Management of pregnancy and delivery in congenital fibrinogen disorders: communication from the ISTH SSC Subcommittee on Factor XIII and Fibrinogen.

Congenital fibrinogen disorders (CFDs) are a heterogeneous group of rare congenital quantitative and/or qualitative fibrinogen deficiencies. The spectrum of molecular anomalies is broad, leading to several subtypes of fibrinogen disorders (ie, afibrinogenemia, hypofibrinogenemia, dysfibrinogenemia, and hypodysfibrinogenemia). Pregnancy in women with CFDs is a high-risk clinical situation, with an increased tendency for miscarriages, bleeding, and thrombosis. Even though it is well established that management of such pregnancies requires a multidisciplinary approach involving specialists (hematologists and maternal/fetal medicine experts with expertise in the management of inherited bleeding disorders), specific guidelines are lacking. In this International Society on Thrombosis and Haemostasis (ISTH) Scientific and Standardization Committee communication, we aim to propose an expert consensus opinion with literature evidence where available on the strategy for management of pregnancy, delivery, and puerperium in CFDs.

Structural and Functional Characterization of Four Novel Fibrinogen Mutations in FGB Causing Congenital Fibrinogen Disorder.

Congenital fibrinogen disorders are caused by mutations in genes coding for fibrinogen and may lead to various clinical phenotypes. Here, we present a functional and structural analysis of 4 novel variants located in the FGB gene coding for fibrinogen Bß chain-heterozygous missense BßY416C and BßA68S, homozygous nonsense BßY345*, and heterozygous nonsense BßW403* mutations. The cases were identified by coagulation screening tests and further investigated by various methods. Fibrin polymerization had abnormal development with decreased maximal absorbance in all patients. Plasmin-induced fibrin degradation revealed different lytic phases of BßY416C and BßW403* than those of the control. Fibrinopeptide cleavage measured by reverse phase high pressure liquid chromatography of BßA68S showed impaired release of fibrinopeptide B. Morphological properties, studied through scanning electron microscopy, differed significantly in the fiber thickness of BßY416C, BßA68S, and BßW403*, and in the fiber density of BßY416C and BßW403*. Finally, homology modeling of BßA68S showed that mutation caused negligible alternations in the protein structure. In conclusion, all mutations altered the correct fibrinogen function or structure that led to congenital fibrinogen disorders.

Uso de concentrados de fibrinógeno para el tratamiento de la hipofibrinogenemia adquirida / Use of Fibrinogen Concentrates for the Treatment of Acquired Hypofibrinogenemia

Resumen Introducción: Un adecuado manejo del sangrado debe incluir la correcta valoración y eventual reposición de fibrinógeno. Las fuentes tradicionales de este elemento hemostático incluyen el plasma fresco congelado y los crioprecipitados. Los concentrados liofilizados de fibrinógeno humano (CFH) son una alternativa terapéutica novedosa en el mercado chileno. Objetivo: Este estudio describe el curso clínico de los primeros pacientes en nuestra institución requirentes de CFH, dentro de un algoritmo de reposición hemostática por metas. Materiales y Método: Serie de pacientes con hipofibrinogenemia secundaria a sangrado perioperatorio severo, en los que se utilizó CFH como método de reposición de fibrinógeno. Se utilizó tromboelastometría para definir dosis. Se registraron variables demográficas, operatorias, complicaciones y seguimiento hasta los 3 meses. Resultados: Se utilizaron CFH en 18 pacientes. La mediana de edad fue 40,7 (56,5-63) años y dos tercios de los pacientes fueron de sexo masculino. Fallecieron 5 pacientes de la serie. Todos los pacientes requirieron manejo posoperatorio en una unidad de cuidados intensivos. Ocho pacientes fueron sometidos a cirugía cardiaca. El uso de hemocomponentes y concentrados liofilizados fue heterogéneo, pero en todos los casos su uso fue determinado por tromboelastometría. Ningún paciente fue reintervenido a causa de sangrado posoperatorio. Conclusión: El uso de concentrados de fibrinógeno humano dentro de un algoritmo de manejo de sangrado guiado por tromboelastometría, es un recurso hemostático factible en la realidad nacional. El impacto clínico de esta intervención requiere una subsiguiente evaluación basada en la evidencia.

