Haematology

Preferred Sample Type

Von Willebrand Screen

Von Willebrand Screen

Specimen Volume

3 x 3.5ml

Specimen Transport

Standard transport to laboratory - State for the attention of Special Coagulation on request form

Sample Preparation

Samples for any coagulation tests must be filled to the black fill line indicated on the sample tube. Any sample filled above or below this level will be rejected and a repeat sample will be required

Turnaround Time

21 days

Sample Processing In Laboratory

Sample should be centrifuged

Sample Stability

12 hours from venepuncture (ideally received no later than 4 hours after collection)

General Information

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

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.

Reference Range

Factor VIII 57-158 u/dL

von Willebrand Factor Antigen (VWF:Ag) 48-175 u/dL

von Willebrand Factor Activity (VWF:RCo, RICOF) 47-154 u/dL

von Willebrand Factor Collagen Binding activity (vWF:CBA) 57-164 IU/dL

Specifications

  • EQA Status: NEQAS
  • EQAS Scheme: Yes

Creation Date

Monday, 08 August 2011

Modification Date

Thursday, 27 July 2023

General Information

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Protection of Personal Information – Clinical Laboratory Services comply with the Trust Data Protection Policy and have procedures in place to allow the Directorate and it’s employees to comply with the Data Protection Act 1998 and associated best practice and guidance.

University Hospitals Birmingham medical laboratories at Queen Elizabeth Hospital, Heartlands Hospital, Good Hope Hospital and Solihull Hospital are UKAS (United Kingdom Accreditation Service) accredited to the ISO 15189:2012 standard. For a list of accredited tests and other information please visit the UKAS website using the following link: https://www.ukas.com/find-an-organisation/

  • Molecular Pathology is a UKAS accredited medical laboratory No. 8759
  • Biochemistry is a UKAS accredited medical laboratory No. 8910
  • Haematology and Transfusion is a UKAS accredited medical laboratory No. 8784
  • Clinical Microbiology is a UKAS accredited medical laboratory No. 8760
  • Cellular Pathology is a UKAS accredited medical laboratory No. 10141
  • Musculoskeletal laboratory is a UKAS accredited medical laboratory No. 9897
  • Heartlands, Good Hope and Solihull Hospital pathology laboratories are a UKAS accredited medical laboratory No.8217.

Tests not appearing on the UKAS Schedule of Accreditation currently remain outside of our scope of accreditation. However, these tests have been validated to the same high standard as accredited tests and are performed by the same trained and competent staff.

For further test information, please visit the test database: http://qehbpathology.uk/test-database

For further information contact Louise Fallon, Quality Manager, 0121 371 5962