Blutungsneigung

Patients suffering from hemorrhagic disorders often present with only minimal bleeding during surgery or injuries. However, some patients have life-threatening bleeding. Simple screening tests can be used to find the cause of the bleeding: patient and family histories provide information on whether the bleeding tendency is hereditary or acquired. Clinical examination can reveal the bleeding type. Measurement of platelet count can be used to exclude thrombocytopenia. Coagulation tests, such as prothrombin time (PT, Quick) and activated partial thromboplastin time (aPTT) can supply initial information concerning deficiency states of coagulation factors. Bleeding time is often prolonged in patients suffering from von Willebrand disease, thrombocytopenia or thrombocytopathy. If—due to the results of these screening tests—further testing of particular coagulation factors or platelet function is needed, then patients should be referred to a centre specialized in blood coagulation.     

Hemostatic complications in leukemic patients

With clinical vigilance and laboratory tests of platelet and coagulation factor function, the clinician can promptly recognize and treat hemostatic disorders in leukemic patients. For example, laboratory values are strikingly abnormal in disseminated intravascular coagulation. Prompt neutralization of the underlying cause of the coagulopathy is essential. Platelet and coagulation factors may have to be replaced if the disorder is severe. Diffuse petechiae, purpura, mucous membrane bleeding, and hemorrhage around venipuncture or infusion sites indicate thrombocytopenia. Vigorous platelet replacement is necessary to prevent massive intracranial of gastrointestinal hemorrhage. Platelet dysfunction may cause spontaneous bleeding or immediate or delayed hemorrhage after surgery. The abnormality is often evident in peripheral blood smear or indicated by bleeding time or aggregation studies. If possible, sufficient autologous platelets should be infused to return the bleeding time to normal. Immune thrombocytopenic purpura may be easy to diagnose when the reduction in the circulating platelet count is compared with the normal number of marrow megakaryocytes. But attempts to increase platelet count by platelet transfusions may be frustrating. Treatment involves high doses of corticosteroids, followed by splenectomy if necessary.     

An overview of platelet indices and methods for evaluating platelet function in thrombocytopenic patients

Thrombocytopenia is associated with bleeding risk. However, in thrombocytopenic patients, platelet count does not correlate with bleeding risk and other factors are thus likely to contribute to this risk. This review presents currently available platelet‐related markers available on automated haematology analysers and commonly used methods for testing platelet function. The test principles, advantages and disadvantages of each test are described. We also evaluate the current literature regarding the clinical utility of the test for prediction of bleeding in thrombocytopenia in haematological and oncological diseases. We find that several platelet‐related markers are available, but information about the clinical utility in thrombocytopenia is limited. Studies support that mean platelet volume (MPV) can aid diagnosing the cause of thrombocytopenia and low MPV may be associated with bleeding in thrombocytopenia. Flow cytometry, platelet aggregometry and platelet secretion tests are used to diagnose specific platelet function defects. The flow cytometric activation marker P‐selectin and surface coverage by the Cone‐and‐Plate[let] analyser predict bleeding in selected thrombocytopenic populations. To fully uncover the clinical utility of platelet‐related tests, information about the prevalence of platelet function defects in thrombocytopenic conditions is required. Finally, knowledge of the performance in thrombocytopenic samples from patients is essential.     