Introduction: An adequate bleeding management should include a proper assessment of fibrinogen values and consequent replacement. Traditional sources for this hemostatic element include fresh frozen plasma and cryoprecipitates. Lyophilized human fibrinogen concentrates are a novel therapeutic alternative for the chilean market. Aim: This study aims to describe the clinical course of the first patients in our institution receiving fibrinogen concentrates, included in a goal directed hemostatic management algorithm. Materials and Method: Case series of patients with hypofibrinogenemia secondary to severe perioperative bleeding, in which fibrinogen concentrate was used for fibrinogen replacement. Thromboelastometry was used to define dose regimens. Demographic and surgical variables, complications and follow-up up to 3 months were registered. Results: Fibrinogen concentrate was used in 18 patients. Median age was 40.7 (56.5-63) years, and two thirds of the patients were male. Five patients died. All of the cases required postoperative intensive care. Eight patients underwent cardiac surgery. There was a heterogenic use of blood derived products and lyophilized concentrates, but in all cases its use was guided by thromboelastometry. No patients needed a secondary exploration due to bleeding. Conclusion: The use of human fibrinogen concentrate included in a bleeding management algorithm is a feasible hemostatic resource in the chilean current situation. The clinical impact of this intervention requires further evidence-based evaluation.

A novel variant fibrinogen, AαE11del, demonstrating the importance of AαE11 residue in thrombin binding.

INTRODUCTION: We identified a novel heterozygous AαE11del variant in a patient with congenital dysfibrinogenemia. This mutation is located in fibrinopeptide A (FpA). We analyzed the effect of AαE11del on the catalyzation of thrombin and batroxobin and simulated the stability of the complex structure between the FpA fragment (AαG6-V20) peptide and thrombin. MATERIALS AND METHODS: We performed fibrin polymerization and examined the kinetics of FpA release catalyzed by thrombin and batroxobin using purified plasma fibrinogen. To clarify the association between the AαE11 residue and thrombin, we calculated binding free energy using molecular dynamics simulation trajectories. RESULTS: Increasing the thrombin concentration improved release of FpA from the patient's fibrinogen to approximately 90%, compared to the previous 50% of that of normal fibrinogen. Fibrin polymerization of variant fibrinogen also improved. In addition, greater impairment of variant FpA release from the patient's fibrinogen was observed with thrombin than with batroxobin. Moreover, the calculated binding free energy showed that the FpA fragment-thrombin complex became unstable due to the missing AαE11 residue. CONCLUSIONS: Our findings indicate that the AαE11 residue is involved in FpA release in thrombin catalyzation more than in batroxobin catalyzation, and that the AαE11 residue stabilizes FpA fragment-thrombin complex formation.

The ß-chain mutation p.Trp433Stop impairs fibrinogen secretion: A novel nonsense mutation associated with hypofibrinogenemia.

BACKGROUND: Congenital hypofibrinogenemia is characterized by proportional decreases in fibrinogen activity and immunoreactive fibrinogen levels. Here, we describe a new case with the bleeding risk identified in our hospital. METHODS: The proband was cut and bled for 3 h. Coagulation testing, gene analysis, thrombelastogram, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), in vitro plasmid construction, and functional analyses were performed to explore the pathogenic mechanism. RESULTS: Coagulation testing of the male proband revealed low levels of fibrinogen detected by two methods (the Clauss method and the PT-derived method); his two sons had normal coagulation results. DNA sequencing of the proband revealed a heterozygous point mutation in exon 8 of the FGB gene causing Trp→Stop substitution and a polymorphic site (p.Leu92Phe). Human Trp433 was found to be highly conserved. SDS-PAGE showed that the fibrinogen level of the proband was markedly lower than that of healthy controls. Using high-performance liquid chromatography-mass spectrometry, a mutated Bß chain was not detected in circulation. In vitro expression analyses indicated that the mutation affected the secretion of fibrinogen. The TEG results indicated that the proband had a prolonged K time, a lower CI value, and a lower angle value. CONCLUSION: We report a new case with a novel nonsense mutation that resulted in hypofibrinogenemia. The results indicate that the nonsense mutation may cause misfolding of the D domain, which then affects the secretion of fibrinogen.

