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Factor XII (FXII) is a serine protease zymogen produced by hepatocytes and secreted into plasma. The highly glycosylated coagulation protein consists of six domains and a proline-rich region that regulate activation and function. Activation of FXII results from a conformational change induced by binding ("contact") with negatively charged surfaces. The activated serine protease FXIIa drives both the proinflammatory kallikrein-kinin pathway and the procoagulant intrinsic coagulation cascade, respectively. Deficiency in FXII is associated with a prolonged activated partial thromboplastin time (aPTT) but not with an increased bleeding tendency. However, genetic or pharmacological deficiency impairs both arterial and venous thrombosis in experimental models. This review summarizes current knowledge of FXII structure, mechanisms of FXII contact activation, and the importance of FXII for diagnostic coagulation testing and thrombosis.Faktor XII (FXII) ist das Zymogen der Serinprotease FXIIa, wird von Hepatozyten produziert und ins Plasma sekretiert. Das Plasmaprotein besteht aus sechs Domänen sowie einer Prolin-reichen Region und ist stark glykosyliert. Die Aktivierung von FXII erfolgt durch eine Konformationsänderung, die durch die Bindung (den „Kontakt“) mit negativ geladenen Oberflächen hervorgerufen wird. In der Folge aktiviert FXIIa sowohl das proinflammatorische Kallikrein-Kinin-System, welches Bradykinin produziert, als auch die intrinsische Gerinnungskaskade. Eine FXII-Defizienz oder Dysfunktionalität ist mit einer verzögerten aktivierten partiellen Thromboplastinzeit (aPTT) assoziiert, nicht aber mit einer erhöhten Blutungsneigung. Dennoch zeigen experimentelle Modelle, dass FXII essentiell für die Bildung arterieller und venöser, Gefäß-verschließender Thrombosen ist. Diese Übersichtsarbeit fasst das aktuelle Wissen über die Struktur von FXII, den Mechanismus der FXII-Kontaktaktivierung und die Bedeutung von FXII für diagnostische Gerinnungstests zusammen.

Background Accumulating evidence indicates toward an association between severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and procoagulatory state in blood. Thromboelastographic investigations are useful point-of-care devices to assess coagulation and fibrinolysis.Objectives We investigated the hypothesis that the procoagulatory state in COVID-19 patients is associated with impaired fibrinolysis system.Methods Altogether, 29 COVID-19 patients admitted to normal wards or to the intensive care unit (ICU) were included in this descriptive study. Whole blood samples were investigated by thromboelastography to assess coagulation and fibrinolysis. Additionally, standard routine coagulation testing and immunoassays for factors of fibrinolysis as plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA), plasminogen activity and α2-antiplasmin (A2AP) were performed.Results A significantly increased lysis resistance and a significantly longer time of lysis after adding tissue plasminogen activator were observed in blood samples from ICU COVID-19 patients compared with healthy controls (maximal lysis: 3.25 ± 0.56 vs. 6.20 ± 0.89%, p = 0.0127; lysis time: 365.7 ± 44.6 vs. 193.2 ± 16.3 seconds, p = 0.0014). PAI-1 activity was significantly higher in plasma samples of ICU COVID-19 patients (PAI-1: 4.92 ± 0.91 vs. 1.28 ± 0.33 U/mL, p = 0.001). A positive correlation between the activity of PAI-1 and lysis time of the formed clot (r = 0.70, p = 0.0006) was observed.Conclusion Our data suggest that severe SARS-CoV-2 infection is associated with impaired fibrinolytic activity in blood, where fibrinolytic inhibitors are elevated leading to an increased resistance to clot lysis. Thromboelastography could offer a tool to investigate the contribution of the fibrinolytic status to the procoagulatory condition in COVID-19.

Introduction Inherited bleeding disorders vary in prevalence due to genetic disparity and ethnicity. Little is known about the prevalence of coagulation factor deficiency and bleeding disorders in middle-eastern population. Methods Young Saudi adults with at least one positive bleeding symptom reported in semi-structured validated condensed MCMDM-1vWD questionnaire were tested for complete blood count, routine and special coagulation tests, serum ferritin level, and capillary zone electrophoresis. After initial testing, those with prolonged prothrombin time (PT) or activated prothrombin time (APTT) had further testing to evaluate coagulation factors level. Platelet function was tested through platelet function analyzer (PFA)-100, and multiplate aggregometer (MEA) on patients suspected of having platelet disorders. Results Six-hundred-forty patients (male = 347, 54.2%) were included. A possible platelet function defect was diagnosed in three patients with one matching Glanzmann's thrombasthenia trait pattern, and one that of Bernard-Soulier trait pattern. One patient was diagnosed with von Willebrand disease. Deficiencies in coagulation factor levels were revealed as F-VIII in 14 (7.4%), F-IX in 15 (7.6%), F-II in two (3.3%), F-V in 17 (26.1%), FVII in two (3.1%), and F-X in one (1.8%) of study subjects; low vWF activity ( Conclusion The current study reports a higher prevalence of coagulation factors deficiency in Saudi population than reported in the western population.

Hemorrhage after trauma remains a significant cause of preventable death. Trauma-induced coagulopathy (TIC) at the time of hospital admission is associated with an impaired outcome. Rather than a universal phenotype, TIC represents a complex hemostatic disorder, and standard coagulation tests are not designed to adequately reflect the complexity of TIC. Viscoelastic testing (VET) has gained increasing interest for the characterization of TIC because it provides a more comprehensive depiction of the coagulation process. Thus, VET has been established as a point-of-care-available hemostatic monitoring tool in many trauma centers. Damage-control resuscitation and early administration of tranexamic acid provide the basis for treating TIC. To improve survival, ratio-driven massive transfusion protocols favoring early and high-dose plasma transfusion have been implemented in many trauma centers around the world. Although plasma contains all coagulation factors and inhibitors, only high-volume plasma transfusion allows for adequate substitution of lacking coagulation proteins. However, high-volume plasma transfusion has been associated with several relevant risks. In some European trauma facilities, a more individualized hemostatic therapy concept has been implemented. The hemostatic profile of the bleeding patient is evaluated by VET. Subsequently, goal-directed hemostatic therapy is primarily based on coagulation factor concentrates such as fibrinogen concentrate or prothrombin complex concentrate. However, a clear difference in survival benefit between these two treatment strategies has not yet been shown. This concise review aims to summarize current evidence for different diagnostic and therapeutic strategies in patients with TIC.Nach wie vor sind Blutungen die Ursache eines relevanten Anteils potentiell behandelbarer Todesfälle bei TraumapatientInnen. Das Auftreten einer trauma-induzierten Koagulopathie (TIC) bei Aufnahme ist mit einem schlechteren Outcome dieser PatientInnen assoziiert. TIC stellt eine komplexe Störung des Gerinnungssystems dar und wird durch Standardgerinnungstests nicht adäquat abgebildet. Aufgrund der umfassenderen Darstellung des Gerinnungsprozesses haben viskoelastische Tests (VET) an Bedeutung in der Charakterisierung von TIC gewonnen. VET werden daher zunehmend als bettseitig verfügbare gerinnungsspezifische Monitoringmöglichkeit verwendet. Die sogenannte “Damage-Control Resuscitation” sowie die frühzeitige Gabe von Tranexamsäure stellen die Basis der Behandlung von PatientInnen mit TIC dar. In der Hoffnung auf einen Überlebensvorteil haben viele Traumazentren weltweit Massivtransfusionsprotokolle eingeführt, welche eine frühzeitige und hochdosierte Transfusion von Plasma vorsehen. Plasma enthält alle Gerinnungsfaktoren sowie Gerinnungsinhibitoren; ein adäquater Ersatz der fehlenden Gerinnungsfaktoren bei blutenden PatientInnen kann jedoch nur durch Transfusion großer Volumina erreicht werden. Allerdings wurden für die Gabe großer Mengen an Plasmen relevante Risiken beschrieben. In einigen europäischen Traumazentren wird in diesem Zusammenhang zunehmend ein individualisiertes hämostatisches Therapiekonzept zur Behandlung von TraumapatientInnen verfolgt. Hierbei wird das individuelle, tatsächlich vorliegende Gerinnungsprofil der PatientInnen anhand von VET dargestellt. Die nachfolgende zielgerichtete Therapie basiert hauptsächlich auf der Gabe von Gerinnungsfaktorkonzentraten wie Fibrinogen oder Prothrombinkomplexkonzentrat. Ein klarer Vorteil in Bezug auf das Überleben der PatientInnen konnte jedoch bis jetzt für keine der beiden Therapiestrategien nachgewiesen werden. Das Ziel dieses Reviewartikel ist es, die aktuell verfügbare Literatur für unterschiedliche diagnostische und therapeutische Vorgehen bei PatientInnen mit TIC zusammenzufassen.

