Hemostatic disorders in patients with infective endocarditis undergoing urgent surgical valve replacement - Rethinking current beliefs.

BACKGROUND: Although infective endocarditis (IE) represents a unique model of thrombo-inflammatory disease, the most frequent early complications of surgical valve replacement (SVR) in IE population are coagulopathy and bleeding. The hemostatic capacity and procedure-related coagulation disorders of IE patients undergoing SVR are unknown. The aims of this study were to test periprocedural hemostasis in IE patients undergoing urgent SVR, and to assess the association between disorders of hemostasis and early bleeding as well as with thromboembolic events. METHODS: A prospective, two-center, hypothesis generating, observational study was performed between Dec 2017 and Jan 2020. Periprocedural hemostasis of IE patients was assessed using Total Thrombus-formation Analysis System (T-TAS Plus) within 24 h before and 72 h post SVR. RESULTS: Overall, 25 patients with active IE undergoing urgent SVR were tested. Hemostatic capacity of IE patients was significantly impaired pre-SVR as well as post-SVR compared to normal values, in most aspects of T-TAS assays under high and low shear forces, including prolonged activation of coagulation (T10), final clot formation (OT) and clot strength (AUC30). Post-SVR T-TAS results were significantly associated with early bleeding and with red blood cell, platelet, and fresh frozen plasma administration. No association with thrombo-embolic events was found. CONCLUSIONS: Patients with active IE undergoing urgent SVR have significantly reduced hemostatic capacity before and after SVR. Hemostatic insufficiency post-SVR is related to bleeding and blood products transfusion. T-TAS may be helpful in assessment of periprocedural hemostasis in patients with IE undergoing SVR.

Recent advances in therapeutic options for rare hemostatic disorders: selected poster extracts of recent research in hemophilia A, congenital hemophilia with inhibitors, von Willebrand disease, and thrombotic thrombocytopenic purpura presented at the 29th congress of the International Society on Thrombosis and Haemostasis (ISTH 2021, Jul 17-21; virtual congress).

Hemophilia, von Willebrand disease (VWD), and thrombotic thrombocytopenic purpura (TTP) are rare diseases affecting normal hemostasis. Although they differ in their pathogenesis and clinical manifestation, if left undiagnosed and untreated, all these conditions can result in severe long-term consequences and can be potentially life-threatening. This article summarizes a poster series funded by Takeda and presented virtually at the 29th annual congress of the International Society on Thrombosis and Haemostasis (ISTH) in 2021: Data from real-world evidence highlight the importance of joint health and personalized prophylaxis to prevent bleeding for patients with hemophilia, the need to further raise disease awareness in support of timely diagnosis and access to treatment in general practice settings for patients with VWD, and describe the clinical burden for patients with TTP and the importance to advance treatment options for these patients.

Thrombodynamics as a tool for monitoring hemostatic disorders in patients with chronic glomerulonephritis complicated by nephrotic syndrome.

Nephrotic syndrome (NS) is associated with a high risk for venous and arterial thrombosis due to hypercoagulability. Integral tests designed to assess hemostasis can become an alternative for measuring hypercoagulability in patients with NS. STUDY OBJECTIVE: To assess hemostatic disorders in CGN patients complicated by NS using the thrombodynamics test. MATERIALS AND METHODS: The study included 60 adult patients with chronic glomerulonephritis (CGN), mean age 37 years, 31 (52%) women, and 29 (48%) men. Among all patients, 53 % of patients had NS, 47 % had no sign of NS. Hemostasis was assessed using the thrombodynamics test. The results were compared with biochemical parameters, which are usually associated with NS and renal dysfunction. RESULTS: According to the thrombodynamics test, CGN patients with NS demonstrated a tendency to hypercoagulability: increased rates of V (rate of clot growth), increased D (clot density), and increased CS (clot size) after 30 minutes. A positive correlation of these parameters with the serum albumin, creatinine levels, and glomerular filtration rate (GFR) indicates the influence of severe NS and renal dysfunction on the hemostasis activation in CGN patients with NS. CONCLUSION: According to the thrombodynamics test, CGN patients with NS demonstrate increased rates of clot formation, increased clot size after 30 minutes, and increased clot density due to secondary hemostasis activation. These changes positively correlate with the severity of hypoalbuminemia, hypercholesterolemia, and renal dysfunction in NS patients.

