Effect of amniotic fluid on coagulation and platelet function in pregnancy: an evaluation using thromboelastography

SHock-INduced Endotheliopathy (SHINE): A mechanistic justification for viscoelastography-guided resuscitation of traumatic and non-traumatic shock

Irrespective of the reason for hypoperfusion, hypocoagulable and/or hyperfibrinolytic hemostatic aberrancies afflict up to one-quarter of critically ill patients in shock. Intensivists and traumatologists have embraced the concept of SHock-INduced Endotheliopathy (SHINE) as a foundational derangement in progressive shock wherein sympatho-adrenal activation may cause systemic endothelial injury. The pro-thrombotic endothelium lends to micro-thrombosis, enacting a cycle of worsening perfusion and increasing catecholamines, endothelial injury, de-endothelialization, and multiple organ failure. The hypocoagulable/hyperfibrinolytic hemostatic phenotype is thought to be driven by endothelial release of anti-thrombogenic mediators to the bloodstream and perivascular sympathetic nerve release of tissue plasminogen activator directly into the microvasculature. In the shock state, this hemostatic phenotype may be a counterbalancing, yet maladaptive, attempt to restore blood flow against a systemically pro-thrombotic endothelium and increased blood viscosity. We therefore review endothelial physiology with emphasis on glycocalyx function, unique biomarkers, and coagulofibrinolytic mediators, setting the stage for understanding the pathophysiology and hemostatic phenotypes of SHINE in various etiologies of shock. We propose that the hyperfibrinolytic phenotype is exemplified in progressive shock whether related to trauma-induced coagulopathy, sepsis-induced coagulopathy, or post-cardiac arrest syndrome-associated coagulopathy. Regardless of the initial insult, SHINE appears to be a catecholamine-driven entity which early in the disease course may manifest as hyper- or hypocoagulopathic and hyper- or hypofibrinolytic hemostatic imbalance. Moreover, these hemostatic derangements may rapidly evolve along the thrombohemorrhagic spectrum depending on the etiology, timing, and methods of resuscitation. Given the intricate hemochemical makeup and changes during these shock states, macroscopic whole blood tests of coagulative kinetics and clot strength serve as clinically useful and simple means for hemostasis phenotyping. We suggest that viscoelastic hemostatic assays such as thromboelastography (TEG) and rotational thromboelastometry (ROTEM) are currently the most applicable clinical tools for assaying global hemostatic function-including fibrinolysis-to enable dynamic resuscitation with blood products and hemostatic adjuncts for those patients with thrombotic and/or hemorrhagic complications in shock states.

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.

A description of the coagulopathy characteristics in amniotic fluid embolism: a case report

Amniotic fluid embolism is frequently associated with coagulopathy. However, the exact nature and evolution of the bleeding disorder is incompletely understood. We report a case of clinically diagnosed amniotic fluid embolism associated with major haemorrhage and coagulopathy. We measured sequential levels of all individual clotting factors, thrombin generation, fibrinogen, and D-dimer levels over the course of the event, beginning shortly after the patient's initial collapse and during the subsequent resuscitation, to identify the specific abnormalities of coagulation from stored blood samples. A better understanding of amniotic fluid embolism and the associated coagulopathy is an important area of research to inform targeted treatment of the coagulopathy and improve outcomes for patients.

Viscoelastic Hemostatic Assays for Postpartum Hemorrhage

This article discusses the importance and effectiveness of viscoelastic hemostatic assays (VHAs) in assessing hemostatic competence and guiding blood component therapy (BCT) in patients with postpartum hemorrhage (PPH). In recent years, VHAs such as thromboelastography and rotational thromboelastometry have increasingly been used to guide BCT, hemostatic adjunctive therapy and prohemostatic agents in PPH. The three pillars of identifying hemostatic competence include clinical observation, common coagulation tests, and VHAs. VHAs are advantageous because they assess the cumulative contribution of all components of the blood throughout the entire formation of a clot, have fast turnaround times, and are point-of-care tests that can be followed serially. Despite these advantages, VHAs are underused due to poor understanding of correct technique and result interpretation, a paucity of widespread standardization, and a lack of large clinical trials. These VHAs can also be used in cases of uterine atony, preeclampsia, acute fatty liver of pregnancy, amniotic fluid embolism, placental abruption, genital tract trauma, surgical trauma, and inherited and prepartum acquired coagulopathies. There exists an immediate need for a point-of-care test that can equip obstetricians with rapid results on developing coagulopathic states. The use of VHAs in predicting and treating PPH, although in an incipient state, can fulfill this need.

