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A 65-year-old man experienced sudden onset of abdominal pain while working on his farm without significant trauma. He heard a ‘pop’ sound, followed by abdominal pain, lightheadedness and diaphoresis. He has a history of polycythemia vera (PV) and chronic severe splenomegaly, treated with

This review focuses on significant advances in the field of pediatric hemostasis and thrombosis, with a focus on published studies within the past decade. The evaluation and management of patients with excessive bleeding remain cornerstones of consultative hematology. We will describe the development of validated bleeding assessment tools relevant to pediatric practice, laboratory advances in the evaluation of von Willebrand disease, and a shift in clinical practice regarding the interpretation of normal coagulation studies in patients with significant bleeding phenotypes. There have also been critical advances in the management of hemostatic disorders. This review highlights new treatment paradigms in hemophilia and the rise of multidisciplinary medical homes for women living with bleeding disorders. Given the continued increase in the incidence of thrombosis, particularly in the hospital setting, a full call to arms against pediatric venous thromboembolism is now essential. We will describe recently completed clinical trials of direct oral anticoagulants in children and adolescents and ongoing work to elucidate the appropriate duration of therapy for children with provoked thrombosis. Recent work regarding the prevention of pediatric venous thromboembolism is highlighted, including studies of thromboprophylaxis and the development of risk prediction models for hospital-acquired thrombosis. Finally, we review advances in our understanding of thrombotic sequelae and the need for continued refinement of our evaluation tools. Despite the significant advances in pediatric hemostasis and thrombosis over the past decade, many unanswered questions remain for the next generation of investigators.

von Willebrand disease (VWD) disproportionately affects women because of the potential for heavy menstrual bleeding (HMB), delivery complications, and postpartum hemorrhage (PPH). To systematically synthesize the evidence regarding first-line management of HMB, treatment of women requiring or desiring neuraxial analgesia, and management of PPH. We searched Medline and EMBASE through October 2019 for randomized trials, comparative observational studies, and case series comparing the effects of desmopressin, hormonal therapy, and tranexamic acid (TxA) on HMB; comparing different von Willebrand factor (VWF) levels in women with VWD who were undergoing labor and receiving neuraxial anesthesia; and measuring the effects of TxA on PPH. We conducted duplicate study selection, data abstraction, and appraisal of risk of bias. Whenever possible, we conducted meta-analyses. We assessed the quality of the evidence using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach. We included 1 randomized trial, 3 comparative observational studies, and 10 case series. Moderate-certainty evidence showed that desmopressin resulted in a smaller reduction of menstrual blood loss (difference in mean change from baseline, 41.6 [95% confidence interval, 16.6-63.6] points in a pictorial blood assessment chart score) as compared with TxA. There was very-low-certainty evidence about how first-line treatments compare against each other, the effects of different VWF levels in women receiving neuraxial anesthesia, and the effects of postpartum administration of TxA. Most of the evidence relevant to the gynecologic and obstetric management of women with VWD addressed by most guidelines is very low quality. Future studies that address research priorities will be key when updating such guidelines.

Key Points HMB is associated with rare and common variants in genes related to anemias and bleeding disorders.These are the first exome-sequencing results from patients with HMB, as well as their comparison with control exomes., Visual Abstract, Adolescents with low von Willebrand factor (VWF) levels and heavy menstrual bleeding (HMB) experience significant morbidity. There is a need to better characterize these patients genetically and improve our understanding of the pathophysiology of bleeding. We performed whole-exome sequencing on 86 postmenarchal patients diagnosed with low VWF levels (30-50 IU/dL) and HMB and compared them with 660 in-house controls. We compared the number of rare stop-gain/stop-loss and rare ClinVar “pathogenic” variants between cases and controls, as well as performed gene burden and gene-set burden analyses. We found an enrichment in cases of rare stop-gain/stop-loss variants in genes involved in bleeding disorders and an enrichment of rare ClinVar “pathogenic” variants in genes involved in anemias. The 2 most significant genes in the gene burden analysis, CFB and DNASE2, are associated with atypical hemolytic uremia and severe anemia, respectively. VWF also surpassed exome-wide significance in the gene burden analysis (P = 7.31 × 10−6). Gene-set burden analysis revealed an enrichment of rare nonsynonymous variants in cases in several hematologically relevant pathways. Further, common variants in FERMT2, a gene involved in the regulation of hemostasis and angiogenesis, surpassed genome-wide significance. We demonstrate that adolescents with HMB and low VWF have an excess of rare nonsynonymous and pathogenic variants in genes involved in bleeding disorders and anemia. Variants of variable penetrance in these genes may contribute to the spectrum of phenotypes observed in patients with HMB and could partially explain the bleeding phenotype. By identifying patients with HMB who possess these variants, we may be able to improve risk stratification and patient outcomes.

von Willebrand disease (VWD) is the most common inherited bleeding disorder known in humans. Accurate and timely diagnosis presents numerous challenges.These evidence-based guidelines of the American Society of Hematology (ASH), the International Society on Thrombosis and Haemostasis (ISTH), the National Hemophilia Foundation (NHF), and the World Federation of Hemophilia (WFH) are intended to support patients, clinicians, and other health care professionals in their decisions about VWD diagnosis.ASH, ISTH, NHF, and WFH established a multidisciplinary guideline panel that included 4 patient representatives and was balanced to minimize potential bias from conflicts of interest. The Outcomes and Implementation Research Unit at the University of Kansas Medical Center (KUMC) supported the guideline-development process, including performing or updating systematic evidence reviews up to 8 January 2020. The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The panel used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, including GRADE Evidence-to-Decision frameworks, to assess evidence and make recommendations, which were subsequently subject to public comment.The panel agreed on 11 recommendations.Key recommendations of these guidelines include the role of bleeding-assessment tools in the assessment of patients suspected of VWD, diagnostic assays and laboratory cutoffs for type 1 and type 2 VWD, how to approach a type 1 VWD patient with normalized levels over time, and the role of genetic testing vs phenotypic assays for types 2B and 2N. Future critical research priorities are also identified.

Background The management of pregnant women with von Willebrand Disease (VWD) is complex as physiological pregnancy-induced increases in plasma von Willebrand Factor (VWF) may be blunted or absent. Women with VWD experience a heightened risk of postpartum haemorrhage (PPH) and special consideration must be given regarding neuraxial anaesthesia (NA) and the need for prophylaxis at time of delivery. These challenges are compounded by a lack of robust evidence to guide clinical decision making. Objectives & Methods To determine the current international clinical practises in the management of pregnancy for women with VWD, the International Society on Thrombosis and Haemostasis (ISTH) conducted an international survey of healthcare providers (HCP). Results 132 respondents from 39 countries were included in the final analysis. Variations in clinical practise were identified in antenatal (monitoring of plasma VWF and ferritin levels), peripartum (optimal plasma VWF target at delivery) and postpartum management (definitions used for PPH and postpartum monitoring). A key area of divergence was suitability for NA for women with type 2 and type 3 VWD, with many respondents advising against the use of NA even with VWF supplementation (29% type 2 VWD, 37% type 3 VWD) but others advising use once plasma VWF activity was was >50 IU/dL (57% type 2 VWD; 50% type 3 VWD). Conclusions This survey highlighted areas of uncertainty surrounding common management issues for pregnant women with VWD. These data underscore the need for international collaborative research efforts focused on peripartum management to improve care for pregnant women with VWD.