Alteraciones hemostáticas provocadas por el veneno de la culebra mapanare (Porthidium lansbergii hutmanni) en pacientes venezolanos / Haemostatic alterations caused by the venom of Lansberg's hognosed pitviper (Porthidium lansbergii hutmanni) in Venezuelan patients

Objective: to describe the haemostatic characteristics of the venom as well as the potency appraisal of the polyvalent antiophidic serum against haemotoxicity from Porthidium lansbergii hutmani experimental envenomation. Methods: Evaluation was performed of the venom's lethality, haemorrhagic activity, effects on coagulation and platelet aggregation, proteolytic activity, and neutralization by the commercial antivenom available in the country. Results: Several components with haemostatic activities were found in Porthidium l. hutmanni venom when a study of fibrinogenolytic, haemorrhagic and proteolytic activities was conducted of a pool of P.l.h venom. Porthidium l. hutmanni venom lacked the coagulant and defibrinating activities that are characteristic of bothropic venoms. Porthidium l. hutmanni venom showed very high haemorrhagic and anticoagulant activities. These findings could be related to the presence of multiple metalloproteases, which was evidenced in this study, and also the possible presence of phospholipases or other anticoagulant activity proteins that were not defined here. They inhibited platelet aggregation, suggesting that the venom had some proteins with marked effects on haemostasis. The commercial antivenom proved to be of little effectiveness in neutralizing the crude venom haemorrhagic activity. Conclusions: These toxins cause many physiopathological alterations in bitten patients, creating a clinical picture characterized by oedema, local and systemic haemorrhages, and even necrosis, comparable to that seen in bothropic envenomation. Porthidium l. hutmanni venom has no in vitro procoagulant activity, typical of bothropic venoms, suggesting there are variances in its protein conformation. Porthidium l. hutmanni venom is used for horse immunization. However, in order to preserve the patient's life, it is necessary to improve the immunization process to produce antivenom containing high avidity and specificity antibodies against the major toxins present in this venom. Porthidium l. hutmanni venom has demonstrated being a venom with high lethal, haemorrhagic, proteolytic and procoagulant activities, whose description will have enormous utility among clinicians who deal with these accidents in its geographical distribution areas(AU)

Objetivo: Describir las características hemostáticas del veneno y evaluar la potencia del suero polivalente antiofídico contra la hemotoxicidad provocada por el envenenamiento experimental por Porthidium lansbergii hutmanni. Métodos: Se realizó una evaluación de la letalidad, actividad hemorrágica, efectos en la coagulación y agregación plaquetaria, actividad proteolítica y neutralización por el antiveneno disponible comercialmente en el país. Resultados: Se encontraron varios componentes con actividad hemostática en el veneno de Porthidium l. hutmanni al realizarse un estudio de la actividad fibrinogenolítica, hemorrágica y proteolítica de una muestra de veneno de Porthidium l. hutmanni. El veneno de Porthidium l. hutmanni no mostró la actividad coagulante o defibrinante característica de los venenos botrópicos. El veneno de Porthidium l. hutmanni mostró una elevada actividad hemorrágica y anticoagulante. Estos resultados podrían estar relacionados con la presencia de múltiples metaloproteasas, la que quedó demostrado en el estudio, y también a la posible presencia de fosfolipasas u otras proteínas de actividad anticoagulante que no se definen en el mismo. La inhibición de la agregación plaquetaria sugiere que el veneno contiene algunas proteínas con un marcado efecto sobre la hemostasis. El antiveneno comercial mostró poca efectividad en la neutralización de la actividad hemorrágica del veneno crudo. Conclusiones: Estas toxinas provocan muchas alteraciones fisiopatológicas en las víctimas de mordeduras, creando un cuadro clínico caracterizado por edema, hemorragias locales y sistémicas e incluso necrosis comparable con la que ocurre en el envenenamiento botrópico. El veneno de Porthidium l. hutmanni no tiene la actividad procoagulante in vitro típica de los venenos botrópicos, lo que apunta a variaciones en su conformación proteica. El veneno de Porthidium l. hutmanni de utiliza en la inmunización de los caballos. Sin embargo, para preservar la vida del paciente, es necesario mejorar el proceso de inmunización con vistas a producir un antiveneno que contenga anticuerpos de elevada avidez y especificidad contra las principales toxinas presentes en el veneno. El veneno de Porthidium l. hutmanni ha mostrado ser un veneno de elevada actividad letal, hemorrágica, proteolítica y procoagulante, cuya descripción tendrá una enorme utilidad para los médicos que atienden esos accidentes en sus áreas de distribución geográfica(AU)

The Associations between Central Nervous System Diseases and Haemostatic Disorders.

