VWFX - Specimen: von Willebrand Factor Activity, Plasma

Test Catalog

Test Name

Test ID: VWFX    
von Willebrand Factor Activity, Plasma

Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.

If von Willebrand factor activity is <55%, then the von Willebrand factor ristocetin cofactor activity assay will be performed at an additional charge.

 

MCF internal patients: von Willebrand factor activity results <55% will not reflex ristocetin cofactor unless ordered as part of von Willebrand profile. Recommend von Willebrand profile testing if not previously performed.

Specimen Type Describes the specimen type needed for testing

Plasma Na Cit

Additional Testing Requirements

Tests for F8A / Coagulation Factor VIII Activity Assay, Plasma and VWAG / von Willebrand Factor Antigen, Plasma are recommended in conjunction with von Willebrand activity.

Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.

See Coagulation Studies in Special Instructions.

 

Specimen Type: Platelet-poor plasma

Collection Container/Tube: Light-blue top (citrate)

Submission Container/Tube: Polypropylene vial

Specimen Volume: 2 mL in 2 vials each containing 1 mL

Collection Instructions:

1. Specimen must be drawn prior to factor replacement therapy.

2. Spin down, remove plasma, and spin plasma again.

3. Freeze specimens immediately at < or =-40 degrees C, if possible.

4. Send specimens in the same shipping container.

Additional Information:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

2. Each coagulation assay requested should have its own vial.

Forms

If not ordering electronically, complete, print, and send a Coagulation Test Request Form (T753) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/coagulation-test-request-form.pdf)

Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.

0.5 mL

Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross reject

Icterus

NA

Other

NA

 

Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.

Specimen TypeTemperatureTime
Plasma Na CitFrozen14 days