von Willebrand disease (VWD) is the most common inherited bleeding disorder. The management of patients with VWD who are undergoing surgeries is crucial to prevent bleeding complications. We systematically summarized the evidence on the management of patients with VWD who are undergoing major and minor surgeries to support the development of practice guidelines. We searched Medline and EMBASE from inception through October 2019 for randomized clinical trials (RCTs), comparative observational studies, and case series that compared maintaining factor VIII (FVIII) levels or von Willebrand factor (VWF) levels at >0.50 IU/mL for at least 3 days in patients undergoing major surgery, and those with options for perioperative management of patients undergoing minor surgery. Two authors screened and abstracted data and assessed the risk of bias. We conducted meta-analyses when possible. We evaluated the certainty of the evidence using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. We included 7 case series for major surgeries and 2 RCTs and 12 case series for minor surgeries. Very-low-certainty evidence showed that maintaining FVIII levels or VWF levels of >0.50 IU/mL for at least 3 consecutive days showed excellent hemostatic efficacy (as labeled by the researchers) after 74% to 100% of major surgeries. Low- to very-low-certainty evidence showed that prescribing tranexamic acid and increasing VWF levels to 0.50 IU/mL resulted in fewer bleeding complications after minor procedures compared with increasing VWF levels to 0.50 IU/mL alone. Given the low-quality evidence for guiding management decisions, a shared-decision model leading to individualized therapy plans will be important in patients with VWD who are undergoing surgical and invasive procedures.

Approach to the patient with bleeding begins with a thorough bleeding, medical, and family history to determine the nature of bleeding and severity of bleeding symptoms. Use of a Bleeding Assessment Tool allows the clinician to obtain a comprehensive bleeding history and ultimately determine the individual bleeding score that reflects bleeding severity and is classifiable as either normal or abnormal. In the absence of significant findings within patient history or presenting symptoms clearly pointing to a specific bleeding pathology, an approach to laboratory investigation is presented that proceeds through first-line, second-line, and third-line testing.

INTRODUCTION Von Willebrand disease (VWD) is the most common inherited bleeding disorder. The bleeding phenotype is variable, and some individuals have persistent symptoms post-diagnosis. AIM To characterize bleeding patterns in patients with VWD before and after diagnosis. METHODS De-identified claims data for commercially insured patients in the IQVIA PharMetrics® Plus US database (Jan-2006 to Jun-2015) were extracted. Eligible patients had ≥2 claims for VWD (ICD-9 code 286.4), and continuous health-plan enrolment for ≥2 years before and after diagnosis. Bleeding event, treatment and treating-physician type were analysed for 18 months before and 7-24 months after diagnosis, according to pre-diagnosis bleeding phenotype (claims from one vs multiple bleed sites) and post-diagnosis bleeding status (resolved [no post-diagnosis bleed claims] vs continued [≥1 claim]). RESULTS Data for 3756 eligible patients (72.6% female; 71.0% aged ≥18 years at diagnosis) were analysed. Overall, 642 (17.1%) and 805 (21.4%) patients had single- and multiple-site bleed claims pre-diagnosis, respectively, and 1263 (33.6%) patients (38.5% of women, 20.8% of men) continued to bleed post-diagnosis. Multiple-site bleeding was associated with pre-diagnosis heavy menstrual bleeding (HMB), oral contraceptive (OC) use and nasal cauterization. Continued bleeding post-diagnosis was associated with pre-diagnosis gastrointestinal bleeding, HMB and epistaxis; pre-diagnosis use of OCs, aminocaproic acid and nasal cauterization; and younger age at diagnosis. Few patients consulted a haematologist for bleed management. CONCLUSION Many patients with VWD have persistent bleeding from multiple sites and continue to bleed post-diagnosis. Our findings suggest a need to optimize management to reduce the symptomatic burden of VWD following diagnosis.

Type 1 von Willebrand disease (VWD) is the most common subtype of VWD, comprising 75% of VWD patients. We provide a systematic review of type 1 VWD in pregnancy. Our objective was to evaluate the rate of postpartum hemorrhage (PPH) in patients with known type 1 VWD. The primary outcome was rate of PPH. Primary PPH was defined as a cumulative blood loss ≥1,000 mL, or blood loss accompanied by signs and symptoms of hypovolemia within 24 hours postpartum or requiring blood products. Secondary PPH was defined as significant bleeding 24 hours to 12 weeks postpartum. Relevant articles published in English pertaining to VWD and pregnancy were identified without any time or study limitations. Seven articles (n = 144 pregnancies) met inclusion criteria. The rate of primary PPH was 4/144 (2.8%). The secondary PPH rate was reported in four studies, and occurred in 7/48 pregnancies (14.6%), ranging from 2 to 19 days postpartum. In conclusion, according to this systematic review, the frequency of primary PPH in pregnancies with known type 1 VWD is 2.8%. This is similar to the overall PPH rates of 3% reported in the literature. Although the sample size was small, secondary PPH occurred in almost 15% of pregnancies, while in the overall obstetrical population this occurs in approximately 1% of cases. Patients with known type 1 VWD may not be at increased risk of primary PPH, though they appear to bear increased risk of secondary PPH.

Acquired von Willebrand syndrome (AVWS) is a rare bleeding disorder caused by a reduced concentration and/or function of von Willebrand factor (VWF) with no prior or family history of congenital vo...

Introduction While it has been shown that haemophilia patients receiving care at Haemophilia Treatment Centres (HTCs) experience decreased morbidity and mortality, little research has been done on the outcomes of patients with von Willebrand disease (VWD). Aim To compare the quality of periprocedural care received by patients with VWD at HTCs and non-HTCs. Methods We performed a retrospective chart review on all adult VWD patients undergoing an invasive procedure from 2015 to 2017. Quality of periprocedural care was measured using the following surrogate outcomes: periprocedural VWD-specific therapy use per 2007 National Heart, Lung, and Blood Institute (NHLBI) guidelines, procedural estimated blood loss (EBL), and post-procedure bleeding. Comparisons were performed according to the setting of care at the time of the invasive procedure, HTC versus non-HTC. Results There were 668 invasive procedures performed on 305 patients, of which 8.2% were HTC cases. Non-type 1 VWD was more likely in HTC cases. VWD-specific therapy was used per NHLBI guidelines in 100% of HTC cases compared with 10.6% of non-HTC cases. Procedural EBL > = 100 ml was more likely to occur in HTC differences cases (OR = 2.34; 95% CI, 1.05 to 5.25). There was no difference in post-procedure bleeding between the two groups (OR = 1.26, 95% CI, .20- 7.86). Conclusion Despite widespread periprocedural use of VWD-specific therapy outside established guidelines at non-HTCs, there was no difference in periprocedural bleeding. Possible explanations include diagnostic error, in disease severity and procedure types, and dataset limitations. Additional studies are needed to investigate this further and compare other patient care outcomes between HTCs and non-HTCs.

