Reference ranges for thromboelastography (TEG(®) ) and traditional coagulation tests in term parturients undergoing caesarean section under spinal anaesthesia*

Management of severe peri-operative bleeding: Guidelines from the European Society of Anaesthesiology and Intensive Care: Second update 2022

BACKGROUND

Management of peri-operative bleeding is complex and involves multiple assessment tools and strategies to ensure optimal patient care with the goal of reducing morbidity and mortality. These updated guidelines from the European Society of Anaesthesiology and Intensive Care (ESAIC) aim to provide an evidence-based set of recommendations for healthcare professionals to help ensure improved clinical management.

DESIGN

A systematic literature search from 2015 to 2021 of several electronic databases was performed without language restrictions. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used to assess the methodological quality of the included studies and to formulate recommendations. A Delphi methodology was used to prepare a clinical practice guideline.

RESULTS

These searches identified 137 999 articles. All articles were assessed, and the existing 2017 guidelines were revised to incorporate new evidence. Sixteen recommendations derived from the systematic literature search, and four clinical guidances retained from previous ESAIC guidelines were formulated. Using the Delphi process on 253 sentences of guidance, strong consensus (>90% agreement) was achieved in 97% and consensus (75 to 90% agreement) in 3%.

DISCUSSION

Peri-operative bleeding management encompasses the patient's journey from the pre-operative state through the postoperative period. Along this journey, many features of the patient's pre-operative coagulation status, underlying comorbidities, general health and the procedures that they are undergoing need to be taken into account. Due to the many important aspects in peri-operative nontrauma bleeding management, guidance as to how best approach and treat each individual patient are key. Understanding which therapeutic approaches are most valuable at each timepoint can only enhance patient care, ensuring the best outcomes by reducing blood loss and, therefore, overall morbidity and mortality.

CONCLUSION

All healthcare professionals involved in the management of patients at risk for surgical bleeding should be aware of the current therapeutic options and approaches that are available to them. These guidelines aim to provide specific guidance for bleeding management in a variety of clinical situations.

Emerging technology for early detection and management of postpartum hemorrhage to prevent morbidity

Despite advances in hemorrhage detection and management, postpartum hemorrhage remains the single leading cause of maternal death worldwide. Within the United States, hemorrhage is the leading cause of maternal death on the day of delivery and within the first week after delivery. Blood transfusion after hemorrhage represents a large proportion of severe maternal morbidity during and after delivery. Blood loss during delivery has historically been assessed visually by inspecting soiled pads, linens, and laparotomy sponges. These methods underestimate the volume of blood loss by as much as 40%, becoming increasingly inaccurate as blood loss increases. Young, healthy obstetrical patients compensate for blood loss via peripheral vasoconstriction, maintaining heart rate and blood pressure in a normal range until over 1 L of blood has been lost. A significant decrease in blood pressure along with marked tachycardia (>120 bpm) may not be seen until 30% to 40% of blood volume has been lost, or 2.0 to 2.6 L in a healthy term pregnant patient, after which the patient may rapidly decompensate. In resource-poor settings especially, the narrow window between the emergence of significant vital sign abnormalities and clinical decompensation may prove catastrophic. Once hemorrhage is detected, decisions regarding blood product transfusion are routinely made on the basis of inaccurate estimates of blood loss, placing patients at risk of underresuscitation (increasing the risk of hemorrhagic shock and end-organ damage) or overresuscitation (increasing the risk of transfusion reaction, fluid overload, and alloimmunization). We will review novel technologies that have emerged to assist both in the early and accurate detection of postpartum hemorrhage and in decisions regarding blood product transfusion.

Risk stratification for pregnancy-associated venous thromboembolism: Potential role for global coagulation assays

Risk assessment for venous thromboembolism in pregnancy and the puerperium is currently limited to stratifying clinical surrogate risk factors without high-quality evidence. While the absolute risk of pregnancy-associated venous thromboembolism is low for the vast majority of women, associated morbidity and mortality remains significant. As guidelines for thromboprophylaxis vary widely, some women may be under- or over-anticoagulated, contributing to poor outcomes. New global coagulation assays provide a holistic view of coagulation and may have the potential to detect hypercoagulability in pregnancy, unlike clinically available coagulation assays. However, there are major technical challenges to overcome before global coagulation assays can be realistically proposed as an adjunct to risk assessment for pregnancy-associated venous thromboembolism. This review summarises the literature and controversies in the prediction and prevention of pregnancy-associated venous thromboembolism and outlines the new tools in haematology that may assist in our future understanding of hypercoagulability in pregnancy.