Fibrinogen may aid in the early differentiation between amniotic fluid embolism and postpartum haemorrhage: a retrospective chart review

This study aimed to determine whether blood loss and fibrinogen can differentiate amniotic fluid embolism (AFE) from postpartum haemorrhage (PPH). This retrospective case–control study included nine patients with clinical AFE (“AFE group”) and 78 patients with PPH managed at our tertiary care perinatal centre between January 2014 and March 2016. Patients meeting the Japanese diagnostic criteria for AFE were stratified into cardiopulmonary collapse-type AFE and disseminated intravascular coagulation (DIC)-type AFE groups. The relationship between blood loss and fibrinogen at onset was examined to compare DIC severity. Vital signs at onset were not significantly different. The AFE group had significantly less blood loss at onset (1506 mL vs 1843 mL, P = 0.0163), significantly more blood loss 2 h post-onset (3304 mL vs 1996 mL, P < 0.0001) and more severe coagulopathy and fibrinolysis. The blood loss/fibrinogen (B/F) ratio at onset was significantly higher in the DIC-type AFE group (23.15 ± 8.07 vs 6.28 ± 3.35 mL dL/mg, P < 0.0001). AFE was complicated by catastrophic DIC irrespective of blood loss at onset. Fibrinogen exhibited the strongest correlation among test findings at onset. The B/F ratio may help differentiate PPH from DIC-type AFE and diagnose clinical AFE, facilitating optimal replacement of coagulation factors during the early stages.

Systematic review of viscoelastic testing (TEG/ROTEM) in obstetrics and recommendations from the women's SSC of the ISTH

Thromboelastography (TEG) and rotational thromboelastometry (ROTEM) are point-of-care viscoelastic devices that use whole blood samples to assess coagulation and fibrinolysis. These devices have been studied extensively in cardiac surgery, but there is limited robust evidence supporting its use in obstetrics. The hesitancy toward its routine use in obstetrics may be due to the current lack of randomized controlled trials and large observational studies. The study aims to systematically review studies that investigated TEG/ROTEM use in pregnancy or peripartum, and to provide recommendations for future studies to fill current research gaps. We performed a systematic review of studies on viscoelastic testing in obstetrics. Included studies were original research, used TEG or ROTEM during pregnancy or peripartum, and published in English. Ninety-three studies, spanning 31 years from 1989 to 2020 and with a total of 32,817 participants, were included. Sixty-two (66.7%) of the studies used TEG and 31 (33.3%) used ROTEM. To date, there are a total of two randomized controlled trials on TEG/ROTEM use in obstetrics. ROTEM may be used to guide transfusion therapy for postpartum hemorrhage. TEG and ROTEM can detect the hypercoagulable changes associated with pregnancy. Variability between study protocols and results suggests the need for future large prospective high-quality studies with standardized protocols to investigate the utility of TEG/ROTEM in assessing risk for thrombosis and hemorrhage as well as in guiding prophylaxis and treatment in obstetric patients. This review identifies the gaps and provides concrete recommendations for future studies to fill those gaps.

Amniotic fluid embolism-associated coagulopathy: a single-center observational study

INTRODUCTION

Amniotic fluid embolism (AFE) continues to be a rare, enigmatic condition with high maternal mortality. It is characterized by cardiovascular compromise, loss of consciousness or other neurologic symptoms, and coagulopathy. The latter is usually treated according to existing protocols for consumptive coagulopathy.

METHODS

Serial analyses of a panel of hemostaseological parameters were performed in three consecutive cases of AFE that occurred at our institution.

RESULTS

All mothers and neonates survived without major sequelae. Disproportionately low levels of fibrinogen and factor five, and exorbitantly elevated D-dimers were present in all cases, whereas markers of consumptive coagulopathy, platelets and antithrombin in particular, were only slightly reduced.

DISCUSSION

Our results support hyperfibrinolysis as contributing factor of AFE-associated coagulopathy. We, therefore, propose a treatment algorithm which includes early use of tranexamic acid and transfusion of red blood cells and fresh frozen plasma, adding fibrinogen if hemostasis is not readily achieved.