Acquired von Willebrand disease (aVWD) is a rare disorder associated with a reduction in von Willebrand factor (VWF) activity, leading to increased bleeding risk. Monoclonal gammopathy of undetermined significance (MGUS) is the most common cause of lymphoproliferative disorder-associated aVWD and is caused by accelerated clearance of circulating VWF. Standard VWF replacement protocols for congenital VWD based on intermittent bolus dosing are typically less effective for aVWD because of antibody-mediated clearance. Intermittent bolus dosing of VWF concentrates often leads to inadequate peak response and profoundly shortened VWF half-life in aVWD. Intravenous immune globulin (IVIG) has demonstrated efficacy in aVWD; however, treatment effect is delayed up to 4 days, limiting its efficacy in acutely bleeding patients. We report the successful use of continuous-infusion VWF concentrate (with or without concomitant IVIG) in 3 patients with MGUS-associated aVWD who had demonstrated an inadequate response to bolus dosing. VWF concentrate doses required in this cohort were higher than typical doses for bleeding treatment in congenital VWD. This report illustrates that continuous-infusion VWF concentrate administration with or without intravenous immunoglobulin rapidly achieves target ristocetin cofactor activity and provides adequate hemostasis in aVWD associated with immunoglobulin G MGUS.

An adolescent female classified as unstable with a spontaneous abdominal hemorrhage was transferred to a level 1 pediatric trauma tertiary emergency department. Pertinent medical history included von Willebrand disease type 3, menorrhagia, and obesity. Preparation before patient arrival included mobilization of multidisciplinary medical team experts in hematology, pharmacy, blood bank, radiology, and nursing who provided lifesaving interventions. The administration of factor products, blood products, interventional radiology, emergent hepatic angiography, and embolization coordination resulted in a successful outcome. After an 18-day intensive hospital course, the patient returned home close to her baseline health status.

INTRODUCTION Published guidelines are available to assist in the management of patients with inherited bleeding disorders in the elective surgical setting however good quality outcome data is lacking. AIM - Evaluate the outcomes of adult patients with inherited bleeding disorders, who received factor replacement for elective surgery in NSW/ACT, Australia. - Assess adherence to relevant guidelines including Haemophilia Treatment Centre (HTC) utilisation and appropriate factor replacement. METHOD A retrospective analysis was performed between 2000 and 2018 to describe patient characteristics, surgical details, factor provision and outcomes. Univariate analysis was used to determine variables associated with guideline adherence. Covariates with p

It is well known that high von Willebrand factor (VWF) and factor VIII (FVIII) levels are associated with an increased risk of cardiovascular disease. It is still debated whether VWF and FVIII are biomarkers of endothelial dysfunction and atherosclerosis or whether they have a direct causative role. Therefore, we aimed to unravel the pathophysiological pathways of increased VWF and FVIII levels associated with cardiovascular risk factors. First, we performed a randomized controlled trial in 34 Göttingen miniswine. Diabetes mellitus (DM) was induced with streptozotocin and hypercholesterolemia (HC) via a high-fat diet in 18 swine (DM + HC), while 16 healthy swine served as controls. After 5 months of follow-up, FVIII activity (FVIII:C) was significantly higher in DM + HC swine (5.85 IU/mL [5.00–6.81]) compared with controls (4.57 [3.76–5.40], p = 0.010), whereas VWF antigen (VWF:Ag) was similar (respectively 0.34 IU/mL [0.28–0.39] vs. 0.34 [0.31–0.38], p = 0.644). DM + HC swine had no endothelial dysfunction or atherosclerosis during this short-term follow-up. Subsequently, we performed a long-term (15 months) longitudinal cohort study in 10 Landrace–Yorkshire swine, in five of which HC and in five combined DM + HC were induced. VWF:Ag was higher at 15 months compared with 9 months in HC (0.37 [0.32–0.42] vs. 0.27 [0.23–0.40], p = 0.042) and DM + HC (0.33 [0.32–0.37] vs. 0.25 [0.24–0.33], p = 0.042). Both long-term groups had endothelial dysfunction compared with controls and atherosclerosis after 15 months. In conclusion, short-term hyperglycemia and dyslipidemia increase FVIII, independent of VWF. Long-term DM and HC increase VWF via endothelial dysfunction and atherosclerosis. Therefore, VWF seems to be a biomarker for advanced cardiovascular disease.

Background: Thromboembolism and bleeding contribute to Coronavirus disease 2019 (COVID-19)’s morbidity and mortality and are also frequent complications of venovenous extracorporeal membrane oxygenation (vvECMO). As the interaction of the underlying pathologies caused by vvECMO in COVID-19 is barely understood, we designed this study to better differentiate coagulation disorders in COVID-19 patients before, during and after vvECMO-support. Methods: Observational case series, six consecutive patients with Coronavirus acute respiratory distress syndrome supported with vvECMO treated in the anaesthesiologic ICU in a third level University ECMO-centre. We measured routine coagulation parameters and assessed coagulation factors. We also conducted advanced von Willebrand factor (VWF) multimer analysis, platelet aggregometry and immunological screening. Results: We identified various phases of coagulation disorders: Initially, intensely activated coagulation with highly increased VWF and factor VIII activity in acute COVID-19, then severe acquired von Willebrand syndrome and platelet dysfunction during vvECMO leading to spontaneous bleeding and finally, hypercoagulopathy after vvECMO explantation. Five of six patients developed immunological abnormalities enhancing coagulation. Conclusions: Coronavirus-induced coagulopathy and bleeding disorders during vvECMO cannot be discriminated via ‘routine’ coagulation tests. Precise and specific analyses followed by the appropriate treatment of coagulation disorders may help us develop tailored therapeutic concepts to better manage the phases described above.

Background Factor VIII (FVIII) pharmacokinetics (PK) in adult hemophilia A populations are highly variable and have been previously determined to be influenced by von Willebrand factor:antigen (VWF:Ag), ABO blood group, and age. However, additional genetic determinants of FVIII PK are largely unknown. Objectives The contribution of VWF clearance, VWF-FVIII-binding activity, and genetic variants in VWF clearance receptors to FVIII PK in adult patients were assessed. Methods FVIII PK assessment was performed in 44 adult subjects (age 18-61 years) with moderate or severe hemophilia A. VWF:Ag, VWF propeptide (VWFpp), VWFpp/VWF:Ag, and VWF:FVIII binding activity were measured. The VWF modifying loci CLEC4M, SCARA5, STAB2, and ABO, and the D'D3 FVIII-binding region of the VWF gene were genotyped. Results VWF:Ag, VWFpp, and VWF:FVIIIB positively correlated with FVIII half-life and negatively correlated with FVIII clearance. VWFpp/VWF:Ag negatively correlated with FVIII half-life and positively correlated with FVIII clearance. The correlation between VWFpp/VWF:Ag and FVIII half-life was stronger for type non-O patients than for type O patients, suggesting that slower VWF clearance increases FVIII half-life. Patients heterozygous for the CLEC4M rs868875 variant had increased FVIII clearance when compared with individuals homozygous for the reference allele. The CLEC4M variable number of tandem repeat (VNTR) alleles were also associated with the rate of FVIII clearance. When compared with the quartile of patients with the fastest FVIII clearance, the quartile of patients with the slowest FVIII clearance had a decreased frequency of the CLEC4M 5-VNTR. Conclusions VWF-FVIII binding activity and genetic determinants of VWF clearance are important contributors to FVIII pharmacokinetics in adult patients.