Clinical approach to the patient with unexpected bleeding

Bleeding can be considered unexpected if it is disproportionate to the intensity of the haemostatic stress in a patient with no known haemorrhagic disorder or if it occurs in a patient in whom a bleeding disorder has been characterized but is adequately treated. A thorough history usually allows the clinician to predict reasonably accurately whether the patient is likely to have a systemic haemostatic defect (and if so whether it is congenital or acquired), or whether the bleeding likely has a purely anatomical basis. The nature of bleeding is instructive with respect to preliminary categorization. Thus, mucocutaneous bleeding suggests defects of primary haemostasis (disordered platelet-vascular interactions). Bleeding into deeper structures is more suggestive of coagulation defects leading to impaired fibrin clot formation, and delayed bleeding after primary haemostasis is characteristic of hyperfibrinolysis. Localized bleeding suggests an anatomical cause, although an underlying haemostatic defect may coexist. Where bleeding is so acutely threatening as to require urgent intervention, diagnosis and treatment must proceed simultaneously. In the case of minor haemorrhage (not threatening to life or limb) it may be preferable to defer therapy while the nature of the bleeding disorder is methodically investigated. Initial laboratory evaluation is guided by the preliminary clinical impression. The amount of blood loss can be inferred from the haematocrit or haemoglobin concentration, and the platelet count will quickly identify cases in which thrombocytopenia is the likely cause of bleeding. In the latter instance, examination of the red cell morphology, leucocyte differential, and mean platelet volume may allow the aetiological mechanism to be presumptively identified as hypoproliferative or consumptive. With regard to coagulation testing, the activated PTT, prothrombin time, and thrombin time usually constitute an adequate battery of screening tests, unless the clinical picture is sufficiently distinctive to indicate the immediate need for more focused testing. In any event, sufficient blood should be taken to allow more detailed studies to be done based on the results of these screening tests. These results will direct the need for further assays, such as specific clotting factor activity levels, von Willebrand factor assays, tests for coagulation inhibitors, platelet function assays, and markers of primary or secondary fibrinolytic activity.     

A longitudinal prospective study of bleeding diathesis in Egyptian pediatric patients: single-center experience

Keeping an updated registry of bleeding disorders is crucial for planning care and documenting prevalence. We aimed to assess the prevalence of various bleeding disorders including rare inherited coagulation and platelet disorders concerning their clinico-epidemiological, diagnostic data and bleeding manifestations severity. Patients suffering from manifestations of bleeding or coagulation disorders presented to Hematology Clinic during 16 years were included and prospectively followed up. Demographics, clinical characteristics, complete blood count, bleeding, prothrombin and activated partial thromboplastin times, platelet aggregation tests and bone marrow aspiration were recorded. Overall 687 patients with bleeding disorders from total 2949 patients were identified. Inherited coagulation defects were found in 27.2%; hemophilia A (70.6%), hemophilia B (13.9%), factor I deficiency (2.3%), factor V deficiency (1.6%), factor X deficiency (4.2%), factor VII deficiency (2.6%), factor XIII deficiency (1.1%), combined factor deficiency (2.1%) and unclassified coagulation disorders in 1.6% of studied patients. Overall 72.7% had diagnosed with platelet disorders; immune thrombocytopenia was the commonest (74.8%), and inherited conditions represent (25.2%) in the following order: Glanzman's thrombasthenia (11.2%), von Willebrand disease (6.6%), Bernard-Soulier syndrome (1%) and Chediak Higashi in 0.4% and unclassified in 6%. Median age of diagnosis of coagulation and platelet disorders were 33 and 72 months. Presenting symptoms of coagulation disorders were: 25.1% post circumcision bleeding, 22.5% ecchymosis, 20.9% hemoarthrosis and 15% epistaxis. Symptoms of rare coagulation disorders were postcircumcision bleeding (20%), bleeding umbilical stump (20%), epistaxis (12%), hemoarthrosis (8%) and hematomas (4%). Presenting symptoms in rare inherited platelet disorders were purpura, ecchymosis, epistaxis and bleeding gums, respectively. Analysis of the clinico-epidemiological data of patients with bleeding disorders is a useful tool for monitoring and improving their quality of care.     

Perioperative monitoring of primary and secondary hemostasis in coronary artery bypass grafting

