von Willebrand's Factor Investigations

Department of Haematology

Notes

A full von Willebrand's investigation consist of the following assays:

• Clotting Screen (performed at GRH or CGH)
• Factor VIII assay (performed at GRH or Oxford Haemophilia Centre)
• Von Willebrand screen

The von Willebrand Screen consists of:

• von Willebrand Factor - Collagen Binding Assay (CBA)
• von Willebrand Antigen test
• Innov VWF: GP1bM - von Willebrand Factor activity by Glycoprotein 1b Binding Assays

(performed at Oxford Haemophilia centre)

Sample Requirements

3 x 3ml or 3.5ml Trisodium Citrate samples (for Clotting Screen, Factor VIII, Ricof and von Willebrands assays)

For paediatric requests please contact the laboratory for advice.

Turnaround Times

Up to 6 weeks for all investigations to be completed

Sample Storage and Retention

• Pre analysis storage: do not store, send to laboratory within 2 hours, if possible
• Sample retention by lab: Citrate samples are retained for a minimum of 24 hours at 15-30°C. If specialist coagulation tests are requested, one or more aliquots may be frozen until analysis (or up to two months) at between -15 and -40°C. After analysis, these samples will be retained for a further 24 hours at 15-30°C.

It may be possible to add these tests on to a previous request as long as there were sufficient samples and the samples are less than 4 hours old (if not already frozen).

Reference Ranges

Please click for Clotting Screen and Factor VIII ranges.