Potential misdiagnosis of von Willebrand disease caused by insufficient mixing after thawing frozen plasma.

Introduction: von Willebrand disease (vWD) is a common inherited bleeding disorder caused by a deficiency in von Willebrand factor (vWF), but many laboratories and clinicians continue to struggle with diagnosing or excluding vWD. Its diagnosis requires laboratory testing, which may be compromised by preanalytical events, including poor specimen quality. This study assessed 17 different preanalytical conditions as potential causes of vWD misdiagnosis.

Methods: Specimens from healthy controls (N = 21) were obtained. vWF antigen and vWF activity were analyzed using a newly developed automatic coagulation analyzer according to various preanalytic conditions such as centrifugation conditions, storage room temperature before centrifugation, cold storage temperature after centrifugation, thawing conditions, and inadequate mixing of thawed citrated plasma following the recommendations of the Clinical and Laboratory Standards Institute (CLSI) H21-A5 guidelines.

Results: The only condition that was significantly different from the reference condition was lack of mixing after thawing frozen citrated plasma (vWF activity and antigen were reduced by 58.7% and 49.6%, respectively). Our study showed that mixing after thawing was more important than the chosen method of mixing.

Conclusion: Thawed plasma should be mixed because of the risk of misdiagnosing vWD. Further education regarding the importance of appropriate mixing is warranted to achieve results comparable to those of freshly centrifuged samples.