On-pump cardiac surgery is accompanied by complex alterations of hemostasis. The excessive postoperative bleeding has been attributed to acquired platelet dysfunction, impaired plasmatic coagulation, and increased fibrinolysis. The characterization of the hemostatic defects responsible for bleeding is crucial for specific treatment and optimal clinical management of the patient. For rapid determination of platelet-dependent primary hemostatic capacity (PHC), the Platelet Function Analyzer PFA-100 system is available. To evaluate the PFA performance in perioperative monitoring, a study was performed in 49 patients selected for low bleeding risk undergoing selective primary coronary artery bypass grafting (CABG). We compared PHC with Simplate bleeding time (BT) and platelet aggregometry. Furthermore, we analyzed global hemostasis by thromboelastography (TEG) and plasmatic coagulation by standard clotting tests prothrombin time (PT, Quick), activated partial thromboplastin time (aPTT), thrombin time (TT) and clotting factors and fibrinolysis by batroxobin (reptilase) time (RT). In all patients BT was postoperatively increased by 1.5- to 2-fold irrespective of perioperative complications and decreased to mildly prolonged values on the first postoperative day (1st day). In patients without complications, PHC in both collagen-adenosine diphosphate closure time (CADP-CT: 83 seconds preop, 78 seconds postop, and 74 seconds 1st day) and collagen-epinephrine closure time (CEPI-CT: 98 seconds preop, 95 seconds postop, 85 seconds 1st day) remained nearly stable. Apart from a patient with postoperative moderate thrombocytopenia, in bleeding patients no other significant defect of postoperative platelet hemostatic capacity was observed. However, on 1st day, the PHC of those patients was significantly reduced compared with non-bleeding patients. In patients with postoperative myocardial ischemia, increased PHC was identified by significantly shorter postoperative CADP-CT (66 seconds vs. 83 seconds) than in uncomplicated patients. By aggregometry, partial platelet dysfunction was observed in some patients without correlation to bleeding complications. In seven of 9 patients the postoperative bleeding complication was attributed to prolonged heparin anticoagulation and/or mildly enhanced fibrinogenolysis/fibrinolysis by TEG and standard plasmatic coagulation tests (TEG: k time 18 minutes vs. 8 minutes; aPTT: 47 seconds vs. 32 seconds; TT: 18.0 seconds vs. 12.3 seconds) and (RT: 19.5 seconds vs. 17.7 seconds). The impairment of PHC, platelet aggregation, and clotting factors observed on the 1st day in bleeding and in intra-aortic balloon pump (IABP) patients are most likely secondary effects, for example, loss of active platelets and clotting factors, to the primary postoperative bleeding or implantation of the IABP. In conclusion, our data indicate that in standard CABG procedures highly variable alterations of the hemostatic system occur after cardiopulmonary bypass (CPB) even in patients with assumed low operative risks. For identification of post-CPB bleeding complications, thromboelastography, aPTT, and TT and heparin and batroxobin (reptilase) time as fibrinolysis-sensitive assays are useful. Platelet function appears to be rapidly restored in uncomplicated CABG. PHC determination by PFA-100 demonstrates a high specificity for adequate platelet function and, therefore, could be beneficial in improved transfusion of platelet concentrates. PHC testing by PFA-100 may help identify postoperative platelet hyper-reactivity associated with myocardial lesion.     

Management of bleeding complications of hematologic malignancies

Persons with hematologic malignancies bleed for a variety of reasons, including alterations in platelet function and numbers, clotting factor deficiencies, circulating anticoagulants, and defects in vascular integrity. The management of bleeding begins with a full characterization of the hemostatic defect. Vitamin K deficiency always should be considered and excluded by clinical history and laboratory tests. Localized bleeding is treated by packing, topical hemostatic agents, dressings, vessel ligation, laser beam coagulation, or embolization. Platelet transfusions are administered for hemorrhage secondary to severe platelet dysfunction or thrombocytopenia, but usually are not indicated if there is no bleeding, even though platelets may be as low as 10,000/microL. Bleeding due to thrombocytopenia that is refractory to random-donor platelets may respond to cross-matched compatible platelets, or to recombinant factor VIIa (rFVIIa). Fresh frozen plasma is indicated infrequently; bleeding due to coagulopathies is better managed with cryoprecipitate if fibrinogen is low, or with clotting factor concentrates appropriate for the specific clotting factors found to be deficient. rFVIIa or activated prothrombin complex concentrate usually controls hemorrhage due to autoantibodies directed against factor VIII, and acquired von Willebrand's disease may be responsive to desmopressin or intravenous gamma globulin infusion. Antifibrinolytic agents often enhance other hemostatic therapies, but should be withheld if there is genitourinary bleeding or evidence of disseminated intravascular coagulation. Finally, plasmapheresis and immunoadsorption to remove paraproteins may be helpful when other measures fail to curb bleeding.     