Background There are acute settings where assessing the anticoagulant effect of direct oral anticoagulants (DOACs) can be useful. Due to variability among routine coagulation tests, there is an unmet need for an assay that detects DOAC effects within minutes in the laboratory or at the point of care. Methods We developed a novel dielectric microsensor, termed ClotChip, and previously showed that the time to reach peak permittivity (T peak) is a sensitive parameter of coagulation function. We conducted a prospective, single-center, pilot study to determine its clinical utility at detecting DOAC anticoagulant effects in whole blood. Results We accrued 154 individuals: 50 healthy volunteers, 49 rivaroxaban patients, 47 apixaban, and 8 dabigatran patients. Blood samples underwent ClotChip measurements and plasma coagulation tests. Control mean T peak was 428 seconds (95% confidence interval [CI]: 401–455 seconds). For rivaroxaban, mean T peak was 592 seconds (95% CI: 550–634 seconds). A receiver operating characteristic curve showed that the area under the curve (AUC) predicting rivaroxaban using T peak was 0.83 (95% CI: 0.75–0.91, p Conclusion This diagnostic study using samples from “real-world” DOAC patients supports that ClotChip exhibits high sensitivity at detecting DOAC anticoagulant effects in a disposable portable platform, using a miniscule amount of whole blood (

Hemostasis is a complex process in which abnormalities can cause shifts toward prothrombotic or prohemorrhagic states resulting in thrombosis or bleeding, respectively. Several coagulation tests may be required to characterize these defects but may yet not always reflect a patient's true hemostatic capacity. Thus, global coagulation tests aiming to simulate the coagulation process in vitro instead of measuring single components thereof are certainly of interest to assess prothrombotic or prohemorrhagic tendencies. This review describes the development and application of global coagulation tests, concentrating on the more widely used methods of viscoelastometry and thrombin generation. A focus is placed on conditions characterized by simultaneous changes of various components of hemostasis, such as anticoagulant therapy or hormone-induced coagulopathy, in which global coagulation tests are especially promising. If the key challenges of standardization and automation of these tests are solved, as is the case with automated thrombogram or clot waveform analysis, global coagulation assays will play an important role in the future of laboratory diagnostics of hemostasis and thrombosis.Die Hämostase ist ein komplexer Prozess, bei dem Anomalien prothrombotische oder prohämorrhagische Zustände auslösen können, die zu einer Thrombose oder Blutung führen. Die Diagnose solcher Störungen kann mehrere Labortests erforderlich machen, die dennoch nicht immer die tatsächliche Hämostasekapazität eines Patienten widerspiegeln. Daher zielen Globalteste der Gerinnung darauf ab, den Gerinnungsprozess in vitro zu simulieren, anstatt einzelne daran beteiligte Komponenten zu messen. Diese Übersichtsarbeit beschreibt Entwicklung und Einsatz dieser Globalteste, wobei sie sich auf die verbreiteten Methoden der Viskoelastometrie und Thrombingenerierung konzentriert. Im Fokus stehen Zustände mit gleichzeitigen Veränderungen verschiedener Hämostasekomponenten, etwa Antikoagulanzientherapie oder Hormon-induzierte Koagulopathie, bei denen der Einsatz von Globaltesten besonders vielversprechend ist. Falls es, wie beim

Objective The aim of this study was to determine the clinical characteristics, course of disease, and outcomes of patients admitted to our pediatric intensive care unit (PICU) for Crimean–Congo hemorrhagic fever (CCHF). Methods Data of all patients with CCHF who were admitted to PICU during a 3-year period and whose diagnosis was confirmed by serological methods or polymerase chain reaction were retrospectively reviewed. Their presenting characteristics, treatments, and outcomes were extracted from the hospital's electronic database. Disease severity scoring was performed using the severity scoring index and severity grading score system. Results The data of 22 of 123 patients with suspected CCHF who were admitted to PICU were evaluated. Among them, 68.2% were males and mean age of all patients was 13.4 ± 2.2 years. The average length of stay of 10 patients was >10 days. On average, 3.72 units of platelet suspension per patient was transfused. In the course of the disease, the highest laboratory values were reached on day 3 of admission. Conclusion Poor CCHF outcome depends on thrombocytopenia severity, prolonged coagulation tests, high-liver enzyme levels, and disseminated intravascular coagulation. Poor outcomes can be avoided by CCHF awareness and preparedness, early diagnosis of the disease, and supportive treatment with appropriate fluid and blood product transfusion. Randomized controlled trials on prophylactic transfusion and ribavirin use are needed.

This article explores the application of viscoelastic tests (VETs) in trauma-induced coagulopathy and trauma resuscitation. We describe the advantages of VETs over conventional coagulation tests in the trauma setting and refer to previous disciplines in which VET use has reduced blood product utilization, guided prohemostatic agents, and improved clinical outcomes such as the mortality of critically bleeding patients. We describe different VETs and provide guidance for blood component therapy and prohemostatic therapy based on specific VET parameters. Because the two most commonly used VET systems, rotational thromboelastometry and thromboelastography, use different activators and have different terminologies, this practical narrative review will directly compare and contrast these two VETs to help the clinician easily interpret either and use the interpretation to determine hemostatic integrity in the bleeding trauma patient. Finally, we anticipate the future of new viscoelastic technologies that can be used in this setting.

Laboratory diagnostics in children and adolescents, especially in newborns and very small children, differ considerably compared with laboratory diagnostics in adults. This applies to all individual steps of the examination (i.e., the indication, the preanalytical phase, the analysis itself, and interpretation of the findings). This is particularly true in the diagnostics of hemostasis, in which small sample volumes and relatively error prone coagulation tests are posing particular challenges to the strategy, performance, and evaluation of the tests. Differences in the individual steps are illustrated below.Labordiagnostik im Kindes - und Jugendalter, vor allem bei Neugeborenen und Säuglingen unterscheidet sich erheblich von Untersuchungen bei Erwachsenen. Dies betrifft alle Schritte der Untersuchung (Indikation, präanalytische Phase, Analyse und Befundinterpretation). Bei der Gerinnungsdiagnostik ist dies besonders deutlich, da die geringe zur Verfügung stehende Probenmenge und die Störempfindlichkeit der Testsysteme hier besondere Herausforderungen an die Planung, Durchführung und Bewertung der Tests stellen. Die Besonderheiten und Unterschiede sollen hier dargestellt werden.

Many preanalytical variables may affect the results of routine coagulation assays. While advances in laboratory instrumentation have partially addressed the laboratory's ability to recognize some of these variables, there remains an increased reliance on laboratory personnel to recognize the three potential areas where coagulation testing preanalytical issues may arise: (1) specimen collection (including patient selection), (2) specimen transportation and stability, and (3) specimen processing and storage. The purpose of this article is to identify the preanalytical variables associated with coagulation-related testing and provide laboratory practice recommendations in an effort to improve the quality of coagulation testing and accuracy of result reporting.