Establishing a reference range for thromboelastography maximum amplitude in patients administrating with antiplatelet drugs

Objective

We aimed to establish the reference range of thromboelastograph (TEG) maximum amplitude (MA) in patients taking antiplatelet drugs.

Methods

Between August 2015 and July 2018, a total of 4614 patients administrating with antiplatelet drugs (clopidogrel and aspirin) were retrospectively analyzed in this study. For MA_A parameter, we used the 10th and 90th percentiles to establish a reference range. The Spearman correlation was used for the correlation analysis among the inhibition rate of adenosine diphosphate (ADP%) and MA_ADP, inhibition rate of arachidonic acid (AA%) and MA_AA. Then, through receiver operating characteristic (ROC) curve analysis of the best cutoff point, the reference ranges of MA_ADP and MA_AA could be deduced. Consistency evaluation was performed by statistical analysis of ADP% and MA_ADP, AA% and MA_AA pairing for 4459 patients.

Results

The reference range of MA_A was 8.1‐25.8 mm. The reference range of MA_ADP was 19.8‐43.2 mm, and the corresponding sensitivity of two endpoints was 0.796, 0.856 and specificity were 0.897, 0.904, respectively. The reference range of MA_AA was 18.9‐37.7 mm, and the corresponding sensitivity of two endpoints was 0.819, 0.829 and specificity were 0.922, 0.896, respectively. The inconsistency rate of ADP% and MA_ADP, and AA% and MA_AA was 20.1% (898 cases) and 16.6% (738 cases), respectively.

Conclusions

The reference range of MA_ADP and MA_AA established by us were better in sensitivity and specificity. MA_ADP and MA_AA were more accurate than conventional inhibition rate analysis in guidance of antiplatelet therapy, especially in patients with excessive low MA or high MA_A.

Amniotic fluid as a potent activator of blood coagulation and platelet aggregation: Study with rotational thromboelastometry

INTRODUCTION

Pulmonary thromboembolism (PTE) is a leading cause of maternal death and frequently occurs during early puerperium. Amniotic fluid components are frequently observed in the maternal circulation in parturition; however, it currently remains unclear whether amniotic fluid contamination in maternal blood is related to the high incidence of PTE in early postpartum.

OBJECTIVES

To examine the influence of amniotic fluid on blood coagulation and fibrinolysis systems with thromboelastometry.

MATERIALS AND METHODS

Twenty-one pregnant women were recruited. We used whole citrated blood in ROTEM® (Tem Innovations GmbH, Munich, Germany), including the non-activated assay (NATEM), assessments for extrinsic (EXTEM) and intrinsic pathways (INTEM), fibrin polymerization (FIBTEM), and hyperfibrinolysis (APTEM), with amniotic fluid contamination, and measured the clotting time (CT), clot formation time (CFT), alpha, amplitude at 10 min (A10), maximum clot firmness (MCF), and lysis indices at 30 min (LI30) and 60 min (LI60).

RESULTS

Short CT in all assays as well as short CFT, high alpha, and increased A10 and MCF in NATEM were observed with amniotic fluid contamination. A10 and MCF as well as LI30 and LI60 decreased in EXTEM. Decreased LI60 with the mixture of amniotic fluid was not improved by tranexamic acid in APTEM.

CONCLUSIONS

Amniotic fluid accelerated thrombin production and activated platelet aggregation without inducing hyperfibrinolysis in whole blood. The activated tissue factor pathway with amniotic fluid produced soft and fragile clots due to its influence on platelets, which may be associated with, at least partly, the high incidence of PTE in early puerperium, particularly after cesarean section.