Pro-Con Debate: Viscoelastic Hemostatic Assays Should Replace Fixed Ratio Massive Transfusion Protocols in Trauma

Major trauma patients at risk of traumatic coagulopathy are commonly treated with early clotting factor replacement to maintain hemostasis and prevent microvascular bleeding. In the United States, trauma transfusions are often dosed by empiric, low-ratio massive transfusion protocols, which pair plasma and platelets in some ratio relative to the red cells, such as the "1:1:1" combination of 1 units of red cells, 1 unit of plasma, and 1 donor's worth of pooled platelets. Empiric transfusion increases the rate of overtransfusion when unnecessary blood products are administered based on a formula and not on at patient's hemostatic profile. Viscoelastic hemostatic assays (VHAs) are point-of-care hemostatic assays that provided detailed information about abnormal clotting pathways. VHAs are used at many centers to better target hemostatic therapies in trauma. This Pro/Con section will address whether VHA guidance should replace empiric fixed ratio protocols in major trauma.

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.

Thromboelastography (TEG) in normal pregnancy and its diagnostic efficacy in patients with gestational hypertension, gestational diabetes mellitus, or preeclampsia

BACKGROUND

Thromboelastography (TEG) provides global assessment of hemostatic function and has been recommended to monitor potential coagulopathies during pregnancy in which hypercoagulable state is favored. In present study, we established the reference intervals (RIs) of the TEG parameters (R, K, MA, and α-angle) with Chinese pregnant women of third trimester. In addition, we examined the diagnostic efficacies of the TEG parameters in the patients diagnosed of gestational hypertension (GH), gestational diabetes mellitus (GDM), or preeclampsia (PE).

METHODS

With specified including and excluding criteria, non-pregnant controls, healthy pregnant women, and pregnant women with GH, GDM, or PE had their venous blood drawn at Beijing Obstetrics and Gynecology Hospital, followed by TEG tests performed in the clinical laboratory.

RESULTS

The RIs determined with the healthy pregnant women (in third trimester) for R, K, MA, and α-angle were 4.0-7.7, 1.2-3.2, 51.9-70.1, and 41.4-74.4, respectively. When compared with the healthy pregnancy group, the K value was significantly decreased in GH patients but increased in PE patients; MA was significantly lower in the PE group. In the receiver operating characteristic curve (ROC) analyses, K value was able to efficiently distinguish normal pregnancy from the GH patients, with an AUC of 0.86 which is far better than those of R (AUC = 0.57) and MA (AUC = 0.56). For the PE patients, the AUC of MA (0.69) was significantly greater than that of R (0.50).

CONCLUSIONS

Thromboelastography may provide more accurate experimental basis for monitoring coagulation functions especially in pregnant women with complications of GH and PE.

Assessing maternal clotting function with novel global coagulation assays: A prospective pilot study

INTRODUCTION

Women are at higher risk of venous thromboembolism (VTE) during pregnancy and the puerperium. Global coagulation assays (GCAs), including thromboelastography (TEG), thrombin generation using the calibrated automated thrombogram (CAT) and fibrin generation using the overall haemostatic potential assay (OHP), provide a more comprehensive assessment of the coagulation process than conventional coagulation assays. We aimed to evaluate the ability of these GCAs to analyse the coagulability among pregnant women of varying VTE risk profile.

METHODS

Women undergoing term elective caesarean delivery provided a single predelivery blood sample for conventional and novel coagulation testing (TEG, CAT and OHP). Data from 47 healthy nonpregnant women aged 18-45 years were used as controls.

RESULTS

Sixty women with term singleton pregnancies were included. Samples from pregnant women were hypercoagulable on most GCA parameters compared to nonpregnant controls, demonstrating increased maximum amplitude (clot strength) (71.5 vs 60.6 mm, P < .001) on whole blood TEG and increased endogenous thrombin potential (1895.22 vs 1399.33 nmol/L·min, P < .001) and overall coagulation potential (fibrin generation) (57.58 vs 36.21 units, P < .001) on platelet-poor plasma. Pregnant women with booking BMI ≥ 30 kg/m² had significantly higher maximum amplitude compared to pregnant women of normal BMI (18.5-25 kg/m² ) (73.2 vs 66.1 mm, P < .001).

CONCLUSIONS

Global coagulation assays reliably detect the physiological hypercoagulability of pregnancy. Thromboelastography in particular appears to correlate with obesity in the pregnant population. GCAs may be potential adjuncts to risk factor-based criteria to guide VTE thromboprophylaxis during pregnancy and the puerperium.

