Establishment of an International Reference Reagent for standardization of von Willebrand factor binding to recombinant glycoprotein Ib (VWF:GPIbM and VWF:GPIbR): Official Communication of the SSC

Diagnostic Testing for von Willebrand Disease: Trends and Insights from North American Laboratories over the Last Decade

Accurate diagnosis of von Willebrand disease (VWD) depends on the quality, precision, and variability of the laboratory assays. The North American Specialized Coagulation Laboratory Association (NASCOLA) is a provider of external quality assessment (EQA) for approximately 60 specialized coagulation laboratories in North America. In this report, NASCOLA EQA data from 2010 to 2021 are reviewed for trends in methodology and precision among various assays. In particular, recent ASH ISTH NHF WFH (American Society of Hematology, International Society on Thrombosis and Haemostasis, National Hemophilia Foundation, and World Hemophilia Federation) guidelines for diagnosis of VWD are reviewed in light of EQA data. In contrast to other geographic regions, laboratories in North America predominantly use three-assay screening panels (antigen, platelet-binding activity, and factor VIII [FVIII] activity) rather than four-assay panels (antigen, platelet-binding activity, FVIII activity, and collagen-binding activity). They also use latex immunoassays rather than chemiluminescence immunoassays, and the classic ristocetin cofactor (VWF:RCo) assay and monoclonal antibody (VWF:Ab) assay to assess VWF platelet-binding activity over newer recommended assays (VWF:GPIbM and VWF:GPIbR). Factors that may be influencing these North American practice patterns include lack of Food and Drug Administration approval of the VWF:GPIbM, VWF:GPIbR, collagen binding assays, and chemiluminescence methodologies, and the influence of the 2008 National Heart, Lung, and Blood Institute guidelines on laboratory practice. Lastly, systems-based solutions are urgently needed to improve the overall accuracy of laboratory testing for VWD by minimizing preanalytical variables and adopting assay standardization.

Case-based discussion on the implications of exogenous estrogens in hemostasis and thrombosis: the hematologist's view

In the childbearing years, hormonal therapy or hormonal changes in the menstrual cycle or the puerperium may be complicated by bleeding or thrombosis; however, among women with congenital disorders of hemostasis and thrombosis, the risk of bleeding or thrombosis may be increased. In women with congenital bleeding disorders, heavy menstrual bleeding is the most common bleeding symptom, and postpartum hemorrhage occurs despite treatment. Given the limitations of current therapy and the associated medical and psychological burden in women with bleeding disorders, better treatment approaches are needed to improve health outcomes and quality of life. In women with congenital thrombotic disorders, thromboembolism may complicate exogenous hormonal therapy and endogenous hormonal change during pregnancy and procedures, but risk differs by type of thrombophilia, procedure, time at risk, and thrombosis risk factors, all of which affect management. In this article, I shall consider a case-based discussion of current issues in women with congenital bleeding and clotting disorders, including heavy menstrual bleeding in a woman with VWD, postpartum hemorrhage risk in VWD, and thrombosis risk with oocyte retrieval in a woman with factor V Leiden and past thromboembolism. The goals are to review bleeding or thrombosis risk in these cases, current data, limitations of current treatment guidelines, and areas for future study.