Coagulation factor (F) V is a glycoprotein that plays an essential role in the formation of the prothrombinase complex, which is critical for progressing clot formation. FV deficiency is a rare bleeding disorder with an estimated incidence of one per 1 million in the general population. The disorder is manifested with a wide array of clinical bleeding events. The most common bleeding features of FV deficiency are mucosal bleedings. Life-threatening manifestations are rarely seen in this disorder. FV deficiency is diagnosed using routine coagulation tests and FV activity assay. A wide spectrum of mutations including missense, nonsense, and frameshift is observed throughout the F5 gene. Although fresh frozen plasma is the dominant therapeutic choice, a newly introduced plasma-derived FV concentrate was found effective in in vitro correction of prothrombin time, activated partial thromboplastin time, and thrombin generation parameters in severe FV deficiency and should provide more targeted treatment for patients with FV deficiency in the future.

The relationship between malignancy and coagulopathy is one that is well documented yet incompletely understood. Clinicians have attempted to quantify the hypercoagulable state produced in various malignancies using common coagulation tests such as prothrombin time, activated partial thromboplastin time, and platelet count; however, due to these tests' focus on individual aspects of coagulation during one specific time point, they have failed to provide clinicians the complete picture of malignancy-associated coagulopathy (MAC). Viscoelastic tests (VETs), such as thromboelastography (TEG) and rotational thromboelastometry (ROTEM), are whole blood analyses that have the advantage of providing information related to the cumulative effects of plasma clotting factors, platelets, leukocytes, and red cells during all stages of the coagulation and fibrinolytic processes. VETs have gained popularity in the care of trauma patients to objectively measure trauma-induced coagulopathy (TIC), but the utility of VETs remains yet unrealized in many other medical specialties. The authors discuss the similarities and differences between TIC and MAC, and propose a mechanism for the hypercoagulable state of MAC that revolves around the thrombomodulin–thrombin complex as it switches between activating the protein C anticoagulation pathway or the thrombin activatable fibrinolysis inhibitor coagulation pathway. Additionally, they review the current literature on the use of TEG and ROTEM in patients with various malignancies. Although limited research is currently available, early results demonstrate the utility of both TEG and ROTEM in the prediction of hypercoagulable states and thromboembolic complications in oncologic patients.

Background The anti-phospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy morbidity with persistent presence of anti-phospholipid antibodies (aPL). Laboratory criteria include aPL detection by coagulation tests for lupus anticoagulant (LAC) or solid phase assays measuring anti-β2 glycoprotein I (aβ2GPI) or anti-cardiolipin (aCL) immunoglobulin (Ig) G/IgM antibodies. External quality control programs illustrate that commercially available aPL assays produce variable results. Objective We aimed to investigate the agreement and diagnostic accuracy of solid phase assays. Materials and Methods In this multi-centre study, 1,168 patient samples were tested on one site for aCL and aβ2GPI IgG/IgM antibodies by four solid phase test systems. Samples included APS patients, controls and monoclonal antibodies (MoAB) against different epitopes of β2GPI. LAC was determined by the local centre. Results aCL IgM assays resulted in the most discrepancies (60%), while aCL IgG and aβ2GPI IgM assays resulted in lower discrepancies (36%), suggesting better agreement. Discrepant samples displayed lower median aPL titers. Dependent on the solid phase test system, odds ratios (ORs) for thrombosis and pregnancy morbidity ranged from 1.98 to 2.56 and 3.42 to 4.78, respectively. Three platforms showed lower sensitivity for MoAB directed against the glycine (Gly) 40-arginine (Arg) 43 epitope of domain I of β2GPI. Conclusion Poor agreement was observed between different commercially available aCL and aβ2GPI IgG/IgM assays, hampering uniformity in the identification of aPL-positive patients. Clinical association was globally concordant between solid phase test systems considering results of the four aPL together. An assay sensitive in detecting the MoAB against Gly40-Arg43 of domain I of β2GPI reached the highest OR for thrombosis.

The direct oral anticoagulants (DOACs) currently require no monitoring for routine therapy of atrial fibrillation or venous thromboembolism. Measurement of activity, however, may be important in patients with major and life-threatening bleeding, patients needing emergent surgery, in reversal situations, or in patients at high risk of bleeding or thrombosis due to underlying conditions. For these patients, a widely available and rapid turnaround assay would be optimal. To date, there is no such assay available, especially for the direct factor Xa inhibitors. This report describes the performance of a new, rapid turnaround, point-of-care (PoC) assay for measuring the activity of a range of anticoagulants, including DOACs and heparins, in emergency situations and for routine measurement in high-risk patients. Perosphere Technologies' PoC coagulometer is a handheld instrument that performs individual coagulation tests on samples of fresh whole blood (∼10 µL) with clotting activated by glass contact and endpoint determination performed by infrared spectroscopy. In preclinical studies using rats anticoagulated with therapeutic doses of edoxaban or enoxaparin, the PoC coagulometer showed a strong linear correlation between pharmacokinetic parameters and clotting time with edoxaban (r 2 = 0.994) and with enoxaparin (r 2 = 0.967). These preclinical results suggest that this PoC coagulometer would be ideal to assess the pharmacodynamic effects of anticoagulants and their reversal agents. The PoC bedside instrument delivers results within minutes and requires no more than a drop of whole blood. Studies are underway to confirm these results in humans and to further characterize the performance of the instrument.

Background Patients with cyanotic congenital heart disease (CCHD) have multifactorial hematologic abnormalities. In continuation of our previous study titled “Coagulopathies in Cyanotic Cardiac Patients: An Analysis with Three Point-of-Care Testing Devices (Thromboelastography, Rotational Thromboelastometry, and Sonoclot Analyzer),” we extended this prospective observational study to a larger cohort to reconfirmed the need to do a point-of-care (POC) test in bleeding cyanotic children. We formulated an algorithm. We conducted this study now by comparing three different POC parameters in an algorithm-based manner and deciphering the best parameter from an algorithm-based and the best parameter POC from an algorithm-based perspective. We conducted this study to compare three different viscoelastic POC tests: thromboelastography (TEG), rotational thromboelastometry (ROTEM), and Sonoclot analyzer to predict thrombocytopenia and hypofibrinogenemia in cyanotic cardiac surgery patients. Material and Methods A total of 105 patients of either sex, who were scheduled to undergo elective cardiac surgery for CCHD on cardiopulmonary bypass (CPB), were enrolled after obtaining written and informed consent. Blood samples for TEG, ROTEM, Sonoclot, and standard laboratory coagulation tests were collected after induction of anesthesia (T1) and 30 minutes after protamine reversal (T2). Results We observed significant correlations between POC parameters, platelet count, and serum fibrinogen levels. Area under the curve (AUC, 0.90) of ROTEM FIBTEM-A10 was found to be superior in detecting hypofibrinogenemia (serum fibrinogen < 200 mg/dL). AUC of TEG α angle (AUC 0.79), TEG MA (AUC 0.77) and Sonoclot CR (AUC 0.73) were comparable. Sonoclot PF was found to have highest AUC (0.95) to detect thrombocytopenia (platelet count < 100,000/μL). ROTEM FIBTEM-A10 at cutoff value ≤ 7.5 mm had highest sensitivity (87.2%) and specificity (80.3%) to detect hypofibrinogenemia. Sonoclot PF at cutoff value ≤ 0.95 had highest sensitivity (100%) and specificity (83.7%) to detect thrombocytopenia. We formulated a POC algorithm based on cutoff value derived from ROC curves. Conclusion In conclusion, although all three viscoelastic POC devices (TEG, ROTEM, and Sonoclot) can be used to detect hypofibrinogenemia and thrombocytopenia, it was reaffirmed on a larger subset of patients that ROTEM FIBTEM has highest diagnostic accuracy for hypofibrinogenemia, whereas Sonoclot PF has highest diagnostic value for thrombocytopenia in CCHD surgical patients.

Disorders of the coagulation system can seriously impact the clinical course and outcome of neurosurgical patients. Due to the anatomical location of the central nervous system within the closed skull, bleeding complications can lead to devastating consequences such as an increase in intracranial pressure or enlargement of intracranial hematoma. Point-of-care (POC) devices for the testing of haemostatic parameters have been implemented in various fields of medicine. Major advantages of these devices are that results are available quickly and that analysis can be performed at the bedside, directly affecting patient management. POC devices allow identification of increased bleeding tendencies and therefore may enable an assessment of hemorrhagic risks in neurosurgical patients. Although data regarding the use of POC testing in neurosurgical patients are limited, they suggest that coagulation testing and hemostatic therapy using POC devices might have beneficial effects in this patient population. This article provides an overview of the application of point-of-care coagulation testing in clinical practice in neurosurgical patients.