Objective To review the use of Von Willebrand Factor (VWF) concentrate for treatment of acquired Von Willebrand syndrome (VWS) related bleeding in adult extracorporeal membrane oxygenation (ECMO) patients and determine whether it was associated with improved VWF laboratory parameters. Design Retrospective observational cohort study. Setting Tertiary care academic medical center. Participants Adult ECMO patients who received VWF concentrate for treatment of acquired VWS related bleeding. Interventions None, observational study. Measurements and Main Results Ten adult ECMO patients received VWF concentrate for treatment of bleeding with evidence of acquired VWS over a 15-month period. Six patients were on veno-arterial ECMO and 4 were on veno-venous ECMO. The most common site of bleeding was airway or tracheal bleeding. The mean dose of VWF concentrate was 41 IU/kg. Mean VWF antigen was 263 ± 93 IU/dL before treatment and 394 ± 54 after treatment. Mean ristocetin cofactor activity was 127 ± 47 IU/dL before treatment and 240 ± 33 after treatment. The mean VWF ristocetin cofactor activity antigen ratio increased from 0.52 ± 0.14 before treatment to 0.62 ± 0.04 after treatment. Four of 10 patients had complete resolution of their bleeding within 24 hours while 6 of 10 had complete resolution of their bleeding within 2 to 4 days. There were 3 patients who had thrombotic events potentially related to VWF concentrate administration. No patient had an arterial thrombosis, stroke, or myocardial infarction. Conclusions VWF concentrate administration increases VWF function in adult ECMO patients, but may also be associated with increased thrombotic risk. Larger studies are needed to determine VWF concentrate's safety, efficacy, and optimal dosing in adult ECMO patients.

Introduction There is limited awareness of von Willebrand disease (VWD), leading to challenges in both diagnosis and defining the optimal treatment approach for these patients. Patients with VWD are typically treated on-demand, with short-term prophylaxis used during surgery. In contrast, early initiation, and long-term use of prophylaxis is the standard of care in patients with severe haemophilia and can be successfully used to prevent joint bleeding and reduce chronic arthropathy. Aim To provide an understanding of the current evidence for the prophylactic treatment of patients with VWD and compare this to the management of patients with haemophilia. Methods Review of published literature using a non-systematic search of PubMed and reference lists of sourced articles. Results The successes seen with prophylaxis in haemophilia provide the rationale for long-term prophylaxis in patients with severe forms of VWD; preventing spontaneous, excessive and sometimes life-threatening bleeding, and reducing chronic joint disease. Currently, there are a few clinical trials assessing the long-term benefits of prophylaxis in VWD, and guidelines for the optimal prophylaxis treatment approach are lacking. Greater attempts to provide comprehensive, long-term care for patients with VWD are needed but still lacking within the community. This review highlights the success of prophylaxis in haemophilia and how this knowledge might be applied and translated to patients with VWD. Conclusions Lessons can be learned from the use of prophylaxis in haemophilia and prophylaxis should be considered the standard of care for a subgroup of patients with severe VWD.

Von Willebrand disease (VWD) is the most frequent inherited bleeding disorder caused by quantitative or qualitative defects of von Willebrand factor (VWF). This protein far from simplicity constitutes a very complex molecular model, remaining unravelled yet many aspects of it, even though the VWF gene (VWF) was cloned already in 1985 and the structure of VWF well defined. VWD diagnosis is difficult to achieve in a significant proportion of patients due to both disease heterogeneity and limitations in existing test processes. The cornerstone of diagnosis relies on interpretation of VWF test results, the presence of clinical manifestations of bleeding, especially mucocutaneous, and (in most cases) a positive family history. However, even with a significant bleeding history, a family history may not be positive due to factors of incomplete penetrance and variable expressivity that affect genetic changes. The laboratory diagnosis of VWD can be difficult, as the disease is heterogeneous and an array of assays is required to describe the phenotype. Basic classification of quantitative (type 1 and 3) and qualitative (type 2 variants) VWD requires determination of VWF antigenic (VWF:Ag) levels and assaying of VWF ristocetin cofactor (VWF:RCo) activity. The latter is required for identifying and subtyping VWD, but the assay is poorly standardized. For that reason, novel VWF activity assays have been developed awaiting more extensive comparison data between different methodologies and requiring validation on larger patient series. The qualitative type 2 VWF deficiency can be further divided into four different subtypes (A, B, M and N) using specific assays that measure other activities or the size distribution of VWF multimers. However, frequently, it may be difficult to correctly classify the VWD phenotype, and genetic analysis is through mutation identification may provide a tool to clarify the disorder.

INTRODUCTION Menorrhagia impacts ~40% of adolescent females, with about half having an underlying bleeding disorder, most commonly von Willebrand Disease (VWD). VWD affects ~1 in 1000 individuals, though many are unaware of their condition. Let's Talk Period (LTP) is an online knowledge translation platform aimed at increasing awareness of bleeding disorders symptoms, with a validated self-administered bleeding assessment tool (Self-BAT). AIM To evaluate the effectiveness of the LTP high school outreach program in Grade 9 girls' health classes quantitatively, using baseline, post-presentation, and follow-up quiz scores, and qualitatively, with student and teacher feedback forms. METHODS The 75-minute in-class presentations, developed in alignment with the 2015 Ontario Curriculum for Grade 9 Health and Physical Activity, were led by a haemophilia nurse, clinical research assistant, and undergraduate student from the LTP team. Students completed baseline, post-presentation, and 4-6-week follow-up Kahoot quizzes featuring the same nine questions to evaluate change in knowledge levels and retention. Both student and teacher feedback were collected. RESULTS There was a significant increase (p

Introduction Von Willebrand Disease is a common inherited haemorrhagic disorder due to a deficiency of Von Willebrand Factor (VWF). In case of surgical procedures in patients who are not responsive or have contraindications to desmopressin, replacement therapy with VWF concentrates is indicated. Until recently, only plasma-derived VWF concentrates were available. A new recombinant VWF (rVWF) concentrate that contains no Factor VIII (FVIII) but a high amount of high molecular weight VWF multimers has been available in France since 2018. Aim Describe real-world experience of using rVWF in surgical procedures. Methods Sixty-three surgeries for 55 patients were retrospectively analysed in 7 French haemostasis centres. Results During minor surgeries, the median (range) number of infusions was 1 (1-8) with a preoperative loading dose of 35 (19-56) rVWF IU/kg and a total median dose of 37.5 IU (12-288). During major surgeries, the median (range) number of infusions was only 3 (1-14) with a median preoperative loading dose of 36 IU (12-51) rVWF IU/kg, and a total median dose of 108 IU (22-340) rVWF IU/kg. The overall clinical efficacy was qualified as excellent/good in 61 of the procedures (97%), moderate in 1 (1.5%) and poor in 1 (1.5%). There was no accumulation of VWF or FVIII during postoperative monitoring. No thromboembolic events, anti-VWF antibodies or adverse events were reported. Conclusion This French 'real-world' experience shows that a few infusions and low doses of rVWF provided effective prevention of bleeding in major and minor surgeries in inherited VWD, with no clinically significant safety concerns.