Persistently Elevated Laboratory Markers of Thrombosis and Fibrinolysis After Clinical Recovery in Malaria Points to Residual and Smouldering Cellular Damage

Screening coagulation tests and assays for thrombosis and fibrinolysis were performed in 80 cases of malaria at presentation and during the course of the disease. Close correlation between the degree of thrombocytopenia (observed in >97% cases) and the presence hemorrhagic manifestations at presentation, and improvement in the platelet count in parallel with clinical recovery emphasised the role of platelets in the pathogenesis of coagulopathy in malaria. A potential selection bias resulting from inclusion of only patients admitted at a tertiary care hospital could explain the higher incidence (27.5%) of clinical bleeding observed in this study compared to that reported in the literature. Although a significant correlation between overt bleeding and abnormal PT/INR and APTT (observed in 20–37% cases) could not be demonstrated, a good correlation existed between normal screening coagulation tests and the absence of bleeding complications. Elevated D-Dimer and FDP levels in almost all cases (90%) of both types of malaria confirmed the high prevalence of disseminated intravascular coagulation and fibrinolysis. A correlation between rising D-Dimer levels and the incidence of bleeding was observed. Follow up studies in six cases with complications showed normalization of platelet counts and of screening coagulation assays with clinical recovery. D-Dimer and FDP levels however, remained elevated in most of these cases indicating the continuation of a smouldering coagulopathy even after full clinical recovery possibly due to the persistence of residual damage to the cells caused by the parasitic infection. Knowledge of this fact is important for avoiding unnecessary investigations and longer hospital stay in patients admitted with malaria.     

Interaction between nabumetone--a new non-steroidal anti-inflammatory drug--and the haemostatic system ex vivo

Twenty-six healthy volunteers were given the non-steroidal anti-inflammatory drug nabumetone (1 g/day p.o.) for 10 days. Platelet aggregation tests in response to adenosine diphosphate, adrenaline, collagen, arachidonic acid, and ristocetin and bleeding time and coagulation screening tests were performed on three occasions: (1) before drug therapy; (2) on the last day of drug therapy, and (3) 5 days after the end of therapy. No significant changes were noted in platelet aggregation, bleeding time, or the coagulation screening tests, except for a significant drop in fibrinogen during therapy and for 1 week after stopping the drug. The lack of any antiplatelet action and minimal effects on the coagulation parameters recommend the drug as a suitable antirheumatic in patients with bleeding disorders. The hypofibrinogenaemic action requires further studies.     

Coagulopathy in liver disease

Opinion statement The liver plays a central role in hemostasis, as it is the site of synthesis of clotting factors, coagulation inhibitors, and fibrinolytic proteins. The most common coagulation disturbances occurring in liver disease include thrombocytopenia and impaired humoral coagulation. Therapy’s overall goal is not to achieve complete correction of laboratory value abnormalities but to gain hemostasis. Therapy with vitamin K may be a useful option in patients with increased prothrombin time due to vitamin K deficiency; in patients with malnutrition; in patients using antibiotics; and in patients with cholestatic liver disease, particularly prior to invasive procedures. Infusion of fresh frozen plasma is more often effective and is recommended in patients with liver disease before invasive procedures or surgery, as such patients require transient correction in their prothrombin time. Therapy with plasma exchange may be considered in patients who cannot be treated with fresh frozen plasma due to volume overload risk. In patients with severe coagulopathy and hypofibrinogenemia, cryoprecipitate therapy is ideal. Therapy with prothrombin-complex concentrate is seldom pursued in patients with liver disease due to high risk of thrombotic complications. Transfusions of platelets are appropriate for patients with thrombocytopenia (< 50,000/mm³) associated with active bleeding or before invasive procedures in which a short-term platelet count increase is noted. Trial with desmopressin may be considered before invasive procedures in patients with liver disease and with refractory and prolonged bleeding time. Recombinant activated factor VIIa administration is suggested for patients with significantly prolonged prothrombin time and contraindications to fresh frozen plasma therapy; however, this is expensive. Thrombopoietin and interleukin-11 are currently investigational for patients with thrombocytopenia of chronic liver disease. Liver transplantation completely restores impaired coagulation abnormalities and is the ultimate intervention that corrects coagulopathy of advanced liver disease and liver failure.     