Thromboelastographic Assessment of Fibrinolytic Activity in Postpartum Hemorrhage: A Retrospective Single-Center Observational Study

BACKGROUND

Postpartum hemorrhage is a leading cause of maternal mortality. Antifibrinolytic therapy has the potential to influence outcomes in postpartum hemorrhage, but the incidence of elevated fibrinolytic activity in postpartum hemorrhage is unknown.

METHODS

We retrospectively reviewed thromboelastography (TEG) results obtained for postpartum hemorrhage from 118 deliveries at The University of Chicago. TEG results were obtained as part of our postpartum hemorrhage protocol when blood loss exceeded 500 mL after vaginal delivery or 1000 mL after cesarean delivery. Our primary outcome was the incidence of elevated fibrinolytic activity, which we predefined as clot lysis ≥3% at 30 minutes (Ly30) on kaolin TEG. Platelet-mediated clot retraction can also lead to an elevated Ly30 on kaolin TEG. Therefore, to distinguish between fibrinolysis and clot retraction, we evaluated clot lysis using functional fibrinogen TEG, which contains a platelet inhibitor. We considered a kaolin TEG Ly30 ≥3% in conjunction with a nonzero functional fibrinogen TEG Ly30 suggestive of elevated fibrinolytic activity. We also recorded quantitative blood loss, primary etiology of hemorrhage, standard laboratory measurements of coagulation, and demographic and obstetric characteristics of the study population.

RESULTS

The median kaolin TEG Ly30 was 0.2% (interquartile range: 0%-0.8%). Fifteen of 118 women (12.7%; 95% confidence interval, 7.9%-19.9%) had kaolin TEG Ly30 values ≥3%. Of 15 patients with elevated Ly30 values, functional fibrinogen TEG Ly30 was available for 13, of which none demonstrated detectable clot lysis.

CONCLUSIONS

Our observation that none of the patients in our sample with kaolin TEG Ly30 values ≥3% had a nonzero functional fibrinogen TEG Ly30 value suggests that the observed elevations in kaolin TEG Ly30 may have been secondary to platelet-mediated clot retraction as opposed to fibrinolysis. Platelet-mediated clot retraction should be distinguished from fibrinolysis when assayed using viscoelastic techniques in postpartum hemorrhage. Further research is necessary to determine the optimal methods to assess fibrinolytic activity in postpartum hemorrhage.

Viscoelastic testing in liver transplantation

Despite the lack of large randomized clinical studies, viscoelastic tests (VETs) have been a critical armamentarium for hemostatic control in liver transplantation (LT) since the 1960s. Many transplant institutions have adopted VETs in their clinical practice. Several small-size randomized clinical trials on LT patients have suggested that VET-guided hemostatic treatment algorithms have led to decreased indications for and amounts of transfused blood products, especially fresh-frozen plasma, compared to standard laboratory-based hemostatic management. VETs have also been reported to offer insight into the diagnosis and prediction of LT patients' development of hypercoagulability-related morbidity and mortality. There is still a need for VET device-specific hemostatic algorithms in LT, and clinicians must take into account the tendency to underestimate the coagulation capacity of VETs in patients with end-stage liver disease where hemostasis is rebalanced.

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.

To Clot or Not: HELLP Syndrome and Disseminated Intravascular Coagulation in an Eclamptic Patient with Intrauterine Fetal Demise

A 39-year-old G2P1001 female presented from an outside hospital following an eclamptic seizure in the setting of HELLP syndrome. This condition was complicated by intrauterine fetal demise and disseminated intravascular coagulation, which required an emergent cesarean section. We report the work-up and intraoperative and postoperative management of this complex patient with multiple medical needs. We focus on the hemostatic abnormalities in this patient and describe how our management would differ from that of a similar, nonpregnant patient.

Point-of-Care Fibrinogen Testing in Pregnancy

Agreement between estimated fibrinogen concentration via thromboelastography and traditional assays is not established in the parturient. We therefore recruited 56 parturients and performed Clauss and functional fibrinogen level (FLEV) tests. Mean difference of measurements was 36.8 mg/dL (95% CI, 21.8-51.9) with a standard deviation of 52.8 mg/dL. Calculated limits of agreement were 140.2 mg/dL (95% CI, 166.3-114.6) and -66.6 mg/dL (95% CI, -40.8 to -92.5), within the maximum allowable difference of 165 mg/dL. We therefore conclude that while most measurements fell within the limits of agreement, more work is needed to clearly define the role of this test in the obstetric population.

Platelets stored in whole blood at 4°C: in vivo posttransfusion platelet recoveries and survivals and in vitro hemostatic function

BACKGROUND

Ordinarily, whole blood (WB) is separated into components before storage. We assessed the posttransfusion viability and function of platelets (PLTs) if they were stored within WB at 4°C.