Bleeding complications after cardiac surgery are common and are associated with increased morbidity and mortality. Their etiology is multifactorial, and treatment decisions are time sensitive. Point-of-care (POC) testing has an advantage over standard laboratory tests for faster turn-around times, and timely decision on coagulation intervention(s). The most common POC coagulation testing is the activated clotting time (ACT), used to monitor heparin therapy while on cardiopulmonary bypass. Viscoelastic coagulation tests including thromboelastometry (ROTEM) and thromboelastography (TEG) have been recommended for the treatment of postoperative bleeding after cardiac surgery because the ROTEM/TEG-guided treatment algorithms reduced the use of blood products. Other POC tests are commercially available, but there is sparse evidence for their routine use in cardiac surgery. These devices include heparin management systems, POC prothrombin time and activated partial thromboplastin time, POC fibrinogen assay, and whole blood platelet function tests. There are multiple confounding elements and conditions associated with cardiac surgery, which can significantly alter test results. Anemia and thrombocytopenia are regularly associated with deviations in many POC devices. In summary, POC coagulation testing allows for rapid clinical decisions in hematological interventions, and, when used in conjunction with a proper transfusion algorithm, may reduce blood product usage, and potentially complications associated with blood transfusion.

Direct oral anticoagulants (DOACs) exert similar anticoagulant effects to vitamin K antagonists and are increasingly used worldwide. Nevertheless, an evidence-based approach to patients receiving DOACs when any unplanned urgent surgery or bleeding (either spontaneous or traumatic) occurs is still missing. In this review, we investigate the role of point-of-care coagulation tests when other, more specific tests are not available. Indeed, thromboelastography and activated clotting time can detect dabigatran-induced coagulopathy, while their accuracy is limited for apixaban and rivaroxaban, mostly in cases of low drug plasma concentrations. These tests can also be used to guide the reversal of DOAC-induced coagulopathy providing a quick, before-and-after picture in case of therapeutic use of hemostatic compounds.

Direct oral anticoagulants (DOACS) are used for stroke prevention in patients with atrial fibrillation as well as for prophylaxis and treatment of venous thromboembolism. Clinicians who treat, or may encounter, patients with DOAC exposure, should be aware of the limitations of coagulation testing in this setting, and seek counsel from their laboratory to understand the effects of DOACS on coagulation results. Generally, assays that employ clot based principles, or methods that require thrombin or Factor Xa activation or substrates may be affected by the presence of DOACS. The clinical laboratory should have an algorithmic testing plan for adequately assessing the presence of all DOACS and readily provide this information to clinicians. We describe Clinical Pearls for DOAC assessment using common and esoteric coagulation testing. Direkte orale Antikoagulanzien (DOAK) werden zur Schlaganfallprophylaxe bei Patienten mit Vorhofflimmern und zur Prophylaxe sowie Behandlung von venosen Thrombembolien eingesetzt. Arzte, die Patienten unter DOAK-Therapie behandeln oder mit diesen konfrontiert werden, sollten sich uber die Grenzen der Bestimmung der Gerinnungswerte unter diesen Bedingungen im Klaren sein. Sie sollten den Rat ihres Labors einholen, um die Wirkungen der DOAK auf die Gerinnungswerte richtig einzuschatzen. Generell konnen Assays, die auf funktionellen Clotting-Tests basieren, oder Methoden, die Thrombin oder Faktor Xa als Substrat verwenden bzw. deren Aktivierung erfordern, von DOAK beeinflusst werden. Das klinische Labor sollte uber einen algorithmischen Testplan verfugen, um die Prasenz aller DOAK in geeigneter Weise zu beurteilen und den Arzten diese Informationen umgehend zur Verfugung stellen zu konnen. Wir beschreiben klinische Perlen fur die DOAK-Untersuchung anhand der ublichen Gerinnungstests wie auch selteneren Verfahren. Nachdruck aus und zu zitieren als: Hamostaseologie 2017; 37: 295–301

SummaryPatients with type 3 von Willebrand disease (VWD-3) have no measurable levels of VW factor (VWF) and usually require treatment with VWF-FVIII concentrate to prevent and/or stop bleeding. Even though the patients are treated prophylactically, they may experience bleeding symptoms. The aim of this study was to evaluate the effect of VWF-FVIII concentrate treatment in VWD-3 patients with the Total Thrombus Analysis System (T-TAS®), which measures thrombus formation under flow conditions. Coagulation profiles of 10 VWD-3 patients were analysed using T-TAS before and 30 minutes after VWF-FVIII concentrate (Haemate®) injection. Results were compared to VWF- and FVIII activity in plasma, and results with thromboelastometry and ris-tocetin-activated platelet impedance aggregometry (Multiplate®) in whole blood. For comparison, 10 healthy controls were also analysed with T-TAS. A median dose of 27 (range 15–35) IU/kg of VWF-FVIII concentrate increased VWF- and FVIII activity as expected. T-TAS thrombus formation was enhanced when a tissue factor/collagen-coated flow chamber was used at low shear, but treatment effects at high shear using a collagen-coated flow chamber were minimal. Whole blood coagulation assessed by thromboelastometry was normal and did not change (p > 0.05) but ristocetin-induced platelet aggregation improved (p < 0.001). In conclusion, T-TAS detects effects of VWF-FVIII concentrate treatment on coagulation-dependent thrombus formation at low shear, but minor effects are observed on platelet-dependent thrombus formation at high shear. The poor prediction of bleeding by conventional laboratory monitoring in VWD-3 patients might be related to insufficient restoration of platelet-dependent thrombus formation.

Einleitung Im Jahr 2006 wurde eine interdisziplinare Stellungnahme zur praoperativen Gerinnungsdiagnostik bei Kindern vor einer Tonsillektomie/Adenotomie (TE/AT) veroffentlicht. Diese empfiehlt, auf die praoperative „Routinegerinnung“ zu verzichten und stattdessen einen standardisierten Fragebogen zur Abklarung einer Blutungsneigung zu verwenden. Ziel der vorliegenden Studie war es zu uberprufen, ob es nach der Umsetzung der Empfehlung zu einer Veranderung der Nachblutungsrate gekommen ist. Methoden Mittels einer retrospektiven Datenanalyse der Jahre 2003 und 2009 wurde die Inzidenz von Nachblutungen bei Kindern nach TE, AT und kombinierter ATE untersucht. Wahrend 2003 nur eine freie Anamnese durchgefuhrt wurde und in Teilen eine Routinegerinnung vorlag, wurden 2009 alle Kinder durch den standardisierten Fragebogen gescreent und im Verdachtsfall eine umfassende Gerinnungsdiagnostik vorgenommen. Ergebnisse 2003 wurden 352 Kinder operiert, in 25 Fallen (7,1%) kam es zu Nachblutungen, wovon 18 (6,1%) revidiert werden mussten. 2009 wurden 293 Kinder operiert, 20 (6,8%) Kinder erlitten eine Nachblutung, 14 (4,7%) wurden operativ revidiert. Ein statistisch signifikanter Unterschied in der Nachblutungsrate zwischen beiden Kollektiven zeigte sich nicht. Bei 5 der Kinder, die 2003 nachgeblutet hatten, lag praoperativ ein Gerinnungslabor vor, das in allen Fallen unauffallig war. Auch alle postoperativ durchgefuhrten Gerinnungsuntersuchungen, die im Anschluss an die Nachblutungen in beiden Gruppen durchgefuhrt wurden, waren unauffallig. Schlussfolgerung Die Anwendung des standardisierten Fragebogens unter Verzicht auf eine Routinegerinnung fuhrt nicht zu einer nachweisbaren Veranderung der Nachblutungsrate nach TE/AT. Die Ergebnisse bestatigen daruber hinaus, dass Nachblutungen nach TE/AT in aller Regel nicht Ausdruck einer kompromittierten Blutgerinnung sind.