The aim of this review was to examine the relationship between the occurrence of central nervous system (CNS) diseases, the medicines used in their treatment and the blood coagulation process. The paper mainly focuses on the effects of antidepressant and antipsychotic drugs. Special attention has been paid to the influence of drugs on platelets, the vascular endothelium, plasma coagulation and fibrinolysis, regarding coagulation.

Occult cancer detection in patients with hemostatic disorder and venous thromboembolism.

There are physiologic ties between Von Willebrand Factor (VWF) and circulating tumor cells. VWF appears to play a role in tumor biology, but it is unclear whether cancer behavior differs in Von Willebrand Disease. In patients presenting with venous thromboembolism (VTE), occult cancer is frequently considered as an underlying cause. The prevalence of occult cancer after provoked VTE is low (3%); therefore, cancer screening in these patients is not routinely recommended. In those with unprovoked VTE, occult cancer is more prevalent, estimated between 4 and 10%. Due to this elevated risk, occult cancer screening is recommended in this population. Multiple studies have investigated whether a "limited" approach (including history and physical exam, basic labs, and chest X-ray) versus "extensive" approach (addition of advanced imaging, such as computer tomography) is more effective. Current data fails to demonstrate extensive screening strategies diagnose more occult cancer, miss fewer cancers during follow up, or improve cancer-related mortality. Furthermore, many patients may be needlessly exposed to unnecessary diagnostic procedures with their associated complications and costs, as well as significant anxiety. Therefore, the decision to perform additional testing should be made on a case-by-case basis. Additional studies are needed to identify subgroups of patients with unprovoked VTE at highest risk for occult cancer.

Management of Hemostatic Disorders in Patients With Advanced Liver Disease Admitted to an Intensive Care Unit.

Patients with liver diseases frequently acquire complex changes in their hemostatic system. Traditionally, bleeding complications in patients with liver disease were ascribed to these hemostatic changes, and liver diseases were considered as an acquired bleeding disorder. Nowadays, it is increasingly acknowledged that patients with liver diseases are in "hemostatic rebalance" due to a commensurate decline in pro- and anticoagulant drivers. Indeed, both thrombosis and bleeding may complicate liver disease. Such complications may be particularly worrisome in critically ill patients with liver disease. This review will outline knowns and unknowns in prediction, prevention, and treatment of bleeding and thrombosis in patients with liver disease admitted to an intensive care unit.

Characteristics of provoked deep venous thrombosis in a tertiary care center.

OBJECTIVE: Provoked deep venous thrombosis (DVT) is precipitated by a specific event. This paper compares the characteristics of provoked DVT in patients with transient risk (TR) factors and patients with continuous risk (CR) factors. METHODS: A retrospective review of records of all consecutive patients diagnosed with DVT between January 2013 and August 2014 was performed. Patients with provoked DVT were included in the TR group if the provoking event resolved in 2 weeks and they did not have ongoing risk of thrombosis. Patients in the CR group had a provoked DVT with ongoing risk of thrombosis due to individual factors deemed to be ongoing risks of thrombosis, such as cancer, hypercoagulable disorder, and prolonged immobilization. Demographics, risk factors, association with pulmonary embolism (PE) and its severity, risk of recurrent venous thromboembolism (VTE), and mortality were compared between the two groups. RESULTS: A total of 838 patients were diagnosed with DVT, and 50.7% (425) were provoked. There were 127 (29.9%) patients with TR and 298 (70.1%) with CR. TR patients were younger (60.4 ± 16.3 vs 65.9 ± 16.0; P = .001). TR was more likely to be provoked by surgery (70.9% vs 55.4%; P = .003), whereas CR was more likely to be provoked by immobilization (21.5% vs 12.6%; P = .032). CR patients were affected by cancer (48.7%) and hypercoagulable disorders (4.4%). TR patients were more likely to have calf DVTs (36.2% vs 26.2%; P = .047). There was a trend toward lower association with PE on presentation in TR (17.3% vs 21.1%; P = .072), but that did not reach statistical significance. However, TR factors were more likely to be associated with low-risk PE compared with CR factors (30.2% vs 54.6%; P = .040). After mean follow-up of 7.2 months, CR had higher risk of recurrent VTE (14.0% vs 6.8%; P = .045) and mortality (23.5% vs 7.1%; P < .0001). CONCLUSIONS: Provoked DVT with CR factors affects older patients and is associated with high recurrence of VTE and mortality compared with provoked DVT with TR factors.