Novel variant fibrinogen γp.C352R produced hypodysfibrinogenemia leading to a bleeding episode and failure of infertility treatment.

INTRODUCTION: We identified a patient with a novel heterozygous variant fibrinogen, γp.C352R (Niigata II; N-II), who had a bleeding episode and failed infertility treatment and was suspected to have hypodysfibrinogenemia based on low and discordant fibrinogen levels (functional assay 0.33 g/L, immunological assay 0.91 g/L). We analyzed the mechanism of this rare phenotype of a congenital fibrinogen disorder. MATERIALS AND METHODS: Patient plasma fibrinogen was purified and protein characterization and thrombin-catalyzed fibrin polymerization performed. Recombinant fibrinogen-producing Chinese hamster ovary (CHO) cells were established and the assembly and secretion of variant fibrinogen analyzed by ELISA and western blotting. RESULTS: Purified N-II plasma fibrinogen had a small lower molecular weight band below the normal γ-chain and slightly reduced fibrin polymerization. A limited proportion of p.C352R fibrinogen was secreted into the culture medium of established CHO cell lines, but the γ-chain of p.C352R was synthesized and variant fibrinogen was assembled inside the cells. CONCLUSION: We demonstrated that fibrinogen N-II, γp.C352R was associated with markedly reduced secretion of variant fibrinogen from CHO cells, that fibrin polymerization of purified plasma fibrinogen was only slightly affected, and that fibrinogen N-II produces hypodysfibrinogenemia in plasma.

Recombinant γY278H Fibrinogen Showed Normal Secretion from CHO Cells, but a Corresponding Heterozygous Patient Showed Hypofibrinogenemia.

We identified a novel heterozygous hypofibrinogenemia, γY278H (Hiroshima). To demonstrate the cause of reduced plasma fibrinogen levels (functional level: 1.12 g/L and antigenic level: 1.16 g/L), we established γY278H fibrinogen-producing Chinese hamster ovary (CHO) cells. An enzyme-linked immunosorbent assay demonstrated that synthesis of γY278H fibrinogen inside CHO cells and secretion into the culture media were not reduced. Then, we established an additional five variant fibrinogen-producing CHO cell lines (γL276P, γT277P, γT277R, γA279D, and γY280C) and conducted further investigations. We have already established 33 γ-module variant fibrinogen-producing CHO cell lines, including 6 cell lines in this study, but only the γY278H and γT277R cell lines showed disagreement, namely, recombinant fibrinogen production was not reduced but the patients' plasma fibrinogen level was reduced. Finally, we performed fibrinogen degradation assays and demonstrated that the γY278H and γT277R fibrinogens were easily cleaved by plasmin whereas their polymerization in the presence of Ca2+ and "D:D" interaction was normal. In conclusion, our investigation suggested that patient γY278H showed hypofibrinogenemia because γY278H fibrinogen was secreted normally from the patient's hepatocytes but then underwent accelerated degradation by plasmin in the circulation.

Pro-Con Debate: Fibrinogen Concentrate or Cryoprecipitate for Treatment of Acquired Hypofibrinogenemia in Cardiac Surgical Patients.