A previously healthy 3-year-old girl presented with a short history of mucocutaneous bleeding and a spontaneous left knee hemarthrosis following a nonspecific viral gastroenteritis. Initial investigations for a bleeding disorder revealed a normal platelet count; however, coagulation studies revealed a prothrombin time (PT) of 25 seconds and an activated partial thromboplastin time (APTT) of 66 seconds (both prolonged). The APTT did not correct on mixing with normal plasma, and further testing confirmed the presence of a strong lupus anticoagulant (LA). One-stage assays of factor VIII, VII, and X were normal, but factor II was markedly reduced. Based on this distinct clinicopathological picture, a diagnosis of lupus anticoagulant hypoprothrombinemia syndrome (LAHS) was made. Due to the presence of a hemarthrosis, the patient was treated with clotting factor concentrate. Human prothrombin complex concentrate (PROTHROMBINEX-VF) was used as a source of factor II replacement; however, during the infusion the patient developed anaphylaxis necessitating resuscitation. The patient was observed without further factor replacement, and the bleeding symptoms resolved over several days. Within 3 weeks her PT and factor II had normalized but the APTT remained prolonged. After 6 months the coagulation profile had completely normalized and the LA was negative. It is unusual to require replacement of factor II in paediatric LAHS because bleeding is typically minor and self-limited. Anaphylaxis to clotting factor concentrates has not been previously reported in the context of LAHS, but is well described in patients with congenital factor IX deficiency (hemophilia B). Whilst the potential mechanism for anaphylaxis in our patient is unknown, it is recommended that human prothrombin complex concentrates should be used cautiously in paediatric LAHS.

Glanzmann thrombasthenia is a rare inherited coagulation disorder, manifesting itself in early childhood as bleeding episodes. The patients with this disease may present with uncontrollable bleeding following trauma. We report a patient of Glanzmann syndrome with head injury, who presented to us following fall from stairs. Platelet transfusion is the mainstay of treatment in emergency situations. As patients generally have a history of platelet transfusion they may be refractory to the same. Leuko reduced or human leukocyte antigen matched platelets should be used. Recombinant factor VIIa can be used to control bleeding in refractory cases and in patients with antibodies against platelets. Anti-fibrinolytics can also be used as adjuvants. There is need of advanced perioperative coagulation screening spot tests in emergency trauma settings as routine coagulation tests may not be able to pick up the abnormality. Thromboelastography/thromboelastometry can be a great tool for perioperative management of such coagulation disorders.

The perioperative management of dabigatran is challenging, and recommendations based on activated partial thromboplastin time (aPTT) and thrombin time (TT) are unsatisfactory. Dedicated coagulation tests have limitations at plasma concentrations < 50 ng/ml. Therefore, a more sensitive test, which is available 24/7, is required. It was the aim of this study to investigate the performance of the Hemoclot Thrombin Inhibitors® LOW (HTI LOW) kit, a diluted thrombin time, and the STA® – ECA II (ECA-II) kit, a chromogenic variant of the ecarin clotting time, that were developed to measure low dabigatran concentrations, compared to reference dabigatran analysis by liquid chromatography tandem mass-spectrometry (LC-MS/MS). This study included 33 plasma samples from patients treated with dabigatran etexilate who had plasma concentrations < 200 ng/ml. HTI LOW and ECA-II were performed along with HTI, aPTT (STA®-C. K.Prest® and SynthasIL ®) and TT (STA® – Thrombin). All procedures were performed according to recommendations by the manufacturers. Linear (or curvilinear) correlations and Bland-Altman analyses were calculated. For free dabigatran concentrations < 50 ng/ml, the R2 of linear correlations were 0.69, 0.84 and 0.61, with HTI, HTI LOW and ECA-II, respectively. The R2 for TT, STA®-C. K.Prest® and SynthasIL® were 0.67, 0.42 and 0.15. For HTI, HTI LOW and ECA-II, Bland-Altman analyses revealed mean differences of –6 ng/ml (95 %CI: –25–14 ng/ml), 1 ng/ml (95 %CI: –18–19 ng/ml) and –1 ng/ml (95 %CI: –25–23 ng/ml), demonstrating that tests dedicated to measuring low concentrations are more accurate than HTI. In conclusion, the use of HTI LOW or ECA-II to assess low plasma dabigatran concentrations is supported by our findings.

Cirrhosis presents with decreased procoagulant factors as a consequence of the impaired synthetic capacity of the liver. This was taken as evidence to explain the abnormalities of the coagulation tests prothrombin time (PT) and activated partial thromboplastin time (aPTT) and the bleeding events that occur in these patients. It was for long time (and probably is still) common practice to test patients with the PT and to treat those with predefined (but arbitrary) cutoff values with plasma or prohemostatic agents to prevent or stop bleeding. However, anticoagulant factors that contrast the procoagulants are also decreased in cirrhosis. It was therefore postulated that the coagulation balance (i.e., the net result between the action of pro- and anticoagulants) is somewhat rebalanced. Subsequent studies supported this view showing that plasma from cirrhotic patients generates normal amounts of thrombin. In addition, primary hemostasis (i.e., platelet-vessel wall interaction) is rebalanced notwithstanding cirrhosis present with thrombocytopenia. It was shown that increased levels of the adhesive protein von Willebrand factor (a typical feature of cirrhosis) compensate for the low number (function) of platelets. The earlier considerations have been instrumental to help dismantle the old paradigms of cirrhosis as the epitome of the acquired hemorrhagic coagulopathies and the traditional coagulation tests PT and aPTT as suitable predictors of bleeding risk. The demise of the old paradigms and the rise of the new one may have important practical implications for the management of patients with cirrhosis and will be discussed in this chapter.

Cardiac surgery with cardiopulmonary bypass determines a serious imbalance of the hemostatic system. The clinical pattern is multifactorial, involving patient-related, drug-related, and surgery-related factors. As a result, the patient is prone to both hemorrhagic and thrombotic complications. To address the clinical management of a bleeding patient after cardiac surgery, avoiding empirical administration of drugs and blood derivates, it is mandatory to correctly identify the factor(s) responsible for bleeding. Bleeding after cardiac operations can be ascribed to seven basic mechanisms: residual heparin effect; reduced thrombin generation; fibrinogen deficiency; thrombocytopenia; platelet dysfunction; hyperfibrinolysis; and surgical sources. These factors may interact together, creating a complex coagulopathy. Point-of-care coagulation tests are useful to orienteer the clinician in this complex scenario. Viscoelastic coagulation tests find their greater usefulness in the diagnosis of the bleeding mechanism(s), whereas platelet function tests appear more useful for the preoperative assessment of patients under the effects of antiplatelet agents. Thromboembolic complications are the other side of the coin, and their prevention is still a matter of debate. Consumption of natural anticoagulants and endothelial disturbance are important mechanisms underlying this condition. Strategies to limit antithrombin (AT) consumption or to correct low postoperative levels of AT are still a matter of discussion.

Defensive medicine is a term conventionally used for defining the medical (mal)practice of ordering medically questionable diagnostic testing, procedures, or visits, or to avoid high-risk patients or procedures. The practice of defensive medicine may primarily be aimed to reduce exposure to malpractice liability, to avoid patient criticism regarding "medical inaction," or to avoid "missing" some otherwise potential identifiable defect(s). Although the precise impact of defensive medicine in the field of laboratory testing is difficult to estimate from the current literature, the overuse or inappropriate use of laboratory resources ranges from 23 to 67%, and a large part of this can be attributed to medical liability concerns, with apparently little clinical awareness of the adverse consequences that may be associated with this practice. Essentially, performing inappropriate testing remarkably increases the risk of obtaining false-positive results due to statistical, preanalytical, and analytical reasons, thus triggering further and potentially even more invasive follow-up testing, inappropriate patient management, along with incremental increases of expenditure due to misuse of health care resources. As routine coagulation testing is commonly performed for the screening of patients with bleeding or thrombotic disorders, either a false-negative or a false-positive result may significantly impact on clinical outcomes and health care resources. The aim of this article is to describe the leading causes of physiological, pathological, therapeutic, and spurious variations of the prothrombin time, activated partial thromboplastin time, and D-dimer, as well as the potential clinical consequences emerging from the generation of false-negative and false-positive results with these tests.