Recognition and Management of Hemostatic Disorders in Critically Ill Patients Needing to Undergo an Invasive Procedure.

Abnormal laboratory coagulation test results are frequently documented in critically ill patients, and these patients often also need to undergo invasive procedures. Clinicians have an understandable desire to minimize any perceived heightened risk of bleeding complications in those patients who require invasive procedures. In this setting, prophylactic administration of platelets or plasma is commonplace. This review explores the nature of these sequential statements and the degree to which these statements are supported by evidence. We discuss the complexity of managing the low risk of procedure-related bleeding in a setting where coagulation tests fail to reliably predict this risk. The role of prophylactic transfusion of platelets and plasma and correction of medication-induced coagulopathy is also reviewed. New strategies are required to improve the evidence base, including novel methodological approaches or the use of a clinical scoring system.

Neonatal Hemostatic Disorders: Issues and Challenges.

Neonates form a unique cohort with distinct features associated with the hemostatic system compared with older children and adults. The development of the human hemostatic system begins around 10 weeks in utero and continues to evolve during childhood. This dynamic period termed developmental hemostasis should be taken into consideration when diagnosing a neonate with disorders of bleeding or thrombosis.

Our experience with pre-operative haemostatic assessment of paediatric patients undergoing adenotonsillectomy at Federal Medical Centre, Makurdi.

BACKGROUND: In 2-4% of all patients requiring adenoidectomy, tonsillectomy or adenotonsillectomy, pre-operative screening tests for coagulation disorders are indicated to detect surgical bleeding complications. However, because of cost effect on the patients, the usefulness of these tests is being challenged. We therefore highlight our experience in paediatric patients undergoing adenoidectomy, tonsillectomy or both in our centre. PATIENTS AND METHODS: This is a 3½-year analysis of the data of 165 paediatric patients who had adenoidectomy, tonsillectomy or both over the study period. The data collected included age, sex, procedure done and detailed clinical bleeding history. RESULTS: A total of 165 children had either adenoidectomy or tonsillectomy, or both. There were 76 males and 89 females giving a male to female ratio of 1:1.2. Their ages ranged from 10 months to 18 years. Eighty-five (51.5%) patients had adenotonsillectomy, 48 (29.1%) and 32 (19.4%) had only tonsillectomies and adenoidectomies, respectively. Only 11 (6.7%) families volunteered the history of either prolonged bleeding with minor injury on the skin or occasional slight nose bleeding. Six (3.6%) patients including 3 of the children with positive family history had posttonsillectomy bleed, out of which 4 (66.7%) were moderate whereas the remaining 2 (33.3%) were severe bleeding, which was not statistically significant (P = 0.041). The two cases of severe bleeding had fresh whole blood transfused whereas the rest that had no bleeding issues were discharged home 48 h postoperatively. CONCLUSION: Our experience in this study suggests that detailed bleeding history is necessary as well as pre-operative haemostatic assessment, if available and affordable for paediatric patients undergoing adenotonsillectomy.

Asparaginase-associated concurrence of hyperlipidemia, hyperglobulinemia, and thrombocytosis was successfully treated by centrifuge/membrane hybrid double-filtration plasmapheresis.