Procoagulant extracellular vesicles in amniotic fluid

Embolization of amniotic fluid (AF) into the blood circulation leads to disseminated intravascular coagulation (DIC). Procoagulant phosphatidylserine (PS)- and tissue factor (TF)-exposing extracellular vesicles (EVs) might play an important role in AF embolism-induced DIC. It was the aim of the present study to perform analyses of the procoagulant properties of AF with a panel of functional coagulation assays and flow cytometry. We applied a prothrombinase assay (that quantifies PS exposure on EVs), an EV-associated TF activity assay, a fibrin generation assay, a thrombin generation assay, a whole blood clotting model, and flow cytometry in AF and control plasma. We found that PS exposure on EVs was 21-fold increased in AF compared with plasma. Also, EV-associated TF activity was highly increased in AF compared with plasma. AF-derived EVs activated the blood coagulation cascade via PS and TF in the fibrin and thrombin generation assays. In a whole blood clotting model, AF-derived EVs significantly shortened the clotting time from 734 ± 139 seconds in the presence to 232 ± 139 seconds in the absence of an anti-TF antibody. The contact activation pathway via factor XII (FXII) was not affected. Applying flow cytometry, a subpopulation of PS⁺ and TF⁺ EVs was identified in AF but not in control plasma. In conclusion, we investigated the effect of AF on blood coagulation and found that PS⁺ and TF⁺ EVs determine their procoagulant potential. Taken together, our data further delineate the pathomechanisms underlying AF-induced coagulopathy.

Amniotic Fluid Embolism with Isolated Coagulopathy: A Report of Two Cases

Amniotic Fluid Embolism (AFE) is a catastrophic complication of pregnancy with high mortality rate. The most common clinical presentation is an abrupt onset of cardiopulmonary collapse. Here, we present an uncommon variant involving isolated disseminated intravascular coagulation that developed without antecedent cardiopulmonary disturbances. Both patients developed symptoms soon after delivery. Blood test was sent at 14 minutes postpartum for the second patient due to suspected amniotic fluid embolism. Fetal components were observed in the uterine veins of the lower uterine segments in both cases. Amniotic fluid embolism with disseminated intravascular coagulopathy typically progresses faster than disseminated intravascular coagulopathy associated with other causes and symptoms. It usually develops within two hours of delivery. Prompt recognition and treatment of this entity is crucial to survival.

Assessing the Methodology for Calculating Platelet Contribution to Clot Strength (Platelet Component) in Thromboelastometry and Thrombelastography

The viscoelastic properties of blood clot have been studied most commonly using thrombelastography (TEG) and thromboelastometry (ROTEM). ROTEM-based bleeding treatment algorithms recommend administering platelets to patients with low EXTEM clot strength (e.g., clot amplitude at 10 minutes [A10] <40 mm) once clot strength of the ROTEM® fibrin-based test (FIBTEM) is corrected. Algorithms based on TEG typically use a low value of maximum amplitude (e.g., <50 mm) as a trigger for administering platelets. However, this parameter reflects the contributions of various blood components to the clot, including platelets and fibrin/fibrinogen. The platelet component of clot strength may provide a more sensitive indication of platelet deficiency than clot amplitude from a whole blood TEG or ROTEM® assay. The platelet component of the formed clot is derived from the results of TEG/ROTEM® tests performed with and without platelet inhibition. In this article, we review the basis for why this calculation should be based on clot elasticity (e.g., the E parameter with TEG and the CE parameter with ROTEM®) as opposed to clot amplitude (e.g., the A parameter with TEG or ROTEM®). This is because clot elasticity, unlike clot amplitude, reflects the force with which the blood clot resists rotation within the device, and the relationship between clot amplitude (variable X) and clot elasticity (variable Y) is nonlinear. A specific increment of X (ΔX) will be associated with different increments of Y (ΔY), depending on the initial value of X. When calculated correctly, using clot elasticity data, the platelet component of the clot can provide a valuable insight into platelet deficiency in emergency bleeding.

Hemostatic resuscitation in postpartum hemorrhage - a supplement to surgery

BACKGROUND

Postpartum hemorrhage is a potentially life-threatening albeit preventable condition that persists as a leading cause of maternal death. Identification of safe and cost-effective hemostatic treatment options remains crucial as a supplement to surgery and uterotonic agents.

OBJECTIVE

This review summarizes the background, current evidence and recommendations with regard to the role of fibrinogen, tranexamic acid, prothrombin complex concentrate, desmopressin, and recombinant factor VIIa in the treatment of patients with postpartum hemorrhage. The benefits and evidence behind traditional standard laboratory tests and viscoelastic hemostatic assays, i.e. thromboelastography TEG(®) and thromboelastometry ROTEM(®) , are discussed. In addition we assess and elaborate on the current paradigm and evidence for transfusion of these patients.