Cryoprecipitate has been the gold standard for treating acquired hypofibrinogenemia in cardiac surgery for nearly 50 years. More recently, fibrinogen concentrate has been used off-label in the United States and is the standard in European countries and Canada to treat the acquired hypofibrinogenemia during cardiac surgery. Fibrinogen concentrate has multiple potential advantages including rapid reconstitution, greater dose predictability, viral inactivation during processing, and reduced transfusion-related adverse events. However, because fibrinogen concentrate lacks the other components contained in the cryoprecipitate, it may not be the "ideal" product for replacing fibrinogen in all cardiac surgical patients, particularly those with longer cardiopulmonary bypass duration. In this Pro-Con commentary article, we discuss the advantages and disadvantages of using fibrinogen concentrate and cryoprecipitate to treat acquired hypofibrinogenemia in cardiac surgical patients.

Acquired hypofibrinogenemia in a patient with multiple myeloma.

We report a case of acquired hypofibrinogenemia with multiple myeloma presenting λ-type IgG monoclonal protein. The patient had anemia and renal deficiency, and also developed bleeding tendency due to severe coagulopathy. Her fibrinogen level was under the detectable limits in a functional assay. Enzyme-linked immunosorbent assay (ELISA) and immunoblotting analysis results were consistent with functional assay results, and deficiency patterns observed in cross-mixing tests for PT and aPTT confirmed the diagnosis of hypofibrinogenemia. To determine the cause of hypofibrinogenemia, we purified the patient's immunoglobulin via protein A agarose, and confirmed that fibrinogen was included in the bound fraction, strongly indicating paraprotein interference with fibrinogen. As accelerated removal of fibrinogen was indicated, we incubated the patient's plasma up to 48 h, but did not observe significant loss of fibrinogen. In sharp contrast, fibrinogen returned to below the detection level 12 h after infusion of fresh frozen plasma. These findings support leukocyte-mediated fibrinogen removal, rather than paraprotein-triggered fibrinogen instability. Surprisingly, the patient's paraprotein was IgG2, but we speculate the amount of paraprotein (IgG 5346 mg/dL) compensated for lower affinity to Fcγ receptors.

Whole Blood Thromboelastometry by ROTEM and Thrombin Generation by Genesia According to the Genotype and Clinical Phenotype in Congenital Fibrinogen Disorders.

The outcome of congenital fibrinogen defects (CFD) is often unpredictable. Standard coagulation assays fail to predict the clinical phenotype. We aimed to assess the pheno- and genotypic associations of thrombin generation (TG) and ROTEM in CFD. We measured fibrinogen (Fg) activity and antigen, prothrombin fragments F1+2, and TG by ST Genesia® with both Bleed- and ThromboScreen in 22 patients. ROTEM was available for 11 patients. All patients were genotyped for fibrinogen mutations. Ten patients were diagnosed with hypofibrinogenemia, nine with dysfibrinogenemia, and three with hypodysfibrinogenemia. Among the 17 mutations, eight were affecting the Fg γ chain, four the Fg Bß chain, and five the Fg Aα chain. No statistical difference according to the clinical phenotypes was observed among FGG and FGA mutations. Median F1+2 and TG levels were normal among the different groups. Fg levels correlated negatively with F1+2 and peak height, and positively with lag time and time to peak. The pheno- and genotypes of the patients did not associate with TG. FIBTEM by ROTEM detected hypofibrinogenemia. Our study suggests an inverse link between low fibrinogen activity levels and enhanced TG, which could modify the structure-function relationship of fibrin to support hemostasis.

Effect of hypofibrinogenemia on obstetrical disseminated intravascular coagulation in Japan in 2018: a multicenter retrospective cohort study.

Japanese obstetrical hemorrhage recommendations state that not only pregnant women with an obstetrical disseminated intravascular coagulation (DIC) score ≥ 8 points but also those with fibrinogen levels ≤ 1.5 g/L have a high risk of maternal death and warrant blood transfusion. Our aim was to demonstrate the potential of fibrinogen levels ≤ 1.5 g/L as predictors of a Japanese obstetrical DIC score of ≥ 8. We included 595 participants with blood loss ≥ 1000 mL during vaginal delivery or ≥ 2000 mL during cesarean delivery. The frequency and volume of red blood cell (RBC), fresh-frozen plasma, platelet concentrate (PC), and fibrinogen administration in women with a DIC score of ≥ 8 and fibrinogen levels of ≤ 1.5 g/L were significantly higher than controls (P < 0.0001). Multivariate analysis demonstrated that a score of ≥ 3 was associated with RBC or fibrinogen administration and a score of ≥ 5 was associated with PC transfusion. Fibrinogen levels ≤ 1.89 g/L and ≤ 2.44 g/L were associated with PC transfusion and fibrinogen administration, respectively. Fibrinogen levels ≤ 1.5 g/L may have similar potential to a DIC score of ≥ 8 points for detecting obstetrical DIC in Japan.