Introduction Type 2N von Willebrand disease (2NVWD) is characterized by a mild to moderate reduction in plasma levels of factor (F)VIII associated with defective binding of von Willebrand factor (VWF) to FVIII and accelerated proteolysis and clearance of FVIII. The clinical phenotype in 2NVWD is often indistinguishable from mild/moderate hemophilia (H)A. Emicizumab is a bispecific antibody to FIX/FIXa and FX/FXa that mimics FVIIIa cofactor function, and emicizumab prophylaxis significantly reduces bleeding events in patients with severe HA. Aim We investigated the potential benefits of emicizumab in the hemostatic management of 2NVWD. Patients/methods Perfusion chamber experiments were performed using whole blood from three 2NVWD patients with different clinical phenotypes (bleeding scores: 0, 6 and 20; mutations: p.R816W, p.R816W, and p.R365X/p.T791M, respectively). Furthermore, the impact of specific FVIII-VWF interactions on thrombus formation was investigated. Results Defective thrombus formation that correlated with bleeding phenotype was evident in these 2NVWD patients. Emicizumab improved surface coverage and thrombus height in all cases. Multi-color immunostaining of thrombi further demonstrated that emicizumab enhanced thrombin generation and fibrin formation. The addition of FVIII alone to 2NVWD whole blood did not augment thrombus formation, while supplementation with FVIII/VWF complex enhanced platelet-fibrin interactions. Furthermore, an anti-FVIII monoclonal antibody known to interrupt the release of FVIIIa from VWF depressed these effects. Conclusions Emicizumab-induced enhancing effects of thrombus formation, independent on VWF, might be useful as an alternative therapy for 2NVWD patients. The extent of FVIII-VWF interaction should be optimal to deliver and release FVIII/FVIIIa on the activated platelet surface.

Background: von Willebrand disease (VWD) is a common inherited bleeding disorder. Significant variability exists in management options offered to patients. Objective: These evidence-based guidelines from the American Society of Hematology (ASH), the International Society on Thrombosis and Haemostasis (ISTH), the National Hemophilia Foundation (NHF), and the World Federation of Hemophilia (WFH) are intended to support patients, clinicians, and health care professionals in their decisions about management of VWD. Methods: ASH, ISTH, NHF, and WFH formed a multidisciplinary guideline panel. Three patient representatives were included. The panel was balanced to minimize potential bias from conflicts of interest. The University of Kansas Outcomes and Implementation Research Unit and the McMaster Grading of Recommendations Assessment, Development and Evaluation (GRADE) Centre supported the guideline development process, including performing and updating systematic evidence reviews (through November 2019). The panel prioritized clinical questions and outcomes according to their importance to clinicians and patients. The panel used the GRADE approach, including GRADE Evidence-to-Decision frameworks, to assess evidence and make recommendations, which were subject to public comment. Results: The panel agreed on 12 recommendations and outlined future research priorities. Conclusions: These guidelines make key recommendations regarding prophylaxis for frequent recurrent bleeding, desmopressin trials to determine therapy, use of antiplatelet agents and anticoagulant therapy, target VWF and factor VIII activity levels for major surgery, strategies to reduce bleeding during minor surgery or invasive procedures, management options for heavy menstrual bleeding, management of VWD in the context of neuraxial anesthesia during labor and delivery, and management in the postpartum setting.

The interaction of platelets with von Willebrand factor is essential for primary hemostasis. Concentration and activity of plasma von Willebrand factor are routine parameters in the assessment of hemostasis disorders. In addition to plasma von Willebrand factor, platelet von Willebrand factor, synthesized in megakaryocytes and stored in α-granules of circulating platelets, is known to contribute to primary hemostasis and the microenvironment of thrombus formation. The laboratory assessment of platelet von Willebrand factor however is cumbersome and not widely established as a routine parameter. We here propose a method for laboratory assessment and reporting of platelet von Willebrand factor potentially useful for laboratory routines in specialized laboratories. Our model allows to describe platelet von Willebrand factor as 1. the concentration of platelet von Willebrand factor in whole blood, 2. the amount of platelet von Willebrand factor in a sample with a defined concentration of 1000 platelets/nl, and 3. the concentration of platelet von Willebrand factor in one platelet. According to our results in healthy individuals, the proportion of platelet von Willebrand factor activity is estimated to be about 10% of total von Willebrand factor in human plasma under physiological circumstances. The concentration of platelet von Willebrand factor is estimated to be 0.4 IU/ml in a sample with a defined concentration of 1000 platelets/nl and to be about 42 IU/ml in one platelet (both expressed as VWF:Ag).

Essentials Patients with von Willebrand disease were enrolled in our study. Type 2 VWD diagnoses were based on original test results. Repeat evaluation resulted in many patients receiving a different type 2 diagnosis. Some genetic variants were particularly likely to move type 2 subcategories. ABSTRACT: Introduction Type 2 von Willebrand disease (VWD) refers to patients with a qualitative defect in von Willebrand factor. Accurate diagnosis of type 2 VWD subtypes can be challenging. Aim of the study To compare the historical diagnosis of type 2 VWD with current laboratory testing. Methods Subjects were enrolled in the Zimmerman Program either because of a preexisting diagnosis of VWD (retrospective cohort) or from evaluation for bleeding symptoms or suspected VWD (prospective cohort). Original diagnosis was assigned by the local center and central diagnosis was based on central laboratory testing. Results Two hundred and seventeen index cases in the retrospective cohort and 35 subjects in the prospective cohort carried a local diagnosis of type 2 VWD (29% and 6% of enrolled index cases, respectively). In the retrospective cohort, the diagnosis was confirmed in 66% of cases with a preexisting diagnosis of 2A, 77% 2B, 54% 2M, and 72% 2N. In the prospective cohort, 31% were confirmed 2A, 60% 2B, 23% 2M, and 100% 2N. Several genetic variants were repeatedly implicated in subjects with changed diagnosis: p.M1304R, p.R1315C, p.R1374C, and p.R1374H. Conclusions Both the prospective and retrospective cohorts demonstrated consistent variation in subjects whose diagnosis changed between 2A, 2B, and 2M. The importance of accurately diagnosing type 2 VWD may be most significant in the 2B subtype given potential concerns with the use of desmopressin in type 2B VWD. Some genetic variants appear in multiple types of VWD, making specific diagnoses challenging.

Acquired von Willebrand syndrome (AVWS) is a rare, frequently underdiagnosed and underestimated bleeding disorder. Careful personal and family history and late-onset mucocutaneous bleeding could help clarify the etiology of bleeding deficiency.An 82-year-old male patient was admitted to our clinic with a severe nosebleed on 30.05.2018. Laboratory results revealed thrombocytosis, elevated white blood cell count and high LDH. Basic coagulation parameters were normal. He was referred to our clinic, where a bone marrow biopsy was taken. His personal and family history had no mention of bleeding disorders, nor was he on anticoagulant therapy. We detected elevated VWF antigen and decreased VWF ristocetin cofactor activity. Loss of high molecular weight multimers was detected by using agarose gel electrophoresis. These laboratory results were indicative of AVWS. Hydroxyurea treatment was initiated, leading to a gradual decrease in platelet count. The histological examination revealed essential thrombocytosist while mutation analysis was JAK2/CALR/MPL negative. However, due to severe nosebleeds, the patient was hospitalized and needed blood transfusion. A cardiological check-up revealed the progression of aortic valve stenosis. After, balloon-dilation a transcatheter aortic valve implantation was performed. As a result, VWF activity and activity to antigen ratio returned to normal as did multimeric structure. In July 2019, the follow-up examination showed that the patient was in a satisfactory condition, with normal hematological parameters, and no new nosebleed episode occurred.The patient complained of recurring nosebleeds, which stopped completely after the resolution of both underlying conditions successful cytoreductive treatment of triple-negative ET and transcatheteric aortic valve replacement.

