Among women with suspected bleeding disorders who were tested for von Willebrand Disease (VWD), significant discrepancies between onsite and off-site processing were found in von Willebrand Factor (VWF) samples that were collected and assayed. These findings suggest that VWF assays should be collected and processed in 1 location and monitored by a hematologist, according to study results published in the American Journal of Hematology.

Julie Jaffray, MD, of the Children’s Hospital Los Angeles in California, and associates conducted a retrospective study at 17 institutions that are part of The Foundation of Women and Girls with Blood Disorders, Learning Action Network, to assess the number of post-menarchal women with inconsistent VWF testing results between off-site and onsite processing.

A total of 263 women, aged 12 to 50 years (median age, 15 years), were included in the analysis. The majority (72%) of women were referred for testing by a physician because of heavy menstrual bleeding, followed by easy bruising (37%), and epistaxis (30%). Primary care physicians and obstetricians/gynecologists were the most frequent referrers (63% and 24%, respectively). At the time of consultation, 38% of women were on hormonal contraception.

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Nearly all participants had VWF antigen (VWF:Ag) processing in an onsite and off-site location (95%); VWF ristocetin cofactor (VWF:RCo) and factor VIII (FVIII) samples were processed off-site and onsite for 84% and 87% of women, respectively.

Low VWF:Ag was reported in 38% of samples processed off-site and 22% of those processed onsite. Similarly, VWF:RCo and FVIII levels were confirmed lower in off-site processing compared with onsite processing (VWF:RCo, 55% vs 32%, respectively; FVIII, 29% vs 13%, respectively). Of note, 33% of women had normal or elevated VWF:Ag and/or VWF:RCo before their hematology consultation.

While the authors acknowledged that VWF variation within an individual is possible, ultimately, less than half of the participants were diagnosed with VWD or low VWF; 39% of women had normal hemostatic evaluations.

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The investigators noted that heavy menstrual bleeding has been recognized as a symptom of an underlying bleeding disorder, which has led to an increase in evaluation, diagnosis, and treatment of bleeding disorders in this population.

“These results highlight the need for VWF testing to ideally be both drawn and processed with little delay at laboratories with onsite processing under the guidance of a hematologist,” the authors concluded.


Jaffray J, Staber JM, Malvar J, et al. Laboratory misdiagnosis of von Willebrand Disease in post-menarchal females: a multi-center study [published online May 17, 2020]. Am J Hematol. doi: 10.1002/ajh.25869