Congenital dysfibrinogenemia caused by γAla327Val mutation: structural abnormality of D region.

BACKGROUND: : Congenital dysfibrinogenemia (CD) is a coagulation disorder caused by mutations in the fibrinogen genes, which result in abnormal fibrinogen function. However, the precise pathogenesis underlying it remains unclear. METHODS: : In this study, we identified a novel heterozygous mutation in an asymptomatic patient with CD caused by γ Ala327Val mutation. Aimed to investigate the pathogenesis, functional studies of fibrinogen isolated from the proband and her family members were performed, such as coagulation function, fibrinogen aggregation test, and fibrin clot lysis test. Coagulation was monitored using a thromboelastometer, and the fibrin clot network structure was observed by scanning electron microscopy. The effect of the mutation on fibrinogen structure and function was predicted by molecular modeling. RESULTS: : The fibrinogen activity concentration in patients with CD was significantly lower than that in healthy individuals, indicating that fibrinogen activity was low. Proband's fibrinogen activity concentration was 0.75 g/L(Clauss method) and antigen concentration (immune turbidimetry method) was 1.59 g/L(normal reference range for both parameters: 2.0-4.0 g/L). Thromboelastography showed that the K value of patients with CD was higher than that of healthy individuals and Angle values were decreased, indicating that mutation impaired fibrinogen function. Compared to fibrinogen from healthy individuals, fiber network structure of the proband was loose, pore size was increased, and fiber branch nodes were increased. CONCLUSIONS: : Ala327Val heterozygous missense mutation leads to changes in the structure of fibrinogen D region and impairs the aggregation function of fibrinogen. This mutation is reported here for the first time.

Rare severe hypofibrinogenemia induced by tissue plasminogen activator in stroke patients: Case report.

RATIONALE: Severe hypofibrinogenemia after intravenous thrombolysis (IVT) with recombinant tissue plasminogen activator (rt-PA) is rare and easily overlooked, but hypofibrinogenemia increases the risk of major bleeding. However, it is unclear when hypofibrinogenemia reaches the peak and when hypofibrinogenemia is resolved. PATIENT CONCERNS: Case 1 was of a 66-year-old man who was hospitalized due to sudden onset of vague speech and right hemiplegia for 4 hours. Case 2 was of an 84-year-old woman who was hospitalized for sudden onset of left hemiplegia and vague speech for 4 hours. In case 1, fibrinogen levels decreased from normal values to <0.25 g/L within 4.5 hours after commencing IVT and returned to normal at 35 hours later. In case 2, fibrinogen levels decreased from 1.1 to <0.25 g/L within 2 hours after commencing IVT and normalized 36.5 hours later. DIAGNOSES: Both patients were diagnosed with rt-PA-related hypofibrinogenemia. INTERVENTIONS: No antiplatelet or symptomatic treatment was administered during the period of hypofibrinogenemia. OUTCOMES: Fibrinogen levels gradually recovered. In case 1, the patient did not experience cerebral hemorrhage during hypofibrinogenemia. His symptoms improved significantly within 1 week. In case 2, repeat computed tomography revealed minor cerebral hemorrhage, but no deterioration in her condition was noted until she was discharged. LESSONS: Rapid, severe, and prolonged hypofibrinogenemia may occur after IVT with rt-PA, which may increase the risk of massive hemorrhage and affect the related therapy. Prompt diagnosis of hypofibrinogenemia is important for preventing complications. We recommend checking the fibrinogen levels routinely after IVT. Fibrinogen replacement therapy and platelet transfusion are the main management routes for rt-PA-related symptomatic intracranial hemorrhage.