Women with bleeding disorders suffer from multiple bleeding symptoms, including easy bruising, epistaxis, bleeding from minor wounds and the oral cavity, and bleeding after dental work or surgery. However, women with bleeding disorders especially suffer from gynecologic and obstetrical bleeding. These symptoms often are not recognized as abnormal, and many women are left undiagnosed and without access to appropriate medical care. Additional challenges to diagnosing women with bleeding disorders include lack of access to appropriate laboratory testing and issues around disease classification and nomenclature. Efforts have been undertaken to address these challenges, including the development and validation of bleeding assessment tools and strategies to clarify diagnostic thresholds and algorithms for von Willebrand disease (VWD) and platelet function disorders. Efforts to improve communication with the nomenclature used for hemophilia carriers are also underway.

von Willebrand disease (VWD) is a common autosomally inherited hemorrhagic disorder mainly associated with mucocutaneous bleeding. VWD is due to quantitative (type 1 and 3) or qualitative (type 2) defects of von Willebrand factor (VWF), a large multimeric plasma glycoprotein that plays a relevant role in hemostasis. VWF is essential to mediate platelet adhesion and aggregation at the sites of vascular injury under high shear stress conditions. VWF also carries coagulation factor VIII (FVIII), prolonging its half-life and concentrating it at the site of the damaged endothelium. The diagnosis of VWD, in agreement with the International Society for Thrombosis and Hemostasis guidelines, requires several assays that are necessary to evaluate the capacity of VWF to interact with several ligands, e.g. platelet glycoprotein Ibα, collagen and FVIII. Therefore, the differential diagnosis of VWD patients as type 1, 2A, 2B, 2M, 2N or 3 is a prerogative of specialized laboratories, where specific tests, like multimer analysis or ristocetin-induced platelet agglutination, are performed routinely. On the other hand, the basic identification of patients with VWD is nowadays possible in many hemostasis laboratories thanks to the availability of automated tests that measure in patient plasma VWF antigen levels and its platelet-dependent activity. Nevertheless the laboratory investigation for VWD of a subject referred for a hemorrhagic tendency should start only after the attending physician, after evaluation of his/her personal and family bleeding history, confirmed the suspicion for VWD. The purpose of this manuscript is to give an overview of the complex process that leads to the diagnosis of the VWD.

Objective To describe a complex case involving the management of a dog with von Willebrand disease (vWD), active ehrlichiosis infection, nonregenerative anemia, and blood type incompatibility related to the Dal antigen. Case summary A 13-week-oldintact male Doberman Pinscher weighing 7.2 kg was presented to the emergency service for a previous hemorrhaging event and progressive nonregenerative anemia. The dog had received a fresh whole blood transfusion 8 days prior to presentation due to severe anemia. Upon presentation, the puppy was tachycardic, and his mucous membranes were pale. A CBC revealed a nonregenerative anemia with a PCV of 0.11 L/L (11%). von Willebrand factor deficiency was suspected and later confirmed. The dog's blood type was dog erythrocyte antigen (DEA) 1 positive, but cross-matching to 4 RBC units, both DEA 1 positive and negative, failed to yield any compatible units. Antibody against a possible Dal RBC antigen was suspected, and 11 blood donors (Dalmatians and Dobermans) were cross-matched to find 2 compatible donors. After an uneventful fresh whole blood transfusion, a bone marrow biopsy revealed a hypocellular bone marrow and erythroid hypoplasia. A SNAP4DxPlus test and subsequent polymerase chain reaction (PCR) testing were positive for Ehrlichia ewingii and E. canis. Treatment with doxycycline was started, and the PCV was 0.17 L/L (17%) at discharge. At the 1-week follow-up, the PCV was 0.24 L/L (24%), and the puppy was doing well. New or unique information provided This is a unique case of a dog presenting with several challenging disorders, including vWD resulting in hemorrhage, ehrlichiosis potentially contributing to a nonregenerative anemia, and a blood type incompatibility due to the Dal antigen. Doberman Pinschers have a high prevalence of vWD- and Dal-negative phenotype, which emphasizes the value of cross-matching and the recognition of antigen prevalence in specific breeds.

Introduction HaemoassistTM 2 is an electronic system designed for people with bleeding disorders and their physicians to record prophylactic infusions and treatment of bleeds. It aims to improve adherence by permitting reminders and accuracy of documentation by facilitating real-time reporting. Aim To assess documentation quality and adherence to prophylactic regimens in patients with haemophilia A, haemophilia B or von Willebrand disease who are using HaemoassistTM 2. Methods Ten centres enrolled consecutive patients, who had been using HaemoassistTM 2 for ≥ 3 months (Cohort 1, 'quality of documentation'). Of these, patients who had a specified prophylactic regimen in HaemoassistTM 2 for ≥ 3 months were eligible for inclusion in Cohort 2 ('adherence to prophylaxis'). Results Cohort 1 comprised 796 patients (71% with severe haemophilia A; median 20.5 months of HaemoassistTM 2 use). The most common method of documentation for patients was using the mobile app; the median time between infusion and documentation was 4 hours using the app, compared with 85 hours using a web portal on a stationery device. The median total annualised number of infusions was consistent in the first and last 3 months of documentation (128; IQR: 70-184 and 120; IQR 64-176, respectively). Cohort 2 comprised 202 patients (79% severe haemophilia A; median of 13 months on prophylactic regimen in HaemoassistTM 2). The rate of adherence to prophylaxis was 83%; median deviation between planned and actual infusion time was ± 2 hours. Conclusion HaemoassistTM 2 was used consistently over prolonged periods of time and allowed for precise analysis of adherence to prophylaxis.

Objective Most von Willebrand disease (VWD) patients can be treated with desmopressin during bleeding or surgery. Large interpatient variability is observed in von Willebrand factor (VWF) activity levels after desmopressin administration. The aim of this study was to develop a pharmacokinetic (PK) model to describe, quantify, and explain this variability. Methods Patients with either VWD or low VWF, receiving an intravenous desmopressin test dose of 0.3 µg kg−1, were included. A PK model was derived on the basis of the individual time profiles of VWF activity. Since no VWF was administered, the VWF dose was arbitrarily set to unity. Interpatient variability in bioavailability (F), volume of distribution (V), and clearance (Cl) was estimated. Results The PK model was developed using 951 VWF activity level measurements from 207 patients diagnosed with a VWD type. Median age was 28 years (range: 5–76), median predose VWF activity was 0.37 IU/mL (range: 0.06–1.13), and median VWF activity response at peak level was 0.64 IU/mL (range: 0.04–4.04). The observed PK profiles were best described using a one-compartment model with allometric scaling. While F increased with age, Cl was dependent on VWD type and sex. Inclusion resulted in a drop in interpatient variability in F and Cl of 81.7 to 60.5% and 92.8 to 76.5%, respectively. Conclusion A PK model was developed, describing VWF activity versus time profile after desmopressin administration in patients with VWD or low VWF. Interpatient variability in response was quantified and partially explained. This model is a starting point toward more accurate prediction of desmopressin dosing effects in VWD.