STUDY DESIGN AND METHODS

Whole blood was obtained from 30 normal subjects and stored at 4°C without agitation for 12 days and for 10, 15, or 22 days with agitation. After WB storage, a PLT concentrate was prepared, and a fresh PLT sample was obtained from each donor. The stored PLTs were labeled with ¹¹¹ In and the fresh with ⁵¹ Cr, and both were simultaneously transfused into their donor. Blood samples were obtained after transfusion to determine PLT recoveries and survivals. PLT samples from WB before and after storage were also assayed for PLT function and biochemistry.

RESULTS

After storage for 12 days without WB rotation, poststorage PLT counts averaged only 49 ± 12% of baseline values. After storage for 10, 15, or 22 days with end-over-end WB rotation, PLT counts averaged 76 ± 14% of baseline values. Fifteen-day poststorage radiolabeled PLT recoveries averaged 27 ± 11% (49 ± 16% of fresh), and survivals averaged 1.2 ± 0.4 days (16 ± 6% of fresh). in vitro assays demonstrated marked PLT activation after any storage time, and although PLT function decreased over time, stored PLTs were still considered acceptable.

CONCLUSION

These data suggest that, during rotated WB storage at 4°C for up to 15 days, PLT yields, poststorage PLT recoveries and survivals, and PLT function should be sufficient to support the short-term hemostatic needs of traumatized patients.

A clinical-scale BioArtificial Liver, developed for GMP, improved clinical parameters of liver function in porcine liver failure

Liver failure, whether arising directly from acute liver failure or from decompensated chronic liver disease is an increasing problem worldwide and results in many deaths. In the UK only 10% of individuals requiring a liver transplant receive one. Thus the need for alternative treatments is paramount. A BioArtificial Liver machine could temporarily replace the functions of the liver, buying time for the patient's liver to repair and regenerate. We have designed, implemented and tested a clinical-scale BioArtificial Liver machine containing a biomass derived from a hepatoblastoma cell-line cultured as three dimensional organoids, using a fluidised bed bioreactor, together with single-use bioprocessing equipment, with complete control of nutrient provision with feedback BioXpert recipe processes, and yielding good phenotypic liver functions. The methodology has been designed to meet specifications for GMP production, required for manufacture of advanced therapy medicinal products (ATMPs). In a porcine model of severe liver failure, damage was assured in all animals by surgical ischaemia in pigs with human sized livers (1.2-1.6 kg liver weights). The BioArtificial liver (UCLBAL) improved important prognostic clinical liver-related parameters, eg, a significant improvement in coagulation, reduction in vasopressor requirements, improvement in blood pH and in parameters of intracranial pressure (ICP) and oxygenation.

Transfusion and coagulation management in major obstetric hemorrhage

PURPOSE OF REVIEW

Major obstetric hemorrhage is a leading cause of maternal morbidity and mortality. We will review transfusion strategies and the value of monitoring the maternal coagulation profile during severe obstetric hemorrhage.

RECENT FINDINGS

Epidemiologic studies indicate that rates of severe postpartum hemorrhage (PPH) in well resourced countries are increasing. Despite these increases, rates of transfusion in obstetrics are low (0.9-2.3%), and investigators have questioned whether a predelivery 'type and screen' is cost-effective for all obstetric patients. Instead, blood ordering protocols specific to obstetric patients can reduce unnecessary antibody testing. When severe PPH occurs, a massive transfusion protocol has attracted interest as a key therapeutic resource by ensuring sustained availability of blood products to the labor and delivery unit. During early postpartum bleeding, recent studies have shown that hypofibrinogenemia is an important predictor for the later development of severe PPH. Point-of-care technologies, such as thromboelastography and rotational thromboelastometry, can identify decreased fibrin clot quality during PPH, which correlate with low fibrinogen levels.

SUMMARY

A massive transfusion protocol provides a key resource in the management of severe PPH. However, future studies are needed to assess whether formula-driven vs. goal-directed transfusion therapy improves maternal outcomes in women with severe PPH.

How I treat postpartum hemorrhage

Worldwide, ∼800 women die every day from preventable causes related to pregnancy or childbirth. The single most common cause is severe bleeding, which can kill a healthy woman within hours if care is substandard or delayed. Improved antenatal practices have led to the early identification of at-risk women and modern technology and new techniques have enabled effective management strategies so that now, in the western world, most of the morbidity and mortality arises from those cases which occur unexpectedly and could not have been predicted. Prompt and effective management and multidisciplinary involvement is paramount to save the lives of these women. We use a case report to illustrate and discuss the main elements of management of this condition.

