Von Willebrand Screen

General Information

Test Availability:

VWF Screening is available at Queen Elizabeth and Heartlands sites. Note samples for collagen binding are sent to Queen Elizabeth laboratory. 

For urgent special coagulation assay information click Here

 External Requests:

Note: For external requests please click Here for Coagulation Disorders request form. Please complete all information fully.

Sample packing and transportation:

Frozen plasma should be sent on dry ice using an insulated container to ensure that it remains frozen during transport. Please refer to the preanalytical variables section of the BSH guidelines on the laboratory aspects of assays used in haemostasis and thrombosis¹.

As an alternative the bio-freeze container system can be used to ensure samples remain frozen in transit. These have been locally validated to maintain samples at -20^oC for up to 12 hours  providing they have been preconditioned in a -80^oC freezer for 24 hours prior to use.

Disclaimer:

Please note failure to use an appropriate transit container may affect sample integrity, thus the accuracy of results cannot be guaranteed.  Furthermore, samples packaged incorrectly that arrive in a thawed state cannot be tested.

Please contact the laboratory on 0121 371 5988 (Queen Elizabeth Hospital) or 0121 424 0908 (Heartlands Hospital) if you require any further information.

1) Baker, P., Platton, S., Gibson, C., Gray, E., Jennings, I., Murphy, P., Laffan, M. and British Society for Haematology, Haemostasis and Thrombosis Task Force (2020), Guidelines on the laboratory aspects of assays used in haemostasis and thrombosis. Br. J. Haematol., 191: 347-362.

https://doi.org/10.1111/bjh.16776

Samples that meet the following criteria will not be processed:

• Haemolysed, clotted, underfilled or overfilled samples.
• Samples >12 hours old from the time of collection.
• Samples received from other hospital laboratories that have been frozen and thawed.
• Samples which fail the minimum data set.

Assay Limitations:

VWF:Ag and VWF:RCo:

• VWF results may be affected by bilirubin above 14mg/dl and triglycerides above 1500mg/dl.
• The presence of Rheumatoid factor may produce and overestimation of the test result.
• VWF is an acute phase protein and may be elevated above baseline in a variety of conditions including inflammation, stress, exercise, liver disease, pregnancy or oestrogen therapy. These conditions may obscure diagnosis of the milder forms of von Willebrand disease (vWD). Repeat testing may be indicated.
• Lipaemic samples may lead to an underestimation of the VWF:RCo result.

 VWF:CBA:

• vWF:CBA levels vary considerably in any individual. They can be falsely elevated due to many reasons such as stress, exercise, smoking, pregnancy, oral contraception, infection and chronic liver disease.  It is important to have the patient relaxed before taking samples for this assay and also to be aware of their clinical circumstances for correct interpretation of results.
• Reduced levels of vWF:CBA are associated with blood group O.