Background : Bleeding assessment tools (BATs) have been developed to quantify bleeding severity. Their ability to predict for the diagnosis of a bleeding disorder has not been thoroughly investigated. Objectives : To evaluate the ability of the Vicenza BAT and the ISTH BAT to distinguish patients with an established bleeding disorder from those with bleeding of unknown cause (BUC). Patients/Methods : Three-hundred fifty-nine patients (228 with BUC, 64%) from the Vienna Bleeding Biobank were assessed in this study. Results : The bleeding scores were similar in patients with an established diagnosis of a bleeding disorder compared to patients with BUC. Both BATs had a low sensitivity and specificity for the diagnosis of a bleeding disorder with areas under the receiver operating characteristic (ROC) curves of 0.53 (95% confidence interval 0.47–0.60) for the Vicenza BAT and 0.52 (0.46–0.59) for the ISTH BAT. In terms of specific diagnoses, both scores were most accurate in diagnosing von Willebrand disease (VWD, areas under the ROC curve; Vicenza BAT 0.67 (0.45–0.90); ISTH BAT 0.70 (0.50–0.90)). A separate evaluation of different bleeding symptoms in patients who had undergone surgery and tooth extraction revealed that postpartum bleeding and bleeding from small wounds was predictive for diagnosing a MBD in multivariable analysis. Conclusions : The Vicenza- and the ISTH BAT have a low ability to distinguish patients with an established bleeding disorder from those with BUC.

von Willebrand disease (VWD) is a congenital bleeding disorder characterized by deficient or defective von Willebrand factor (VWF). Among women with VWD, postpartum hemorrhage (PPH) is common. Treatment options at delivery include plasma-derived VWF (pdVWF) and recombinant VWF (rVWF). However, limited data are available regarding their efficacy. We conducted a retrospective observational study comparing PPH in women with VWD treated at the Hemophilia Center of Western Pennsylvania between 1 February 2017 and 31 January 2018 with either rVWF or pdVWF. We compared postpartum outcomes, including PPH frequency and estimated blood loss (EBL) at delivery. There were a total of 12 deliveries, 7 vaginal and 5 cesarean. At delivery and for 3 days postpartum, 6 women received 80 IU/kg of rVWF and 6 received 80 IU/kg of pdVWF, based on prepregnancy weight, insurance, and/or patient choice. Treatment groups had similar demographics, including median age (32.0 vs 27.0 years; P = .075), bleeding scores (3.0 vs 3.5; P = .734), and prepregnancy body mass index (29.0 vs 29.2 kg/m2; P = .691). PPH occurred in 3 (25.0%) of 12 deliveries, with no difference by treatment group (2 of 6 rVWF vs 1 of 6 pdVWF; P = 1.000) and no difference in EBL by treatment group (685 vs 462 mL; P = .384) or delivery type (vaginal, P = .722 vs cesarean, P = .531). In summary, PPH occurred in one-fourth of the deliveries in women with VWD, despite a higher dose (80 IU/kg) of rVWF or pdVWF. Future trials are needed to develop and assess novel strategies to prevent PPH in VWD.

von Willebrand disease (VWD) constitutes the most common inherited human bleeding disorder. Partial quantitative von Willebrand factor (VWF) deficiency is responsible for the majority of VWD cases. International guidelines recommend that patients with mild to moderate reductions in plasma VWF antigen (VWF:Ag) levels (typically in the range of 30-50 IU/dL) should be diagnosed with low VWF. Over the past decade, a series of large cohort studies have provided significant insights into the biological mechanisms involved in type 1 VWD (plasma VWF:Ag levels

Identification of qualitative variants of von Willebrand disease (VWD) can be a diagnostic challenge because of discrepant results obtained in the multiple laboratory tests available for its appropriate classification. We report two cases of infrequent inherited variants of VWD with unclear preliminary results with the test panel available at the time of first consultation and that were finally diagnosed as a VWD type 2A/IID with a c.8318 G C, p.Cys2773Ser mutation and a VWD type 2M with c.4225 T G, p.Val1409Phe mutation, respectively. The description of these two cases highlights that despite the limited diagnostic panel for the evaluation of von Willebrand Factor (VWF) functionality, the multimeric analysis and genetic family studies were fundamental tools to achieve the final diagnosis.

Background Hemophilia carriers (HCs) face specific psychosocial challenges related to pregnancy, caused by their inherited bleeding disorder. Optimal support from healthcare providers can only be realized by exploring medical and psychological healthcare requirements. Objective To review all published evidence on the experiences and attitudes of HCs regarding reproductive decision‐making, prenatal diagnosis, pregnancy, childbirth, and puerperium to provide an accessible overview of this information for health care providers. Study selection Cochrane library, PubMed/MEDLINE, EMBASE, CINAHL, and PsycINFO were searched for original qualitative data. Two authors performed study selection, risk‐of‐bias assessment, data extraction, and data analysis through meta‐summary. The extracted themes were discussed within the research team. Findings Fifteen studies with an overall moderate quality were included. The following findings were identified: (a) Quality of life of family members with hemophilia influences reproductive decision‐making; (b) Genetic counselling is generally considered useful; (c) The development of a specialized carrier clinic is considered valuable; (d) HCs describe prenatal diagnosis as beneficial yet psychosocially challenging; and (e) noninvasive prenatal diagnosis and preimplantation genetic diagnosis are predominantly considered beneficial. These findings are limited by the overall moderate quality of included studies and the possibly partly outdated results in the current era of hemophilia treatment. Conclusions Available qualitative literature on HCs around pregnancy focuses on genetic counselling and prenatal diagnosis. Future studies are needed on the experiences and needs of HCs through pregnancy and puerperium as well as in light of emerging hemophilia diagnosis and treatment options.

Increased awareness of von Willebrand Disease (VWD) has led to more frequent diagnostic laboratory testing, which insurers often dictate be performed at a facility with off-site laboratory processing, instead of a coagulation facility with onsite processing. Off-site processing is more prone to preanalytical variables causing falsely low levels of von Willebrand Factor (VWF) due to the additional transport required. Our aim was to determine the percentage of discordance between off-site and onsite specimen processing for VWD in this multicenter, retrospective study. We enrolled females aged 12 to 50 years who had off-site specimen processing for VWF assays, and repeat testing performed at a consulting institution with onsite coagulation phlebotomy and processing. A total of 263 females from 17 institutions were included in the analysis. There were 251 subjects with both off-site and onsite VWF antigen (VWF:Ag) processing with 96 (38IU/dL) being low off-site and 56 (22IU/dL) low onsite; 223 subjects had VWF ristocetin co-factor (VWF:RCo), 122 (55IU/dL) were low off-site and 71 (32IU/dL) were low onsite. Similarly, 229 subjects had a Factor VIII (FVIII) assay, and 67 (29IU/dL) were low off-site with less than half, 29 (13IU/dL) confirmed low with onsite processing. Higher proportions of patients demonstrated low VWF:Ag, VWF:RCo, and/or FVIII with off-site processing compared to onsite (McNemar's test P-value

The acquired von Willebrand syndrome (AvWS) is a rare bleeding disorder with laboratory findings similar to those of inherited von Willebrand disease. However, unlike the inherited disease, AvWS occurs in persons with no personal and family history of bleeding and is often associated with a variety of underlying diseases, most frequently lymphoproliferative, myeloproliferative and cardiovascular disorders. After the presentation of a typical case, in this narrative review we discuss the more recent data on the pathophysiology, clinical, laboratory and therapeutic aspects of this acquired bleeding syndrome. We chose to focus particularly on those aspects of greater interest for the hematologist.