The clinical hemostasis laboratory is a complex testing arena which employs numerous coagulation assays and spans several different test methodologies. Adding further complexity, these test results are expressed in a wide variety of unique units (concentration, activity, time, percentage, and ratio). Unfortunately, many of these reference values are derived from a local plasma pool or manufacturer's standards, as there are few established international standards. These three main issues complicate the validation and performance of the coagulation testing. Before an assay can be introduced into clinical use, both analytical and clinical performance parameters must be validated or verified using the standard validation procedures of the laboratory. This article summarizes the initial evaluation and validation processes of the coagulation laboratory, which sometimes can be difficult concepts to implement. A standardized validation protocol is described in this article and, if used, will help to objectively evaluate the assay performance and determine if it meets acceptable laboratory criteria.

SummaryWhile laboratory monitoring is not required in patients treated with apixaban, a direct factor-Xa inhibitor, assessment of its concentration is useful in some critical situations. However, few data are available on its effect on coagulation tests and on the suitability of anti-Xa assays for its quantification. It was the objective of this study to identify laboratory tests suitable for apixaban concentration assessment. Coagulation tests – PT and aPTT- and anti-Xa assays were performed in apixaban-spiked plasma samples. To evaluate the sensitivity of PT and aPTT to apixaban, we conducted a first monocenter part, with a wide range of concentrations (50–1,000 ng/ml), a large panel of reagents (20 reagents), and two coagulometers (STAR®, Stago and ACL TOP®, IL), and a second multicenter part involving 13 laboratories using either a common PT reagent (RecombiPlastin2G®) or the local PT and aPTT reagents. In the multicentre part, five blinded apixaban-spiked plasma samples (0/100/200/400/800 ng/ml – checked by HPLC-MS/MS) were used; apixaban concentrations were measured with three anti-Xa assays, apixaban calibrators and controls (Stago). PT and aPTT tests using a large panel of reagents displayed a low sensitivity to a wide range of apixaban concentrations. The concentrations to double PT ranged from 400 to >1,000 ng/ml with the 10 reagents. With the three anti-Xa assays, interlaboratory precision and accuracy were below 11% and 12%, respectively. In conclusion, whereas PT and aPTT tests were not sensitive enough to detect apixaban, the three anti-Xa assays tested using lyophilised apixaban calibrators and controls allowed to reliably quantify a wide range of apixaban concentrations.

Because their anticoagulant effect is dose predictable, steady, and little influenced by diet and drugs, laboratory monitoring was deemed unnecessary in trials on venous and arterial thromboprophylaxis with the direct oral anticoagulant drugs (DOACs) rivaroxaban, apixaban, edoxaban, or dabigatran. However, there are special clinical settings in which measurement of their anticoagulant effect may be clinically desired. Because of lack of standardization between reagents employed and their global nature, the activated partial thromboplastin time (APTT) and the prothrombin time (PT) are not generally suitable for accurately assessing the anticoagulant effect of DOACs. The modified (diluted) PT reliably quantifies the anticoagulant effect of rivaroxaban or of apixaban. However, a higher intraindividual variability from one PT reagent to another is found when the data are compared with those obtained with standard PT. The HEMOCLOT (HYPHEN BioMed, France) assay is a modified (diluted) thrombin time (TT) provided with dabigatran calibrators. However, it is performed only in few specialized centers. Anti-factor Xa (anti-FXa) chromogenic assays employ routine automated coagulometers or manual spectrometers, and kits for anti-FIIa assays that measure dabigatran levels and kits for anti-Xa with rivaroxaban calibrators are commercially available. However, no correlation has been identified between any of these tests and clinical outcomes in patients taking any of the DOACs. Thus, currently, there are evidence gaps regarding the role of laboratory testing for surveillance and management of adverse events associated with DOACs. In view of this, in addition to standardization, validation of such assays is mandatory before they can be used to make clinical decisions.

The use of frozen-thawed samples rather than fresh samples for specialized coagulation testing is becoming commonplace, thereby creating novel risks that may jeopardize the quality of hemostasis testing. Residual platelets (PLTs) in frozen plasma are most critical as freezing-induced activation and injury may impair routine and specialized testing after thawing. The aim of this study was to verify the impact of postcentrifugation PLT count in postfreeze-thawed samples on activated partial thromboplastin time (APTT), prothrombin time (PT), fibrinogen, factor VIII (FVIII) activity testing, and factor IX (FIX) activity testing. These parameters were herein assessed in postfreeze-thaw paired plasma samples collected from 15 healthy volunteers and subjected to 4 different centrifugation forces (i.e., 3,000, 1,500, 1,000, and 500g), using data obtained with centrifugation force of 1,500g as the gold standard, in agreement with current recommendations. Compared with reference samples, PLT counts in fresh aliquots were indistinguishable in specimens centrifuged at 1,000g, significantly lower in those centrifuged at 3,000g and significantly higher in those centrifuged at 500g. In all cases except samples centrifuged at 3,000g, the PLT count was significantly decreased in postfreeze-thaw compared with paired fresh specimens. In postfreeze-thaw plasma, APTT was not influenced by residual PLT count. The results of PT and fibrinogen were consistently altered in samples centrifuged at 1,000 and 500g, though the correlation with the reference measures remained clinically acceptable. Data obtained for FVIII and FIX activities revealed a positive bias in all postfreeze-thaw plasmas, achieving statistical significance in samples centrifuged at 3,000g. We conclude that alteration of centrifuge speeds away from the recommended 1,500g may influence the level of residual PLTs in sample centrifuged at lower speeds such as 500g, and therefore may make these specimens unsuitable for hemostasis testing in postfreeze-thawed plasma samples. In addition, although the changes seen in FVIII and FIX in samples centrifuged at 3,000g may reflect non-PLT-related effects, such changes should also be considered in this setting.

Dabigatran, ein direkter und reversibel bindender Faktor-IIa-Hemmer, ist in Europa zur Schlaganfallprophylaxe bei Vorhofflimmern und zur primaren Thromboseprophylaxe nach elektivem Huft- und Kniegelenkersatz zugelassen. Im Gegensatz zu Vitamin-K-Antagonisten ist eine routinemasige Kontrolle der gerinnungshemmenden Wirkung von Dabigatran nicht notwendig. Eine Abschatzung der antikoagulatorischen Wirkung von Dabigatran konnte fur den klinisch tatigen Arzt in spezifischen Situationen wie vor Notfalloperationen oder schweren Blutungen wichtig sein und kann durch die aktivierte partielle Thromboplastinzeit, Ecarin Clotting Time oder Thrombinzeit durchgefuhrt werden. Der spezifisch fur Dabigatran kalibrierte verdunnte Thrombinzeit Test (Hemoclot®) kann fur quantitative Aussagen zu Plasmakonzentrationen eingesetzt werden. Zur Normalisierung des Blutungsrisikos vor elektiven Eingriffen bei Patienten mit normaler Nierenfunktion reicht in der Regel ein Absetzen von Dabigatranetexilat 24 Stunden vor dem Eingriff aus. Bei eingeschrankter Nierenfunktion oder bei einem Eingriff mit erhohtem Blutungsrisiko verlangern sich die empfohlenen Absetzfristen dementsprechend. Beim Auftreten von Blutungen wahrend einer Therapie mit Dabigatran richtet sich die weiterfuhrende Behandlung nach dem Schweregrad und Lokalisation der Blutung. Eine Besonderheit besteht darin, dass Dabigatran mittels Dialyse aus dem Kreislaufsystem relativ rasch entfernt werden kann. Empfehlungen: Bei aus klinischer Sicht leichten Blutungen ist eine kurzfristige Verschiebung der Substanzeinnahme anzuraten. Der Zeitraum basiert hier auf dem individuellen Thromboserisiko des Patienten. Die Gabe von Faktorenkonzentraten ist bei leichten Blutungen nicht indiziert. Bei mittelschweren bis schweren Blutungen sollte nach Absetzen von Dabigatran insbesondere auf die Stabilisierung der Herz- und Kreislauffunktion durch Volumenersatz und Blutprodukte sowie auf die (lokale) Behandlung des Blutungsherdes geachtet werden. Falls die Option besteht, kann Dabigatran mittels Haemofiltration oder Dialyse schnell und effektiv aus dem Kreislaufsystem entfernt werden. Bei schweren oder lebensbedrohlichen Blutungen wird ein spezielles Hamostasemanagement erforderlich. Je nach Lokalisation der Blutung sollte nebst der hamodynamischen Stabilisierung des Kreislaufes der Einsatz von Faktorenkonzentraten in dieser Situation zeitnah erfolgen. Wichtig ist hierbei, dass die Standard- Laborparameter den Effekt der Faktorenkonzentrate nicht akkurat wiedergeben. Daher sollte der Effekt klinisch anhand der einsetzenden Blutgerinnung beurteilt werden.

