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Lab Dept:
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Coagulation
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Test Name:
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VON WILLEBRAND SCREEN
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General Information
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Lab Order Codes:
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VWS
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Synonyms:
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See individual test listings, links can be found under Reference Range
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CPT Codes:
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85240 - Clotting; factor VIII (AHG), one stage
85245 - Factor VIII vW Factor, Ristocetin cofactor
85246 – Factor VIII vW antigen factor
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Test Includes:
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Factor VIII, Ristocetin Cofactor and von Willebrand antigen reported as a % and Ristocetin Cofactor:VW Antigen Ratio.
A specimen will be held for possible multimer analysis, please contact Pathology at 612- 813- 6711 for consultation. Tubes will be held for one month.
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Logistics
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Test Indications:
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Useful for diagnosis (or exclusion) of von Willebrand’s disease or trait.
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Lab Testing Section:
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Coagulation (Minneapolis Campus)
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Phone Numbers:
Minneapolis:
Saint Paul:
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612-813-6280
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651-220-6550
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Test Availability:
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Twice Weekly (Tuesday and Friday)
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Turnaround Time:
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3 – 5 Days
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Special Instructions:
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See Patient Preparation
Deliver immediately to the laboratory at room temperature. Indicate when specimen is drawn from a line or a heparin lock.
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Specimen
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Specimen Type:
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Whole blood
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Container:
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Light Blue (Buffered Na Citrate 3.2%) top tubes
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Draw Volume:
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8.1 mL blood (into three 2.7 mL tubes) Minimum: 5.4 mL blood (into two 2.7 mL tubes)
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Processed Volume:
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2.7 mL (Minimum: 1.8 mL) plasma
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Collection:
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A clean venipuncture is essential.
If the patient’s hematocrit is >55%, call the laboratory for a special tube.
Fill tube completely.
Mix thoroughly by gentle inversion.
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Special Processing:
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Lab Staff: All testing will be performed in Minneapolis.
St. Paul Lab: Send whole blood specimens to Mpls for processing via courier. Must be processed within 4 hours of collection. Contact Mpls prior to sending.
Mpls Lab: Centrifuge specimen, remove plasma sample taking care not to disturb buffy coat. Perform a second spin after removing plasma from the original collection containers. Aliquot into two screw top plastic vials (Minimum: 0.5 mL in each). Store frozen at -70 degrees C (one vial in “VWS to be completed” cup and the other in the “von Willebrand Multimer Testing” cup for potential multimer analysis) temperatures.
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Patient Preparation:
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No Heparin for 2 days prior to testing.
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Sample Rejection:
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Improper tube; clotted sample; underfilled tube; mislabeled or unlabeled specimens
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Interpretive
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Reference Range:
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See individual tests for specific reference ranges:
von Willebrand Antigen
Factor VIII Assay
Ristocetin Cofactor
For further interpretation of results or questions regarding Multimer analysis, please contact Pathology at 612- 813- 6711.
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Critical Values:
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N/A
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Limitations:
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See individual test listings, links can be found under Reference Range
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Methodology:
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See individual test listings, links can be found under Reference Range
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References:
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See individual test listings, links can be found under Reference Range
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Updates:
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5/24/2010: Tubing patient specimens is no longer prohibited.
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