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Von Willebrand Factor Activity Ristocetin


TEST DIRECTORY
Test Name
Von Willebrand Factor Activity Ristocetin
Test Code
VWFActRis
SPECIMEN REQUIREMENTS
Specimen Requirements
Minimum of 4.0 mL frozen plasma, with 1.0 mL in each aliquot, for a total of 4 aliquots.
Supplies for Submission
Light Blue Top (5)
Specimen Collection

Patient should abstain from oral anticoagulant therapy (upon the advice of physician) for at least 2 weeks before collecting sample.

  1. Fill up each Light Blue Top tube as completely as possible and mix by gently inverting the tube 5-6 times.
    Inadequate filling will distort the exact ratio of 1 part sodium citrate to 9 parts blood required for accurate results.
  2. Immediately centrifuge the specimen at 1500 RCF for 15 minutes.
  3. Pipette the supernatant plasma and transfer to a plastic transport tube.
  4. Re-centrifuge plasma in the transport tube at 1500 RCF for 15 minutes to make sure that no red blood cells are present.
  5. Pipette the top two-thirds of the supernatant plasma and transfer ≥1.0 mL to a second transport tube (submit 4 tubes total), labeled with two patient identifiers.
  6. Label aliquot tube as citrate plasma and immediately freeze at -20 °C or lower for transport.
Storage Requirements
Critical Frozen (CFZ)
GENERAL AND TECHNICAL INFORMATION
Turn Around Time
12 days
CPT Code
85245