DATA SOURCES

Publications between 1994 and 2014 were identified from PubMed, EMBASE, Cochrane Library databases, and ClinicalTrial.gov.

RESULTS

Viscoelastic hemostatic assays were found to provide a real-time continuum of coagulation and fibrinolysis when introduced as a supplement in transfusion management of postpartum hemorrhage. Fibrinogen should be considered when hypofibrinogenemia is identified. Early administration of 1-2 g tranexamic acid is recommended, followed by an additional dose in cases of ongoing bleeding. Uncontrolled hemorrhage requires early balanced transfusion.

CONCLUSION

Despite the lack of conclusive evidence for optimal hemostatic resuscitation in postpartum hemorrhage, the use of viscoelastic hemostatic assays, fibrinogen, tranexamic acid and balanced transfusion therapy may prove to be potentially pivotal in the treatment of postpartum hemorrhage.

Thromboelastography as a part of management of amniotic fluid embolism

Amniotic fluid embolism (AFE) is an obstetrical catastrophe characterized by acute hypotension, hypoxia, and coagulopathy occurring during labor, cesarean section, post-delivery, or during amniocentesis. Thromboelastography (TEG) is a bedside test of global homeostasis and has seldom been used to study coagulation in AFE despite increasing popularity in other diseases. We report TEG usage as part of a treatment for patients with AFE.

Transfusion ratios for postpartum hemodilutional coagulopathy: an in vitro thromboelastographic model

OBJECTIVE

A 1:1:1 ratio of packed red blood cells (PRBC), fresh frozen plasma (FFP), and platelets (PLT) has been advocated for trauma hemorrhage, but the effectiveness of this ratio for postpartum hemorrhage is unknown. We created an in vitro hemodilutional model to investigate this strategy.

STUDY DESIGN

Blood from 20 parturients at term was diluted 50% with 0.9% normal saline. Diluted samples were reconstituted with 1:1 PRBC:FFP or 3:1 PRBC:FFP. In 10 samples, PLT were also added. Baseline, diluted, and reconstituted sample thromboelastographic values were compared.

RESULTS

Maximum amplitude (MA) was lower compared to baseline values in both groups after 50% dilution with normal saline (P < .001) and remained lower than baseline despite reconstitution with 3:1:0 or 1:1:0 PRBC:FFP:PLT (P < .0001) or 3:1:1 PRBC:FFP:PLT (P < .01). MA approached baseline (P = not significant) in the samples with 1:1:1 PRBC:FFP:PLT.

CONCLUSION

The addition of PLT to 1:1 PRBC:FFP optimized MA in this in vitro hemodilutional model of postpartum hemorrhage.

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.

Disseminated intravascular coagulation

Disseminated intravascular coagulation in obstetrics is commonly seen associated with massive hemorrhage due to different etiological factors. It may also be seen with intrauterine demise, infections, and hepatic conditions. It is associated with very high maternal and perinatal morbidity and mortality. A battery of laboratory tests (prothrombin time, partial thromboplastin time, thrombin time, and plasma fibrinogen) can be used in the diagnosis, but no single test in isolation is sensitive and specific enough for diagnosis. Cornerstone of management is to identify the underlying pathology for disseminated intravascular coagulation. This chapter looks into molecular basis of obstetric DIC and identifies important laboratory tests, along with management. It also identifies topics of future research in the field of obstetric DIC.

Haemostatic monitoring during postpartum haemorrhage and implications for management

Postpartum haemorrhage (PPH) is a major risk factor for maternal morbidity and mortality. PPH has numerous causative factors, which makes its occurrence and severity difficult to predict. Underlying haemostatic imbalances such as consumptive and dilutional coagulopathies may develop during PPH, and can exacerbate bleeding and lead to progression to severe PPH. Monitoring coagulation status in patients with PPH may be crucial for effective haemostatic management, goal-directed therapy, and improved outcomes. However, current PPH management guidelines do not account for the altered baseline coagulation status observed in pregnant patients, and the appropriate transfusion triggers to use in PPH are unknown, due to a lack of high-quality studies specific to this area. In this review, we consider the evidence for the use of standard laboratory-based coagulation tests and point-of-care viscoelastic coagulation monitoring in PPH. Many laboratory-based tests are unsuitable for emergency use due to their long turnaround times, so have limited value for the management of PPH. Emerging evidence suggests that viscoelastic monitoring, using thrombelastography- or thromboelastometry-based tests, may be useful for rapid assessment and for guiding haemostatic therapy during PPH. However, further studies are needed to define the ranges of reference values that should be considered ‘normal’ in this setting. Improving awareness of the correct application and interpretation of viscoelastic coagulation monitoring techniques may be critical in realizing their emergency diagnostic potential.