Treatment of drug-induced immune thrombocytopenias

Several therapeutic agents can cause thrombocytopenia by either immune-mediated or non-immune-mediated mechanisms. Non-immune-mediated thrombocytopenia is due to direct toxicity of drug molecules to platelets or megakaryocytes. Immune-mediated thrombocytopenia, on the other hand, involves the formation of antibodies that react to platelet-specific glycoprotein complexes, as in classic drug-induced immune thrombocytopenia (DITP), or to platelet factor 4, as in heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombotic thrombocytopenia (VITT). Clinical signs include a rapid drop in platelet count, bleeding or thrombosis. Since the patient''s condition can deteriorate rapidly, prompt diagnosis and management are critical. However, the necessary diagnostic tests are only available in specialized laboratories. Therefore, the most demanding step in treatment is to identify the agent responsible for thrombocytopenia, which often proves difficult because many patients are taking multiple medications and have comorbidities that can themselves also cause thrombocytopenia. While DITP is commonly associated with an increased risk of bleeding, HIT and VITT have a high mortality rate due to the high incidence of thromboembolic complications. A structured approach to drug-associated thrombocytopenia/thrombosis can lead to successful treatment and a lower mortality rate. In addition to describing the treatment of DITP, HIT, VITT, and vaccine-associated immune thrombocytopenia, this review also provides the pathophysiological and clinical information necessary for correct patient management.     

Evaluating platelet function disorders in children with bleeding tendency – A single center study

Platelet function disorders (PFDs) are a common cause of mild bleeding tendency. However, they cannot be recognized by standard screening studies. The gold standard test for PFD is platelet aggregation, performed by light transmission aggregometry (LTA). A newer and less validated method is the closure time (CT), performed by the platelet function Analyzer 100 (PFA-100). Data regarding the validity of these tests in children are limited. The aim of this study was to evaluate the usefulness of LTA and PFA-100 for the diagnosis of pediatric patients with bleeding tendency.

This retrospective study included patients one month–18 year old that had LTA tests performed at the coagulation laboratory of Rabin Medical Center between the years 2006–2015. Bleeding severity was assessed using a pediatric bleeding score. Patients were excluded from analysis if they had thrombocytopenia, thrombocytosis or coagulation factors deficiencies. One hundred and thirty-seven (137) patients were included in the analysis. The median age was 7.5 years (range one month–18 years). Most patients (93%) had a bleeding score of 2 or more. Abnormal LTA was found in 40% and prolonged CT in 23% of the patients. Abnormal LTA was significantly more common in patients with a bleeding score of 2 or more compared to patients with a lower bleeding scores (P = 0.04). No significant correlation was found between the bleeding severity and the number of agonists which induced abnormal responses (p = 0.52) or the CT (p = 0.35). Furthermore, no correlation was found between abnormal LTA and prolonged CT.

To conclude, we were able to diagnose 40% of children who presented with bleeding tendency with platelet aggregation defects by LTA. Abnormal LTA was significantly more prevalent in patients with a bleeding score of 2 and above. In contrast, CT was not found to be sensitive as a screening tool for PFD. Therefore, our data extend the validity of the use of LTA for the evaluation of pediatric patients with bleeding tendency.     

Thrombocytopenia and bleeding in dental procedures of patients with Gaucher disease

Summary. The risk of bleeding during dental procedures may be increased in patients with Gaucher disease. We aimed to evaluate potential coagulation and platelet function abnormalities and targeted therapy accordingly. Patients with type 1 Gaucher disease who were treated at the Oral and Maxilo‐Facial surgery clinic at Sheba Medical Center between 2003 and 2010 comprised the study cohort. Data collected included disease history, enzyme treatment, platelet counts, dental therapy and outcome. Bleeding was defined as excessive bleeding during or immediately following procedure. Coagulation studies and platelet function tests including aggregometry were performed on all patients. Dental procedures (n = 14, including eight teeth extractions, two crown lengthening procedures, one cyst enucleation and three deep dental scaling) of seven patients were studied. Mean platelet count prior to procedure was 73 K ± 14.8 mm³. Patients bleeding risk score was calculated according to previous history of bleeding tendency, degree of thrombocytopenia, presence of comorbid coagulopathy and the type of dental procedure. Two patients with highest risk score received prophylactic platelet transfusions, three patients (medium‐risk) received DDAVP preprocedure and all received systemic tranexamic acid, which was the only systemic therapy for low‐risk patients. Meticulous surgical local haemostasis was applied. No excessive intra‐operative or postoperative bleeding occurred. Patients with Gaucher disease who have thrombocytopenia and abnormal platelet function tests may be safely treated if meticulous haemostasis is applied along with systemic therapy as required. Platelet transfusions are not mandatory and should be applied considering the procedure‐related risk and the patient’s calculated haematological risk for bleeding.     

