotic fluid embolism managed with success during labour: report of a severe clinical case and review of literature

BACKGROUND

AFE (amniotic fluid embolism) is widely known as a disastrous rapid-progressing clinical entity. The incident ranges from 1:800 to 1:8,000. The mortality rate reaches 61-86%. Neonatal survival is reported at 70%.

METHODS

We describe the case of a healthy 29-year old primigravida developing amniotic fluid embolism during labour. Acute respiratory failure and hypotension combined with seizures were the initial symptoms. The patient under went an urgent caesarean section with extreme blood loss, complicated by disseminated coagulopathy.

RESULTS

A total hysterectomy was performed due to profuse bleeding. Aggressive management was practiced with continuous transfusion of blood products and administration of vasocopressors.

CONCLUSION

Amniotic fluid embolism or anaphylactoid syndrome of pregnancy is a life-threatening condition. Diagnosis is one of the exclusion. Its management is very difficult and requires quick management and cooperation of physicians from different specialties.

Closing the gap between decision and delivery—Amniotic fluid embolism with severe cardiopulmonary and haemostatic complications with a good outcome

Perimortem caesarean section is very rare, mostly resulting in high mortality of mother and/or fetus. We report a case of successful resuscitation of both mother and newborn following maternal cardiac arrest prior to delivery. Postoperative outcome was complicated by severe bleeding and coagulopathy following fibrinolysis and subcapsular hepatic haematoma. We consider a fast reaction time based on a special in-hospital emergency team for immediate caesarean section and an aggressive management of coagulopathy as major factors that led to both patients recovery without neurological sequelae.

Blood conservation techniques in obstetrics: a UK perspective

In the UK, maternal mortality due to haemorrhage appears to be rising, with obstetric haemorrhage accounting for 3-4% of the red cells transfused. Allogeneic blood transfusion carries risks such as administration errors, transmitted infections and immunological reactions. The supply of blood is decreasing, partly due to the exclusion of donors who have themselves received a blood transfusion since 1980, in order to stop transmission of variant-Creutzfeldt-Jakob disease. The cost of blood is significantly increasing, partly because it is now leucocyte-depleted to minimize viral transmission. Various blood conservation techniques can reduce exposure to allogeneic blood thereby reducing risk and conserving the blood supply. These include preoperative autologous donation, acute normovolaemic haemodilution and intra-operative cell salvage. Preoperative autologous donation may produce anaemia, does not eliminate transfusion risk, cannot be used in an emergency and is not acceptable to Jehovah's Witnesses. It should be reserved for exceptional circumstances (rare blood type or unusual antibodies). Acute normovolaemic haemodilution may induce anaemia and cardiac failure and cannot be used in an emergency. It may have a limited role in combination with other techniques. Intra-operative cell salvage is more effective and useful in obstetrics than the other techniques, overcomes their shortcomings and is endorsed by CEMACH, OAA/AAGBI Guidelines, the National Blood Service and NICE.

Anticipating and responding to obstetric emergencies

During the last 10 years, international attention has focused on the importance of medical errors and patient safety. When obstetric emergencies occur, effective and efficient care is essential for good outcome and safety. This chapter presents a framework for obstetric safety, reviews the impact of obstetric emergencies on global health, and discusses possible interventions to improve the anticipation of and responses to obstetric emergencies.

Rapid reversal of critical haemodynamic compromise with nitric oxide in a parturient with amniotic fluid embolism

We describe a case of amniotic fluid embolism presenting as cardiovascular collapse during labour. After initial resuscitation and emergency caesarean section, the patient was transferred to the intensive care unit with profound hypoxaemia, a high inotropic drug requirement and severe coagulopathy. A transoesophageal echocardiogram demonstrated acute right ventricular overload, severe pulmonary artery hypertension and marked diastolic dysfunction of the left ventricle secondary to a dilated right ventricle. The introduction of nitric oxide at 40 ppm produced a dramatic improvement in her cardiorespiratory status. Mother and baby both survived with no apparent long term sequelae.

Critical care of the obstetric patient

The obstetric patient poses exceptional challenges in the intensive care unit. Knowledge of the physiologic changes of pregnancy and specific pregnancy-related disorders is necessary for optimal management. Intensive care unit diagnoses may include preeclampsia, including the HELLP syndrome, pulmonary embolic disease, amniotic fluid embolism, status asthmaticus, respiratory infection, the acute respiratory distress syndrome, and sepsis. The management of mechanical ventilation is based on principles of avoiding lung injury, and hypercapnia may be tolerated even during the pregnancy. When the clinician is faced with the extraordinary instance of cardiopulmonary arrest, perimortem cesarean delivery must be considered to improve the potential for maternal and fetal survival.

Delayed presentation of amniotic fluid embolism: Lessons from a case diagnosed at autopsy

Amniotic fluid embolism (AFE) syndrome, a catastrophic cause of respiratory failure typically occurs during labour, or soon after delivery. Systemic hypotension is the most prominent haemodynamic alteration documented in patients with AFE, a consequence principally of severe left-sided heart failure. A 22-year-old female was admitted to the respiratory intensive care unit with severe eclampsia and acute respiratory failure 4 h following delivery. Her blood pressure was elevated (systolic 150-180 mm Hg, diastolic 90-110 mm Hg) throughout the admission. She succumbed in spite of therapy for eclampsia and mechanical ventilation. Autopsy revealed large numbers of polygonal, anucleate foetal squames and mucin in the pulmonary vasculature typical of AFE while changes of eclampsia were found in the liver and kidneys. It appears that AFE syndrome can have a delayed presentation, as late as 4 h after delivery and haemodynamic collapse may not be mandatory if the patient has coexisting systemic hypertension secondary to severe eclampsia.