Asparaginase-associated concurrence of hyperlipidemia, hyperglobulinemia, and thrombocytosis is a rare complication requiring aggressive lipoprotein apheresis, but no one of currently available lipoprotein apheresis methods can simultaneously resolve the 3 abnormalities. Herein, we reported a construction of double-filtration plasmapheresis (DFPP) using a combination of centrifugal/membranous plasma separation techniques to successfully treat a patient with hyperlipidemia, hyperglobulinemia, and thrombocytosis. A male presented with severe hyperlipidemia, hyperglobulinemia, and thrombocytosis during asparaginase treatment for NK/T-cell lymphoblastic lymphoma and was scheduled to receive lipoprotein apheresis. To simultaneously remove lipoproteins, immunoglobulin, and deplete platelets from blood, a centrifuge/membrane hybrid DFPP was constructed as following steps: plasma and part of platelets were separated first from whole blood by centrifugal technique and then divided by a fraction plasma separator into 2 parts: platelets and plasma components with large size, which were discarded; and those containing albumin, which were returned to blood with a supplement of extrinsic albumin solution. DFPP lasted 240 minutes uneventfully, processing 5450-mL plasma. The concentrations of plasma components before DFPP were as follows: triglycerides 38.22 mmol/L, total cholesterols 22.98 mmol/L, immunoglobulin A (IgA) 15.7 g/L, IgG 12.7 g/L, and IgM 14.3 g/L; whereas after treatment were 5.69 mmol/L, 2.38 mmol/L, 2.5 g/L, 7.7 g/L, and 0.4 g/L, respectively. The respective reduction ratio was 85.1%, 89.6%, 83.9%, 39.4%, and 96.9%. Platelet count decreased by 40.4% (from 612 × 10(9)/L to 365 × 10(9)/L). Centrifuge/membrane hybrid DFPP can simultaneously remove lipoproteins, immunoglobulin, and deplete platelets, with a success in treatment of asparaginase treatment-induced hyperlipidemia, hyperglobulinemia, and thrombocytosis, and may be useful for patients requiring DFPP but with particular situations.

Neonatal haemostasis. Impact on bleeding and thrombosis.

The maturation and postnatal development of the human coagulation system results in significant and important differences in the coagulation and fibrinolysis of neonates and young children compared to older children and adults. Importantly, these differences, which mostly reflect the immaturity of the neonatal haemostasis system, are functionally balanced. Healthy neonates show no signs of easy bruising or other bleeding diathesis and no increased tendency to thrombosis for any given stimulus compared to adults. Systemic diseases may affect haemostasis, thus predisposing ill neonates to increased risk for haemorrhagic or thrombotic complications. In hospitalized children, neonates have increased risk of developing thrombosis compared to infants and children, mostly associated with the presence of central venous catheter. For diagnosis of haemostasis disorders, diagnostic laboratories processing pediatric samples should use age, analyzer and reagent appropriate reference ranges. Age specific guidelines should be followed for the management of neonates with hemostatic disorders.

[The characteristics of function of endothelium in premature neonates with respiratory distress-syndrome].

The examined sampling consisted of 637 premature neonates in early neonatal period at 1-3 and 5-8 days of life. The analysis was applied to indices characterizing epithelium condition and regulating its function. It is noted that in premature neonates with respiratory distress-syndrome of derangement of regulation of function of endothelium are accompanied by increasing of hemostatic disorders and is characterized by increasing of thrombogenic and adhesive characteristics, decreasing of levels of VEGF, higher content of nitric oxide in the form of nitrites, cytokinemia and activation of complement systems.

Prevalence of hemostatic disorders in adolescents with abnormal uterine bleeding.

STUDY OBJECTIVE: To evaluate the incidence of hemostatic disorders in a population of adolescents with various patterns of abnormal uterine bleeding (AUB). DESIGN: Retrospective observational study. SETTING: University hospital. PARTICIPANTS: One hundred thirteen adolescents with AUB; mean age at menarche and mean age at the onset of symptoms 12 ± 1.2 years and 13.5 ± 2.8 years, respectively. MAIN OUTCOME MEASURES: Data on menstrual history, bleeding symptoms, co-existing medical conditions, and medical therapies were assessed. All patients were screened for hemostatic disorders with laboratory testing. The incidence of the disorders was calculated. Subjects were further divided in 2 groups based on whether the AUB started in the first 2 years from menarche (group 1) or later (group 2). A statistical analysis was performed using a chi-square test to compare incidence of hemostatic disorders between the groups. RESULTS: One hundred thirteen adolescents with AUB were identified. Overall, 54 (47.8%) patients had some underlying hemostatic disorder, of which a platelet dysfunction was the most common (17.7%). Von Willebrand disease was detected in 13.3% of cases and a deficiency of a coagulation factor in 12.4%. In 7.1% of patients an isolated increase of bleeding time was observed. When divided in 2 groups, 44.2% of patients in group 1 and 59.2% in group 2 had a coagulation disorders, with no statistically significant difference between the 2 groups (P = .17). CONCLUSION: AUB in adolescents is frequently associated with an underlying disorder of hemostasis, most commonly a platelet function disorder. The results highlight the importance of screening for coagulation disorders in adolescents with AUB, independently from the gynecologic age at onset.

The conundrum of neonatal coagulopathy.