Comparison of different activators of coagulation by turbidity analysis of hereditary dysfibrinogenemia and controls.

Turbidity analysis is widely used as a quantitative technique in hereditary dysfibrinogenemia. We aimed to compare several coagulation triggers in hereditary dysfibrinogenemia and control plasmas. We included 20 patients with hereditary dysfibrinogenemia, 19 with hotspot mutations Aα Arg35His (n = 9), Aα Arg35Cys (n = 2), γ Arg301His (n = 6), γ Arg301Cys (n = 2), and one with Aα Phe27Tyr, and a commercial pooled normal plasma. Fibrin polymerization was activated by bovine or human thrombin or tissue factor (TF), in the presence or absence of tissue type plasminogen activator. The lag time (min), slope (mOD/s), maximum absorbance (MaxAbs, mOD), and area under the curve (AUCp, OD s) were calculated from the fibrin polymerization curves and the time for 50% clot degradation (T50, min), AUCf (OD s) and the overall fibrinolytic potential from fibrinolysis curves. The lag time was significantly shorter and AUC increased in Aα Arg35His patients with bovine thrombin as compared with human thrombin. The MaxAbs and AUCp were significantly higher in γArg301His patients with bovine thrombin compared with human thrombin. Fibrin polymerization parameters of patients' samples were closer to those of control when assessed with TF compared with both human and bovine thrombin. T50 and overall fibrinolytic potential were similar in all samples regardless of the coagulation trigger used, however, with TF the AUCf of Aα Arg35His and γ Arg301His groups were significantly decreased compared with control. Bovine and human thrombin cannot be used equally for studying fibrin polymerization in hotspot hereditary dysfibrinogenemia or control plasmas.

Transfusion with Cryoprecipitate for Very Low Fibrinogen Levels Does Not Affect Bleeding or Survival in Critically Ill Cirrhosis Patients.

BACKGROUND: Fibrinogen (FIB) levels less than 150 mg/dL have been associated with increased rates of bleeding and lower survival in critically ill cirrhosis patients. OBJECTIVE: We aimed to determine if treatment with cryoprecipitate (CRYO) for low FIB levels is associated with bleeding outcomes or survival. METHODS: A total of 237 cirrhosis patients admitted to an intensive care unit at a tertiary care liver transplant center with initial FIB levels less than 150 mg/dL were retrospectively assessed for CRYO transfusion, bleeding events, and survival outcomes. RESULTS: The mean MELD score was 27.2 (95% confidence interval [CI]: 26.0-28.3) and CLIF-C acute on chronic liver failure score was 53.4 (51.9-54.8). Ninety-nine (41.8%) were admitted for acute bleeding and the remainder were admitted for nonbleeding illnesses. FIB level on admission correlated strongly with disease severity. After adjusting for disease severity, FIB on admission was not an independent predictor of 30-day survival (hazard ratio [HR]: 0.99, 95% CI: 0.99-1.01, p = 0.68). CRYO transfusion increased FIB levels but had no independent effect on mortality or bleeding complications (HR: 1.10, 95% CI: 0.72-1.70, p = 0.65). CONCLUSION: In cirrhosis patients with critical illness, low FIB levels on presentation reflect severity of illness but are not independently associated with 30-day mortality. Treatment of low FIB with CRYO also does not affect survival or bleeding complications, suggesting FIB is an additional marker of severity of illness but is not itself a direct factor in the pathophysiology of bleeding in critically ill cirrhosis patients.

Screening method for congenital dysfibrinogenemia using clot waveform analysis with the Clauss method.