Hemostasis Testing during Massive Blood Replacement A Study of 172 Cases

Abstract. A 24-hour service was organized to study changes in the hemostatic system in surgical patients undergoing massive transfusion for excessive bleeding during operation or in the early postoperative period. Hemostasis tests gave normal results in only 12 (7%) of the 172 patients, while in the remaining 160 (93%) one or more tests gave abnormal results. The platelet count was the most frequently abnormal, followed by the prothrombin time and plasma fibrinogen. Well-defined hemostatic disorders (such as DIC, heparinization and liver disease) were ascertained in 82 patients (48%). 78 patients (45%) had less specific laboratory abnormalities, with a particularly high incidence of thrombocytopenia and less pronounced alterations in the coagulation tests. Unlike the patients with defined disorders, the strong inverse correlation in this group between platelet count, prothrombin time, plasma fibrinogen, and the number of transfusions suggests that the laboratory abnormalities were induced by massive blood replacement. Standard schemas involving the administration of platelet concentrates and/or fresh-frozen plasma without evaluation of hemostasis did not help to reduce the incidence of abnormalities. These measures also failed to decrease the requirements for whole blood and/or packed red cells. Therefore, indiscriminate administration in the massively transfused postoperative patient of blood components based on preestablished schemes appears to be unjustified. An approach based on hemostasis screening, identification of the underlying disorder, directed therapeutic intervention and laboratory monitoring is likely to be more effective.     

Hemostasis in liver transplantation:Pathophysiology,monitoring, and treatment

Recent findings in the pathophysiology and monitoring of hemostasis in patients with end stage liver disease have major impact on coagulation management during liver transplantation. There is increasing evidence, that the changes in both coagulation factors and platelet count regularly observed in patients with liver cirrhosis cannot be interpreted as a reliable indicator of diffuse bleeding risk. Instead, a differentiated view on hemostasis has led to the concept of a rebalanced coagulation system: While it is important to recognize that procoagulant factors are reduced in liver cirrhosis, it is also evident that synthesis of anticoagulant factors and fibrinolytic proteins produced in the liver is also diminished. Similarly, the decreased platelet count may be counterbalanced by increased platelet aggregability caused by highly active von Willebrand multimeres. The coagulation system is therefor stated to be rebalanced. While under normal "unstressed" conditions diffuse bleeding is rarely observed, however both diffuse bleeding or thrombus formation may occur when compensation mechanisms are exhausted. While most patients presenting for liver transplantation have severe cirrhosis, liver function and thus production of pro- and anticoagulant factors can be preserved especially in cholestatic liver disease. During liver transplantation, profound changes in the hemostasis system can occur. Surgical bleeding can lead to diffuse bleeding as coagulation factors and platelets are already reduced. Ischemia and tissue trauma can lead to alterations of hemostasis comparable to trauma induced coagulopathy. A further common disturbance often starting with the reperfusion of the transplanted organ is hyperfibrinolysis which can eventually precipitate complete consumption of fibrinogen and an endogenous heparinization by glycocalyx shedding. Moreover, thrombotic events inliver transplantations are not uncommon and contribute to increased mortality. Besides conventional laboratory methods, bed-side monitoring of hemostasis(e.g., thrombelastography, thrombelastometry) is often used during liver transplantation to rapidly diagnose decreases in fibrinogen and platelet count as well as hyperfibrinolysis and to guide treatment with blood products, factor concentrates, and antifibrinolytics. There is also evidence which suggests when algorithms based on bed-side hemostasis monitoring are used a reduction of blood loss, blood product use, and eventual mortality are possible. Notably, the bed-side monitoring of anticoagulant pathways and the thrombotic risk is not possible at time and thus a cautious and restrictive use of blood products is recommended.     

Screening coagulation tests and clotting factors in homozygous beta-thalassemia.

In 30 children with homozygous beta-thalassemia the hemostasis screening tests (bleeding time, PT, PTT), platelet count and specific assays of clotting factors were carried out 25 days after their last transfusion. PT, PTT, and bleeding time showed minor variations; considerable thrombocytosis was found in splenectomized patients. Factors IX and XII were decreased in a high proportion of patients, the vitamin K-dependent factors (II, VII, IX, X) were slightly reduced and factors I, V and VIII remained within the normal range in a majority of patients. Hepatic failure resulting in defective protein synthesis does not explain the more marked impairment of factors XI and XII, which might be secondary to activation of the intrinsic coagulation and/or kallikrein systems following intravascular haemolysis and multiple blood transfusions.     