New approaches to obstetric hemorrhage: the postpartum hemorrhage consensus algorithm

PURPOSE OF REVIEW

Postpartum hemorrhage is increasingly frequent and a major contributor to maternal morbidity and mortality. Although individual steps, such as coagulation or surgical management, have been reviewed, there is little information on treatment algorithms.

RECENT FINDINGS

A treatment algorithm for postpartum hemorrhage was developed by the experts from three different specialties and from three countries. The algorithm describes symptoms, diagnosis, general measurements, medication, and organizational aspects.

SUMMARY

The algorithm is thought to serve as a template for local adaptation. It will hopefully improve the management of postpartum hemorrhage.

[Management of postpartum hemorrhage (PPH): algorithm of the interdisciplinary D-A-CH consensus group PPH (Germany - Austria - Switzerland)]

Postpartum hemorrhage (PPH) is one of the main causes of maternal deaths even in industrialized countries. It represents an emergency situation which necessitates a rapid decision and in particular an exact diagnosis and root cause analysis in order to initiate the correct therapeutic measures in an interdisciplinary cooperation. In addition to established guidelines, the benefits of standardized therapy algorithms have been demonstrated. A therapy algorithm for the obstetric emergency of postpartum hemorrhage in the German language is not yet available. The establishment of an international (Germany, Austria and Switzerland D-A-CH) "treatment algorithm for postpartum hemorrhage" was an interdisciplinary project based on the guidelines of the corresponding specialist societies (anesthesia and intensive care medicine and obstetrics) in the three countries as well as comparable international algorithms for therapy of PPH.The obstetrics and anesthesiology personnel must possess sufficient expertise for emergency situations despite lower case numbers. The rarity of occurrence for individual patients and the life-threatening situation necessitate a structured approach according to predetermined treatment algorithms. This can then be carried out according to the established algorithm. Furthermore, this algorithm presents the opportunity to train for emergency situations in an interdisciplinary team.

What's new in Obstetric Anesthesia? The 2013 Gerard W. Ostheimer lecture

The "What's New in Obstetric Anesthesia?" keynote lecture was established by the Society for Obstetric Anesthesia and Perinatology in memory of the eminent obstetric anesthesiologist, Dr. Gerard W. Ostheimer. From a wide selection of journals encompassing the fields of obstetric anesthesia, obstetrics, and perinatology, the designated lecturer identifies articles of significant impact and interest published in the preceding year. The Ostheimer lecture, delivered this year at the annual meeting of the Society in April 2013 in San Juan, Puerto Rico, included highly relevant papers that have the potential to change obstetric anesthesia practice or impact public health. This review summarizes 5 categories of pertinent articles that were published in 2012 and discussed in the 2013 Ostheimer lecture: maternal diseases, labor and delivery, advances in obstetric anesthesia, obstetric complications, and anesthesia-related complications.

Comparison of in vitro responses to fresh whole blood and reconstituted whole blood after collagen stimulation

BACKGROUND

In patients who have large bleeds, there is a tendency to transfuse more plasma and platelets than recommended in earlier guidelines, and accordingly many hospitals now provide "transfusion packages" with an intended red cell:platelet:plasma ratio of 1:1:1. The purpose of this study was to investigate in vitro functions of transfusion packs compared with fresh whole blood.

MATERIAL AND METHODS

"Reconstituted whole blood" was prepared with the same ratio of red cells, platelets and plasma as used in local transfusion packages. The aggregation and thrombin-antithrombin complex formation responses to collagen stimulation of this reconstituted whole blood were compared with those of fresh whole blood. The storage time of red cells and platelets was varied in a systematic manner, giving nine different compositions of reconstituted whole blood that simulated transfusion packs.

RESULTS

The responses varied significantly between whole blood and reconstituted whole blood -and between the reconstituted whole blood of different compositions. A significant decrease (p<0.005) in collagen-induced platelet count reduction was seen with increasing platelet and red blood cell age. Thrombin-antithrombin complex formation peaked in studies with platelets stored for 5 days. The red cells stored for the longest time induced the greatest thrombin-antithrombin complex formation. Fresh whole blood gives more consistent responses, and the aggregation response to collagen is stronger than in reconstituted whole blood.

DISCUSSION

Our results indicate that in vitro responses of reconstituted whole blood vary substantially according to how long the red cells and platelets are stored for. As the responses obtained by testing whole blood are more consistent and usually stronger, the alternative use fresh whole blood in special conditions should not be excluded without further consideration.

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.