INTRODUCTION: Congenital fibrinogen disorders (CFDs) are classified as afibrinogenemia or hypofibrinogenemia (Hypo), dysfibrinogenemia (Dys), or hypodysfibrinogenemia (Hypodys), according to functional and antigenic fibrinogen concentrations. However, in routine laboratory tests, plasma fibrinogen levels are mostly measured using the functional Clauss method and not as an antigenic level. Therefore, it is difficult to discriminate CFD from acquired hypofibrinogenemia (aHypo). To establish a screening method for CFD, we investigated the parameters of clot waveform analysis (CWA) from the Clauss method. METHODS: We compared fibrinogen concentrations determined using Clauss and prothrombin time (PT)-derived methods for 67 aHypo and CFD cases (19 Dys, 4 Hypodys, and 1 Hypo determined using antigen levels and DNA sequence analysis) with a CS-2400 instrument, and the CWA parameters, dH and Min1, were analyzed automatically with an on-board algorithm. dH and Min1 are the maximum change in transmittance at the end of coagulation and the maximum velocity of transmittance change during coagulation, respectively. RESULTS: Clauss/PT-derived ratios detected 18 cases of Dys and Hypodys but no Hypo cases, whereas Clauss/dH plus Clauss/Min1 ratios were calculated from fibrinogen concentration using the Clauss method and CWA parameters detected 21 cases of Dys and Hypodys and one Hypo case. Moreover, the Clauss/PT-derived ratio and Clauss/dH plus Clauss/Min1 ratio detected 22 cases of Dys and Hypodys cases and one Hypo case. CONCLUSION: This report demonstrates that CWA parameters of the Clauss method, Clauss/dH plus Clauss/Min1 ratio, screened Dys patients with a higher rate, whereas Clauss/PT-derived ratios did not.

Detection of hypofibrinogenemia during cardiac surgery: a comparison of resonance-based thrombelastography with the traditional Clauss method.

: Bleeding after cardiac surgery is associated with significant morbidity and mortality. Hypofibrinogenemia is a crucial factor for bleeding in this setting and may be rapidly detected using point-of-care viscoelastic tests (POC-VET). However, the correlation of POC-VET with conventional coagulation assays is still unclear. The current study aimed to correlate resonance-based POC-VET assays (Haemonetics TEG 6s) with the traditional nonrapid Clauss method. Another aim was to identify a cut-off value for the detection of hypofibrinogenemia (fibrinogen plasma level below 150 mg/dl) focusing on the maximum amplitude of the TEG 6s citrated functional fibrinogen (CFF) assay. Adult patients undergoing cardiac surgery were screened for inclusion in this single-centre retrospective cohort study. Inclusion criteria were the availability of a TEG assay and timely corresponding laboratory results. Calculation of a CFF-maximum amplitude (CFF-MA) cut-off value was performed using receiver operating curve analysis in the baseline cohort and validated in the control cohort. The best correlation with the Clauss method was observed for the CFF-MA (r = 0.77; P < 0.0001) compared with the citrate kaolin maximum amplitude assay (r = 0.57; P < 0.0001) and the citrate kaolin heparinase maximum amplitude assay (r = 0.67; P < 0.0001). A cut-off value of 19.9 mm for the CFF-MA was calculated [area under the curve 0.87 (95% confidence interval: 0.82-0.92; P < 0.0001)]. This cut-off value had a sensitivity of 81.8% and a specificity of 71.1% for identification of hypofibrinogenemia in the control cohort. The resonance-based thrombelastography analyser can identify hypofibrinogenemia. Future clinical studies should investigate whether cut-off value guided coagulation therapy with POC-VET may improve patient outcomes in patients who suffer from bleeding complications.

Congenital dysfibrinogenaemia presented with preterm premature rupture of the membranes and vaginal bleeding.

A 26-year-old woman was found to have congenital dysfibrinogenaemia after presenting to our hospital with premature rupture of the membranes and vaginal bleeding. Given the absence of clear guidelines for the management of pregnancy complicated by dysfibrinogenaemia, we followed expert consensus that exists among published works, with some modifications. This case was managed by a multidisciplinary team of obstetrics-gynaecology, haematology and paediatric haematology. Here we review how the patient presented, the investigations that led to the diagnosis and the treatment options.

