Clinics and Departments

Laboratory Services

Lab Dept:

Coagulation

Test Name:

VON WILLEBRAND SCREEN

General Information

Lab Order Codes:

VWS

Synonyms:

See individual test listings, links can be found under Reference Range

CPT Codes:

85240 - Clotting; factor VIII (AHG), one stage
85245 - Factor VIII vW Factor, Ristocetin cofactor
85246 – Factor VIII vW antigen factor

Test Includes:

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.

Logistics

Test Indications:

Useful for diagnosis (or exclusion) of von Willebrand’s disease or trait.

Lab Testing Section:

Coagulation (Minneapolis Campus)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Twice Weekly (Tuesday and Friday)

Turnaround Time:

3 – 5 Days

Special Instructions:

See Patient Preparation

Deliver immediately to the laboratory at room temperature. Indicate when specimen is drawn from a line or a heparin lock.

Specimen

Specimen Type:

Whole blood

Container:

Light Blue (Buffered Na Citrate 3.2%) top tubes

Draw Volume:

8.1 mL blood (into three 2.7 mL tubes) Minimum: 5.4 mL blood (into two 2.7 mL tubes)

Processed Volume:

2.7 mL (Minimum: 1.8 mL) plasma

Collection:

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.

Special Processing:

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.

Patient Preparation:

No Heparin for 2 days prior to testing.

Sample Rejection:

Improper tube; clotted sample; underfilled tube; mislabeled or unlabeled specimens

Interpretive

Reference Range:

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.

Critical Values:

N/A

Limitations:

See individual test listings, links can be found under Reference Range

Methodology:

See individual test listings, links can be found under Reference Range

References:

See individual test listings, links can be found under Reference Range

Updates:

5/24/2010: Tubing patient specimens is no longer prohibited.



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