Introduction The World Federation of Hemophilia (WFH) strives to achieve care for all patients with inherited bleeding disorders through research, advocacy, capacity building and education. The WFH developed and implemented the Annual Global Survey (AGS), through which comprehensive demographic and treatment data on bleeding disorders are collected each year from its constituent non-governmental national organizations. Aim To describe the development, methodology and achievements of the WFH AGS over the past 20 years. Methods The AGS is a yearly cross-sectional survey. Data are collected using a standardized form (available online and on paper), quality checked and reviewed, and published in English, French and Spanish. Over time, the AGS has been modified in response to changes in treatment landscape or emerging new issues. Results Over the past 20 years, the AGS has reported an increase in the number of countries participating in the survey, a tripling in the number of people identified with rare bleeding disorders and an increase in the amount of factor used to treat people with haemophilia. Yet, a large treatment inequity gap still exists across the globe. In response to this gap, the WFH has analysed the AGS reports which has stimulated further development in quality of care indicators, estimates of the global prevalence of haemophilia, patient-level data collection efforts like the World Bleeding Disorders Registry and the Gene Therapy Registry. Conclusion The AGS has provided evidence to support research, programme planning and development activities of the WFH.

Acquired bleeding disorders can accompany hematological, neoplastic, autoimmune, cardiovascular or liver diseases, but can sometimes also arise spontaneously. They can manifest as single factor deficiencies or as complex hemostatic abnormalities. This review addresses (a) acquired hemophilia A, an autoimmune disorder characterized by inhibitory autoantibodies against coagulation factor VIII; (b) acquired von Willebrand syndrome in patients with cardiovascular disorders, where shear stress abnormalities result in destruction of von Willebrand factor; and (c) liver function disorders that comprise complex changes in pro- and anti-hemostatic factors, whose clinical implications are often difficult to predict. The article provides an overview on the pathophysiology, diagnostic tests and state-of-the-art treatment strategies.

A unique feature of the flow-diverting stent (FDS) has rendered it useful in the endovascular treatment of selected intracranial aneurysms for the last decade. Delayed aneurysmal rupture and intracranial parenchymal bleeding are two leading hemorrhagic complications after FDS. It has recently been shown for the first time that there is a relationship between FDS and reduced level of vWF activity in patients undergoing endovascular cerebral aneurysm treatment. Here, the current literature is reviewed in the context of this novel finding to propose an illustrative scenario that conceptually links implantation of FDS to delayed intracranial bleeding, through the mechanism of shear-induced activation of vWF. In this scenario, after FDS implantation, sustained release of activated vWF in association with platelets plays a pivotal role in the mechanisms of delayed intracranial hemorrhages.

Von Willebrand disease (VWD) constitutes the most common inherited human bleeding disorder. It is associated with a mucocutaneous bleeding phenotype that can significantly impact upon quality of life. Despite its prevalence and associated morbidity, the diagnosis and subclassification of VWD continue to pose significant clinical challenges. This is in part attributable to the fact that plasma von Willebrand factor (VWF) levels vary over a wide range in the normal population, together with the multiple different physiological functions played by VWF in vivo. Over recent years, substantial progress has been achieved in elucidating the biological roles of VWF. Significant advances have also been made into defining the pathophysiological mechanisms underpinning both quantitative and qualitative VWD. In particular, several new laboratory assays have been developed that enable more precise assessment of specific aspects of VWF activity. In the present review, we discuss these recent developments in the field of VWD diagnosis, and consider how these advances can impact upon clinical diagnostic algorithms for use in routine clinical practice. In addition, we review some important recent advances pertaining to the various treatment options available for managing patients with VWD.

Background Accurate diagnosis of symptomatic low von Willebrand factor (VWF) remains a major challenge in von Willebrand disease (VWD). However, present tests do not adequately take into account flow forces that, at very high shear rates, reveal a weakness in the VWF-platelet glycoprotein glycoprotein Ib bond in normal subjects. The degree of this weakness is greater in symptomatic, but not asymptomatic, low VWF. Objective The aim of this study is to distinguish patients with symptomatic low VWF (levels in the 30–50 IU/dL range) from those with asymptomatic low VWF and normal subjects. Methods We measured platelet adhesion (PA)/aggregation in our novel microfluidic flow system that permits real-time assessment of PA (surface coverage) and PA/aggregation (V, aggregate volume) using epifluorescence digital videomicroscopy in flowing noncitrated whole blood at 4,000 second−1. Blood samples from 24 low VWF patients and 15 normal subjects were collected into plastic tubes containing 4 U/mL enoxaparin. MetaMorph software was used to quantify rates of PA and V increase. Results Rates of PA increase showed a bimodal distribution, with values for 16/24 patients (Group I) all below the 2.5th percentile of normal, and values for 8/24 patients (Group II) similar to controls. Bleeding scores (mean ± standard error) were 5.50 ± 0.45 versus 2.75 ± 0.45 (p = 0.00077), and 10 clinically significant bleeding events were observed in seven versus zero (p = 0.0295) Group I and Group II subjects, respectively. Conclusion The present approach may offer a definitive means to distinguish symptomatic low VWF from either asymptomatic low VWF or normal controls.

Background Data on the effect of ABO blood group (ABO), von Willebrand factor (VWF) levels, and age on factor VIII (FVIII) in non-severe haemophilia A (HA) is scarce. Objective To investigate if ABO, VWF levels, and age have an influence on the variability of FVIII levels and consequently on the assessment of severity in non-severe HA. Patients/methods Eighty-nine patients with non-severe HA and 82 healthy controls were included. Data on ABO was collected and FVIII clotting activity (FVIII:C) with one-stage clotting assay (FVIII:C OSA) and chromogenic substrate assay (FVIII:C CSA), FVIII antigen (FVIII:Ag) and VWF antigen (VWF:Ag) and activity (VWF:Act) were determined. Results In HA, FVIII:C OSA and CSA and FVIII:Ag were not different between non-O (n = 42, median 15.5, interquartile range 10.4-24.0; 10.0, 6.8-26.0 and 15.2, 10.7-24.9) and O (n = 47, 14.1, 9.0-23.0; 10.0, 5.0-23.0 and 15.2, 9.3-35.5), whereas in healthy controls, non-O individuals had significantly higher FVIII levels. Fviii C showed no relevant correlation with VWF levels in HA, but we observed strong correlations in healthy controls. Age had only a minor influence in HA, but had a considerable impact on FVIII:C in healthy controls. In multivariable regression analysis ABO, VWF:Ag and age were not associated with FVIII:C in HA, whereas this model explained 61.3% of the FVIII:C variance in healthy controls. Conclusions We conclude that in non-severe HA ABO and VWF levels do not substantially influence the variability of FVIII levels and age has only minor effects on it, which is important information for diagnostic procedures.