Pharmacological Blockade of Glycoprotein VI Promotes Thrombus Disaggregation in the Absence of Thrombin.

OBJECTIVE: Atherothrombosis occurs upon rupture of an atherosclerotic plaque and leads to the formation of a mural thrombus. Computational fluid dynamics and numerical models indicated that the mechanical stress applied to a thrombus increases dramatically as a thrombus grows, and that strong inter-platelet interactions are essential to maintain its stability. We investigated whether GPVI (glycoprotein VI)-mediated platelet activation helps to maintain thrombus stability by using real-time video-microscopy. Approach and Results: We showed that GPVI blockade with 2 distinct Fab fragments promoted efficient disaggregation of human thrombi preformed on collagen or on human atherosclerotic plaque material in the absence of thrombin. ACT017-induced disaggregation was achieved under arterial blood flow conditions, and its effect increased with wall shear rate. GPVI regulated platelet activation within a growing thrombus as evidenced by the loss in thrombus contraction when GPVI was blocked, and the absence of the disaggregating effect of an anti-GPVI agent when the thrombi were fully activated with soluble agonists. The GPVI-dependent thrombus stabilizing effect was further supported by the fact that inhibition of any of the 4 key immunoreceptor tyrosine-based motif signalling molecules, src-kinases, Syk, PI3Kß, or phospholipase C, resulted in kinetics of thrombus disaggregation similar to ACT017. The absence of ACT017-induced disaggregation of thrombi from 2 afibrinogenemic patients suggests that the role of GPVI requires interaction with fibrinogen. Finally, platelet disaggregation of fibrin-rich thrombi was also promoted by ACT017 in combination with r-tPA (recombinant tissue plasminogen activator). CONCLUSIONS: This work identifies an unrecognized role for GPVI in maintaining thrombus stability and suggests that targeting GPVI could dissolve platelet aggregates with a poor fibrin content.

Hypofibrinogenemia Caused by Hemocoagulase Injection: A Retrospective Study on Clinical Laboratory Findings.

Objective Hemocoagulase injection based on the venom of Agkistrodon halys Pallas is widely used in the treatment of hemorrhagic disorders. This study aimed to characterize the clinical laboratory findings of hemocoagulase-induced hypofibrinogenemia as the associated adverse reaction of hemocoagulase injection.Methods We retrospectively enrolled 27 in-patients who were treated with hemocoagulase injection for hemoptysis and developed hypofibrinogenemia during the period of January 1, 2015 to March 31, 2018. Clinical data were collected and investigated, including clinical manifestations, hemostatic and fibrinolytic parameters, dosage of hemocoagulase, the medication time, and the cryoprecipitate blood product infusion. Differences in fibrinogen, D-dimer, and fibrin/fibrinogen degradation products (FDP) before, during, and after the application of hemocoagulase injection were analyzed statistically.Results Plasma fibrinogen level during medication of hemocoagulase injection decreased significantly compared to that before the treatment (F=1.80, P<0.001), with the average decrease of 2.28 g/L (0.63-3.9 g/L). After withdrawal, fibrinogen level increased significantly compared to that during the medication (F=-1.20, P<0.001), but was still lower than that before the medication (F=0.59, P=0.03). The D-dimer level and the FDP level after withdrawal decreased significantly compared to the levels during the medication (F=0.83, P=0.002; Wilcoxon-test, Z=-4.54, P<0.001). Spearman's correlation analyses did not find either fibrinogen change during-before the administration or FDP change after-during the administration was associated with the dosage of hemocoagulase (r=-0.17, P=0.40; r=-0.28, P=0.15; respectively) and the time of recovery from hypofibrinogenemia (r=-0.45, P=0.05; r=0.13, P=0.61; respectively).Conclusion Monitoring both clotting and fibrinolysis parameters is essential in the management of hemoptysis patients treated with hemocoagulase injection. Clinicians should be aware of hypofibrinogenemia and consider discontinuation of the administration of hemocoagulase whenever necessary.