The myelodysplastic syndromes--a study of haemostatic function and platelet ultrastructure

The myelodysplastic syndromes (MDS) are characterised by dysplastic marrow and cytopenia. Clinically detectable bleeding is uncommon and usually attributed to thrombocytopenia. We have investigated some aspects of haemostatic function in 17 patients with MDS and compared the results with findings from 17 control patients matched for age and sex. No specific disorder of blood coagulation or fibrinolysis was identified. The main abnormalities observed in the patients were: prolongation of the bleeding time which was greater than could be explained on the basis of thrombocytopenia in 13 patients; absent, or severely impaired platelet aggregation in response to collagen in 7 patients; impaired platelet production of malondialydehyde when stimulated with collagen and abnormal release of 14C-5 hydroxytryptamine in 5 patients; and abnormalities of ultrastructure in all 5 patients whose platelets were viewed by electron microscopy.     

Idiopathic thrombocytopenic purpura complicated with circulating lupus anticoagulant

A 37 year-old female was admitted to our hospital because of hypermenorrhea, prolonged bleeding time, thrombocytopenia and the diagnosis of idiopathic thrombocytopenic purpura (ITP) was made. Though activated partial thromboplastin time (APTT) was markedly prolonged, her coagulation factors were within normal ranges. Activities of the circulating lupus anticoagulant (LAC) was suggested. Kaolin clotting time of the platelet poor plasma was used as a sensitive screening test using the mixture of normal and patient's plasma for the detect of LAC. As a result, LAC positive pattern was observed. The treatment with high-dose gammaglobulin brought out a transient increase of the platelet count, but the prolongation of APTT was not corrected. Both the platelet count and the prolongation of APTT were significantly improved after the treatment with betamethasone.     

The myelodysplastic syndromes - A study of haemostatic function and platelet ultrastructure

The myelodysplastic syndromes (MDS) are characterised by dysplastic marrow and cytopenia. Clinically detectable bleeding is uncommon and usually attributed to thrombocytopenia. We have investigated some aspects of haemostatic function in 17 patients with MDS and compared the results with findings from 17 control patients matched for age and sex. No specific disorder of blood coagulation or fibrinolysis was identified. The main abnormalities observed in the patients were: prolongation of the bleeding time which was greater than could be explained on the basis of thrombocytopenia in 13 patients; absent, or severely impaired platelet aggregation in response to collagen in 7 patients; impaired platelet production of malondialydehyde when stimulated with collagen and abnormal release of ¹⁴C-5 hydroxytryptamine in 5 patients; and abnormalities of ultrastructure in all 5 patients whose platelets were viewed by electron microscopy.     

Thromboelastography identifies children with rare bleeding disorders and predicts bleeding phenotype

Rare bleeding disorders (RBDs) comprise 3–5% of all congenital bleeding disorders. They can evade typical coagulation screening tests and there is a poor correlation between laboratory results and bleeding phenotype. Thromboelastography (TEG) measures coagulation globally in whole blood samples. The aims of this study were to evaluate the utility of TEG as an adjunct to the routine screening tests employed for the diagnosis of RBDs and to correlate TEG results with the bleeding phenotype in RBDs. TEG parameters and clot kinetics were compared to bleeding phenotypes (asymptomatic, mild, moderate and severe) in 26 RBD patients and 30 normal controls. Clot kinetics correlated strongly with RBDs and with the severity of bleeding phenotype with mean maximum rate of thrombus generation (MRTG) 15.4 mm min^?1 in controls vs. 6.0 in RBDs (P < 0.0001, Wilcoxin). The mean MRTG was 7.7 in mildly symptomatic, 5.5 in moderately symptomatic and 4.1 in severely symptomatic patients (P < 0.0001, Kruskal–Wallis). Disorders that are often missed by conventional screening tests, dysfibrinogenaemia and platelet disorders displayed a distinctive TEG curve with markedly decreased maximum amplitude (MA) and low MRTG values. Factor XIII and PAI deficient patients displayed increased fibrinolysis in addition to low MRTGs. All patients with RBDs, but none of the normal controls, had abnormal clot kinetics suggesting that TEG may be an effective screening test for RBDs.