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23028 Von Willebrand Factor Assay

Von Willebrand Factor Assay
Test Code: VWF
Synonyms/Keywords
​Ristocetin Cofactor, von Willebrand Factor Activity
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
*Platelet Poor Plasma 3.2% Citrated Blue Top Tube (BTT)​ 0.75 mL​ 0.75 mL​ 0.5 mL ​
Collection Processing Instructions
​One 0.75 mL citrated Blue Top Tube (BTT) plasma aliquot.
If more than one coagulation test is ordered, a separate aliquot is needed for each test.
-Collect in Citrated Blue Top Tube (BTT)
-Citrate anticoagulant must be adjusted for HCT >55%
-Tube must be at least 90% full
-Invert completely 3-4 times (without shaking) to mix
*See Instructions for: Preparation of Platelet Poor Plasma
Specimen Stability Information
Specimen Type Temperature Time
​Plasma ​Frozen ​6 months
Rejection Criteria
Clotted or Hemolyzed
​Contamination with IV or Hickman Line fluids
​Specimens that thaw during storage or transport
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Marshfield Tuesday and Friday ​Less than 2 hours Ristocetin co-factor activity, optical density/Siemens BCSXP​
Test Information
​Patients with blood group O have approximately 25% lower levels of von Willebrand factor and antigen. If the ABO blood group is not known on the patient, ABO blood typing is recommended to properly interpret the results of laboratory tests for von Willebrand's disease.
Contact Marshfield Labs Clinical Automated at 800-222-5835, ext. 16383 with pre-operative requests.
Reference Range Information
Performing Location Reference Range
​Marshfield 38-170%
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​85245
Synonyms/Keywords
​Ristocetin Cofactor, von Willebrand Factor Activity
Ordering Applications
Ordering Application Description
​Centricity ​Von Willebrand Factor Assay
​Cerner ​Von Willebrand Factor Assay
​COM ​Von Will Factor Assay
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
*Platelet Poor Plasma 3.2% Citrated Blue Top Tube (BTT)​ 0.75 mL​ 0.75 mL​ 0.5 mL ​
Collection Processing
​One 0.75 mL citrated Blue Top Tube (BTT) plasma aliquot.
If more than one coagulation test is ordered, a separate aliquot is needed for each test.
-Collect in Citrated Blue Top Tube (BTT)
-Citrate anticoagulant must be adjusted for HCT >55%
-Tube must be at least 90% full
-Invert completely 3-4 times (without shaking) to mix
*See Instructions for: Preparation of Platelet Poor Plasma
Specimen Stability Information
Specimen Type Temperature Time
​Plasma ​Frozen ​6 months
Rejection Criteria
Clotted or Hemolyzed
​Contamination with IV or Hickman Line fluids
​Specimens that thaw during storage or transport
Reference Range Information
Performing Location Reference Range
​Marshfield 38-170%
For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Marshfield Tuesday and Friday ​Less than 2 hours Ristocetin co-factor activity, optical density/Siemens BCSXP​
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​85245
For most current information refer to the Marshfield Laboratory online reference manual.