SummaryThe impact of hypoxaemia on blood coagulation remains unclear despite use of a variety of measures to address the issue. We report the first use of thromboelastography (TEG) at high altitude to describe the dynamics of clot formation in whole blood samples. Seventeen healthy volunteers ascended to 5,300 m following an identical ascent profile; TEG measurements at 4,250 m and 5,300 m were compared with those from sea level. Peripheral oxygen saturation (SpO2) and haematocrit were also measured. Ascent resulted in a decline in SpO2 from 97.8 (± 1.2) % at sea level to 86.9 (± 3.3) % at 4,250 m and 79.5 (± 5.8) % at 5,300 m (p

Compounds that are systemically absorbed during the course of cigarette smoking, and their metabolites, affect the coagulation system and cause endothelial dysfunction, dyslipidemia, and platelet activation leading to a prothrombotic state. In addition, smoking increases the activity of fibrinogen, homocysteine, and C-reactive protein. We hypothesize that smoking may affect functional coagulation testing during pregnancy. A secondary analysis of 371 women pregnant with a singleton pregnancy and enrolled in a multicenter, prospective observational study of complications of factor V Leiden mutation subsequently underwent functional coagulation testing for antithrombin III, protein C antigen and activity, and protein S antigen and activity. Smoking was assessed by self-report at time of enrollment (

Many patients scheduled for operative procedures either as outpatients or after admission to a hospital undergo routine blood counts, laboratory tests and analysis of the plasmatic coagulation system. From the scientific literature it is obvious that these kind of routine test will yield pathological results in only a few patients and will only very rarely lead to clinically relevant modifications of perioperative therapy. The preoperative evaluation of patients scheduled for surgery should therefore focus on a very thorough history and physical examination of the patient. Patient with an unremarkable history for bleeding and without any sign of clinically relevant organ dysfunction may not undergo any routine blood test at all. Pathological findings during physical examination or in the patient's history should lead to is specific laboratory tests.

Thrombin generation is a key process that determines the extent of a hemostatic plug or a thrombotic process. The ensuing thrombin burst is crucial for the formation of a stable fibrin clot. During its active life, thrombin exerts a multitude of highly regulated actions on the blood and the vessel wall, among which is the clotting of fibrinogen. The inappropriate generation of thrombin may lead to pathological processes, foremost of which are hemorrhagic or thrombotic diseases. The coagulation system is usually investigated by means of two in vitro classical clotting tests, the activated partial thromboplastin time and prothrombin time. These assays assess only the time taken to form a clot and do not entirely reflect global hemostatic balance. They permit identification of connectivity between the component activities identified as required for plasma coagulation and define the concept of intrinsic and extrinsic coagulation pathways, which converge at the step of formation of the prothrombinase complex. However, the mechanisms established by in vitro tests are not always mirrored in the human pathologies associated with bleeding or thrombosis. The recent development of newer tests based on the continuous registration of thrombin generation (TG) under in vitro conditions that mimic more closely what occurs in vivo prompted us to reinvestigate the balance between procoagulants and anticoagulants in patients. Thrombin generation assays (TGA) not only provide an overall assessment of hemostasis, but they also target potential extrahemostatic effects of the generated thrombin, a potent agonist of a multitude of cellular activation pathways. Moreover, estimation of an individual's thrombin generation potential may correlate more closely with a hyper- or hypocoagulable phenotype, compared with traditional coagulation tests. In this review, we discuss to what extent TG can be expected to reflect the clotting function of blood, the development and use of different TGA systems suitable for detecting changes in the kinetics of thrombin generation, and the test's clinical utility for patients with hemophilia or von Willebrand disease.

For preoperative haemostatic assessment a structured questionnaire for the bleeding history of the patient should be primarily used. Only in case of abnormalities an additional laboratory coagulation testing is recommended. Such a test set must include functional testing of platelets as defects of the primary haemostasis are frequent. In the event of acute acquired perioperative coagulopathy laboratory coagulation testing is a prerequisite for sophisticated and precise diagnosis and therapy. Points of care techniques like thrombelastography are capable to provide fast and extensive information.

SummaryIm Vergleich zu anderen Labortests weisen Gerinnungstests eine relativ große Fehleranfälligkeit und eine größere analytische Variabilität auf, was nicht zuletzt mit der relativ komplexen Präanalytik zusammenhängt. Daher mehrere Richtlinien erschienen, die helfen sollen, die Präanalytik in der Hämostaseologie zu standardisieren. Obwohl die publizierten Richtlinien zweifellos wertvolle Anhaltspunkte für die tägliche Laborpraxis darstellen, handelt es sich in einigen Bereichen um Maximalkriterien, die sich technisch und logistisch im diagnostischen Alltag nicht immer vollständig umsetzen lassen.In diesem Übersichtsartikel sollen häufige Problemfelder in der Präanalytik der Routine-Gerinnungstests diskutiert werden. Da die Stabilität von Gerinnungstests wie z. B. der Prothrombinzeit und der partiellen Thromboplastinzeit stark von lokalen Faktoren abhängen (z. B. Röhrchentyp, Hersteller, Reagenzien und Analysesysteme) wird empfohlen, dass jedes Labor auf Basis der Richtlinien detaillierte Verfahrensanweisungen für die Ein-sender entwickelt, um die präanalytische Variabilität zu vermindern.

SummaryThe antiphospholipid syndrome (APS) is a non-inflammatory autoimmune disease characterized by the presence of antiphospholipid antibodies (aPL) in the plasma of patients with vascular thrombosis, recurrent complications of pregnancy, or both (1, 2). The presence of aPL in plasma of patients can be detected with either a prolongation of phospholipid dependent coagulation tests (lupus anticoagulant, LAC), or with solid phase immune assays against the protein β2-glycoprotein I (β2-GPI) or the phospholipid cardiolipin (anti-β2-GPI antibody ELISA and anti-cardiolipin antibody ELISA, respectively) (3). For a long time there was a lot of confusion on who had the syndrome and who not. To solve this dispute, an international consensus meeting was organized in Sapporo in 1999 to formulate classification criteria for patients with the antiphospholipid syndrome (4). These criteria have been updated in 2004 at another international consensus meeting in Sydney (5). The classification criteria were defined for scientific purposes and were aimed to be used as inclusion criteria in patient related studies. They were specifically not defined for diagnostic purposes. However, current practice is that these criteria are used as a diagnostic tool. This is very unfortunate because the specificity of the different aPL assays to detect the clinical manifestations that characterize APS are disputable. One of the aims of defining the criteria was to initiate studies to determine the value of the different anti-phospholipid antibody assays to serve as biomarker for the risk of thrombosis and pregnancy morbidity. The recent progress made on this important topic will be discussed.