The maturation and postnatal development of the human coagulation system was first studied and described more than 20 years ago. These older studies, supported by more recent data, confirm the significant and important differences in the physiology of coagulation and fibrinolysis in neonates and young children compared with older children and adults. Subsequently, significant differences were also described in the physiology of primary hemostasis and in global in vitro tests for hemostasis. These differences, which mostly reflect the immaturity of the neonatal hemostasis system, are functionally balanced. Healthy neonates show no signs of easy bruising or other bleeding diathesis and no increased tendency to thrombosis for any given stimulus compared with adults. Systemic diseases may affect hemostasis, predisposing ill neonates to increased hemorrhagic or thrombotic complications. The immaturity of the hemostasis system in preterm and very-low-birth-weight neonates may contribute to a higher risk for intraventricular hemorrhage. Therapies targeting the hemostasis system can be effective for preventing and treating these events. The concept of "neonatal coagulopathy" has an important impact on both the diagnosis and management of hemorrhagic or thrombotic events in neonates. For diagnosis of hemostasis disorders, diagnostic laboratories processing pediatric samples should use age-, analyzer-, and reagent-appropriate reference ranges. Age-specific guidelines should be followed for the management of neonates with hemostatic disorders.

Haemostatic alterations in a group of canine cancer patients are associated with cancer type and disease progression.

BACKGROUND: Haemostatic alterations are commonly detected in human and canine cancer patients. Previous studies have described haemostatic dysfunction in canine patients with haemangiosarcomas and carcinomas, and haemostasis has been assessed in dogs with various malignant and benign neoplasias. Few studies have addressed the effect of cancer type and progression of disease on the presence of haemostatic alterations in canine patients. The objective of the present study was to evaluate haemostatic variables of coagulation and fibrinolysis in a group of canine cancer patients, and to compare haemostatic changes to the cancer type and progression of disease. METHODS: The study population consisted of 71 dogs with malignant neoplasia presented to the University Hospital for Companion Animals, Faculty of Life Sciences, University of Copenhagen, Denmark. The study was designed as a prospective observational study evaluating the haemostatic function in canine cancer patients stratified according to type of cancer disease and disease progression. The coagulation response was evaluated by thromboelastrography (TEG), platelet count, activated partial thromboplastin time (aPTT), prothombin time (PT), fibrinogen and antithrombin (AT); and fibrinolysis by d-dimer and plasminogen. RESULTS: Hypercoagulability was the most common haemostatic dysfunction found. Non mammary carcinomas had increased clot strength (TEG G), aPTT and fibrinogen compared to the other groups. When stratifying the patients according to disease progression dogs with distant metastatic disease exhibited significantly increased fibrinogen, and d-dimer compared to dogs with local invasive and local non-invasive cancers. CONCLUSION: Hypercoagulability was confirmed as the most common haemostatic abnormality in canine cancer patients and haemostatic dysfunction in canine cancer patients was found related to the cancer type and progression of disease. Increase in TEG G, aPTT and fibrinogen were observed in non-mammary carcinomas and were speculated to overall represent a proinflammatory response associated with the disease. Dogs with distant metastatic disease exhibited increased fibrinogen and d-dimer. Future studies are needed to elucidate the clinical importance of these results.

[Algorithm of emergency diagnostics of acute bleedings caused by disturbed hemostasis in surgical practice].

On the basis of clinical experience the author substantiates the algorithm of clinico-laboratory emergency diagnostics and differential diagnostics of acute bleedings caused by disturbances of the primary and secondary hemostasis.

The bleeding child. Part I: primary hemostatic disorders.

Mucocutaneous bleeding is common in childhood and may be the result of primary hemostatic disorders such as vascular abnormalities, von Willebrand disease, thrombocytopenia, and platelet dysfunction. A detailed bleeding history and physical examination are essential to distinguish between normal and abnormal bleeding and to decide whether it is necessary to perform further laboratory evaluation. Initial laboratory tests include complete blood count, peripheral blood smear, mean platelet volume, von Willebrand factor (VWF) antigen assay, VWF ristocetin cofactor activity, and factor VIII activity. Once thrombocytopenia and von Willebrand disease have been excluded, platelet function should be tested by platelet aggregation. Additional specific diagnostic tests, such as platelet secretion tests and flow cytometry for the detection of platelet surface glycoprotein expression, are needed to confirm the raised hypothesis.