Comparison of whole blood fibrin-based clot tests in thrombelastography and thromboelastometry

BACKGROUND

Fibrin-based clot firmness is measured as maximum amplitude (MA) in the functional fibrinogen (FF) thrombelastographic assay and maximum clot firmness (MCF) in the FIBTEM thromboelastometric assay. Differences between the assays/devices may be clinically significant. Our objective was to compare clot firmness parameters through standard (FF on a thrombelastography device [TEG®]; FIBTEM on a thromboelastometry device [ROTEM®]) and crossover (FF on ROTEM®; FIBTEM on TEG®) analyses.

METHODS

Whole-blood samples from healthy volunteers were subjected to thrombelastography and thromboelastometry analyses. Samples were investigated native and following stepwise dilution with sodium chloride solution (20%, 40%, and 60% dilution). Samples were also assessed after in vitro addition of medications (heparin, protamine, tranexamic acid) and 50% dilution with hydroxyethyl starch, gelatin, sodium chloride, and albumin.

RESULTS

FF produced higher values than FIBTEM, regardless of the device, and TEG® produced higher values than ROTEM®, regardless of the assay. With all added medications except heparin 400 U/kg bodyweight, FF MA remained significantly higher (P < 0.05) than FIBTEM MCF, which was largely unchanged. FF MA was significantly reduced (P = 0.04) by high-dose heparin and partially restored with protamine. Fifty percent dilution with hydroxyethyl starch, albumin, and gelatin decreased FIBTEM MCF and FF MA by >50%.

CONCLUSIONS

These results demonstrate differences when measuring fibrin-based clotting via the FF and FIBTEM assays on the TEG® and ROTEM® devices. Point-of-care targeted correction of fibrin-based clotting may be influenced by the assay and device used. For the FF assay, data are lacking.

Activation of coagulation in amniotic fluid during normal human pregnancy

INTRODUCTION

Amniotic fluid (AF) is an important medium for fetal development which exhibits high procoagulant activities; however, the role of these procoagulants during pregnancy has not been elucidated and might be associated with pregnancy complications. The current study aimed to evaluate factor X (FX) activation and its association with tissue factor (TF), tissue factor pathway inhibitor (TFPI) and coagulation activation markers in AF during normal human pregnancy.

METHODS

Activation of FX and concentration of TF, free TFPI, D-dimer and prothrombin fragments (F1+2) were evaluated in AF samples obtained for chromosome analysis from 91 women with normal pregnancy: 65 samples were taken from patients at 16-20 weeks of gestation, 9 samples were drawn at 21-30 weeks and 17 samples--after 30 weeks of gestation.

RESULTS

Activation of FX in AF significantly increased during normal pregnancy (from 65±41 to 205±80 equivalent RVV ng/mg total protein, P<0.0001). TF and TFPI levels in AF also rose with gestational age. In contrast, the AF concentration of D-dimer and F1+2, markers of coagulation activation significantly decreased when expressed per mg total protein. Levels of free TFPI correlated with TF (r=0.5, P<0.001), and were 8-fold higher than those of TF during pregnancy.

CONCLUSION

High levels of TFPI might be associated with the inhibition of procoagulant activity in amniotic fluid during normal pregnancy, which may account for the rarity of clinical amniotic fluid embolism.

Surgical treatment of an amniotic fluid embolism with cardiopulmonary collapse

Amniotic fluid embolism is a rare but devastating condition associated with a very high rate of morbidity and mortality. The treatment has traditionally been aggressive supportive care. We report a case of a term pregnant woman with complete cardiovascular collapse secondary to a paradoxical amniotic fluid embolism. The embolism was seen on transesophageal echocardiogram during an emergency Cesarean section as a free-floating interatrial clot through a patent foramen ovale. She was subsequently and successfully treated with immediate cardiopulmonary bypass, thromboembolectomy, and closure of the patent foramen ovale.

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.

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.

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.