Thrombin plays an important role in hemostasis through its multiple functions across blood coagulation, platelet activation, and fibrinolysis. The measurement of thrombin generation is therefore viewed as a potentially useful test that could be applied to the screening, monitoring, and/or diagnosis of hemostatic abnormalities. Indeed, advances in thrombin generation assays have created significant interest and debate as to whether they may provide a more physiologically relevant testing system than do traditional coagulation tests. A variety of thrombin generation assays, including commercially available systems, have been investigated for their correlation with hypocoagulable and hypercoagulable states. Although there is an extensive body of literature that has investigated the application of thrombin generation assays, some limitations remain. These include poor standardization of reagents and methods and a lack of large prospective studies that demonstrate clear relationships between thrombin generation with bleeding and thrombosis phenotypes, as well as with monitoring anticoagulation. Whether thrombin generation assays become more "useful" than "hype" will require well-designed, large, prospective multicenter trials using standardized methods.

SummaryWe analysed changes in coagulation during normal pregnancy with a novel point-of-care device based on thrombelastometry (ROTEM®). We compared the results obtained with those of standard coagulation tests in 104 patients: 20 non-pregnant women (controls) and 84 women in the first (T1, n=17), second (T2, n=9) and third (T3, n=58) trimesters of pregnancy. We measured the clotting time (CT), the maximum clot firmness (MCF), the early clot amplitude at 5 and 15 minutes (CA5, CA15) and the clot lysis index (CLI30) with four tests containing specific reagents. (a) The INTEM® test involving ellagic acid activated the intrinsic pathway and (b) the EXTEM® test using tissue factor triggered the extrinsic pathway; (c) The FIBTEM® test based on a platelet inhibitor (cytochalasin D) evaluated the contribution of fibrinogen to clot formation and (d) the APTEM® test was similar to the EXTEM but was based on inhibition in vitro of fibrinolysis by aprotinin. CT and CLI30 were not significantly modified during pregnancy whereas MCF, CA5 and CA15 (INTEM, EXTEM, FIBTEM) increased significantly between the second and third trimesters (e.g. median [interquartile range]: MCF-FIBTEM, 13 [11–16] mm vs. 19 [17–23] mm, respectively, in controls and T3, p< 0.001). EXTEM values were not significantly different from those measured with APTEM. There were significant correlations between the results obtained with ROTEM and those from standard coagulation tests. ROTEM analysis showed a marked increase in coagulability during normal pregnancy. ROTEM values may serve as the basis for future studies in pregnant women.

BACKGROUND Operations in children are often drastic events for patients and their parents. Most ENT operations are elective. Often blood tests are done even though there is no clinical evidence for coagulation disorders or anaemia in the medical history of the patient and their family. Since the joint statement of the German Societies of Oto-Rhino-Laryngology, Head and Neck surgery, of pediatrics and of anesthesiology regarding the necessity of coagulation tests prior to adenoidectomy or tonsillectomy in children we wanted to know whether blood tests have any effect for ear operations. METHODS AND PATIENTS Data of 81 children were analysed, undergoing an ear operation during 2006/2007 at the department of Oto-Rhino-Laryngology in Bochum, retrospectively. Information on sex, age, hemoglobin concentration, platelet count, INR, thromboplastin time, prothrombin time, count of the white blood cells, Cholinesterase (CHE), Glutamat-Oxalacetat-Transaminase (GOT), Glutamat-Pyruvat-Transaminase (GPT), gamma-Glutamyltransferase (GT), Creatinkinase (CK), creatinine, c-reactive protein (CRP) and clinical history of postoperative complications (bleeding, infections) were collected. RESULTS Out of 698 registered parameters 10,5 % were differing from the reference parameters. There were no abnormal bleedings or complications which could have been predicted by blood tests. CONCLUSIONS The preoperative blood tests have no influence on the management of an elective ear operation. A thorough medical patient's and family history should be taken and may be added by a calculated analysis of special blood tests.

This article takes the reader through a journey of the history of the phenotypic tests for hemostasis and thrombosis starting from the most simple (which were based on the visual inspection and recording of the time needed for native whole blood to clot) to the more complex ones based on the addition to plasma of exogenous substances, use of sophisticated coagulometers or synthetic substrates, and use of computer software to record coagulation times or visualize coagulation tracings and thrombin generation curves. One can see how the simple tests evolved over the years and how such old and time-honored tests as thrombin generation and thromboelastography, devised more than 50 years ago and neglected for many years, are now gaining momentum thanks to the progress made by the technology combined with a better understanding of the coagulation mechanisms. This progress notwithstanding, it should be realized that current tests are still somewhat far from being adequate to investigate hemostasis and thrombosis. The challenge in the future will be to devise newer tests mimicking more closely what occurs in vivo.

Background: Most cancer patients with metastatic disease have abnormal coagulation parameters. Although many abnormal blood coagulation tests have been reported in malignancies, there is little agreement regarding which tests are most useful to predict disease progression and hence this study was undertaken. Methods: In this prospective study, baseline and special coagulation tests were performed on 23 patients with ovarian adenocarcinoma. The baseline tests were PT, APTT, TT and platelet count. The special tests included factor VIII, factor IX and fibrinogen assay and semiquantitative measurement of D-dimer and FDP levels The cases were grouped into early and advanced disease groups. The results of the coagulation tests were analysed using suitable statistical methods. The results were compared between limited and advanced disease by chi square and Mann Whitney U test Results: The percentage of cases with increased D-dimer and fibrin degradation products (FDP) values were higher in the advanced disease compared to early disease. Two cases in stage IV had DIC. The PT, APTT, TT and platelet count did not show any statistically significant differences between the early and advanced disease groups. Factor VIII, factor IX and fibrinogen levels were not significantly different between two groups. Conclusion: Elevated D dimer& FDP are associated with advanced stage ovarian adenocarcinoma.

Acute idiopathic fatty liver of pregnancy was observed in a 34-year-old patient. Mother and child survived this complication which has happened in only 10% of the 69 histologically verified cases. On the basis of coagulation studies it may be assumed that consumption coagulopathy had been present initially. This could be pathogenetically relevant in the development of fatty liver of pregnancy.

A dosage of 7500 IU heparin calcium (Calciparin) was administered subcutaneously twice daily in 15 probands. Prior to and after the 1st and 7th injection heparin levels were determined in plasma and coagulation studies were done. The highest heparin levels were found around 4 hours after the injection. They were significantly higher after the 7th injection than after the 1st. Values decreased markedly after 8 hours. After 10-12 hours they approached the initial values, however remained significantly increased. The appropriate changes were seen in activated partial thromboplastin time, thrombin time and reaction- and clotting time in the thrombelastogram. Activity and concentration of antithrombin III decreased by about 10%. Fibrinogen and platelets remained largely unaffected. The results show that twice daily subcutaneous injections of 7500 IU heparin calcium are able to close the anticoagulation gap in plasma which occurs with administration of twice 5000 IU between two injections.

BACKGROUND AND OBJECTIVE: Cerebral embolism may have different causes with sometimes serious consequences. If no specific reason can be found, paradoxical embolization through a persistent foramen ovale (PFO) is increasingly as a cause of the cerebral ischaemia. This study was undertaken to ascertain whether in patients with cerebral embolism occlusion of a PFO with a transcatheter technique can prevent further cerebral emboli. PATIENTS AND METHODS: Indications for transcatheter occlusion were based on neurological signs (ischaemic stroke), cardiovascular diagnosis, and coagulation tests. Between August 1991 and July 1996, transcatheter occlusion of a PFO was performed in 28 fully anticoagulated patients (median age 37.8 [15.4-65.4] years). The mean PFO diameter was 9.5 mm (3-17), mean duration of fluoroscopy 18.3 (8.7-43.1) min. The Rashkind device was implanted in three patients, the Sideris buttoned device in 25. During the follow-up period (2-64 months; mean 13 months) renewed neurological symptoms occurred in only one patient. Transoesophageal echocardiography excluded thrombi on the implanted device or in the left atrium, and a residual PFO. The cause of the one neurological episode is therefore not clear. All other patients have remained free of symptoms and recurrence without anticoagulation after placement of the device. CONCLUSIONS: Transcatheter occlusion of a PFO is a relatively simple and safe procedure. Our results suggest that it can at least lower the incidence of further cerebral embolizations. The clinical value of the method in comparison with anticoagulation requires further study.