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VWSCR
VON WILLEBRAND SCREEN W/O PLATELET AGGREGATION STUDIES

Test Code VWSCR 
Test VON WILLEBRAND SCREEN W/O PLATELET AGGREGATION STUDIES 
Description Factor VIII
Von Willebrand Factor Assay (Ristocetin Co-Factor Assay)
Von Willebrand Factor Antigen
(Tests may be ordered individually) 
Specimen Collect specimen as follows:
1. Draw blood in a light blue-top (3.2% sodium citrate) tube (s). Separate plasma from cells within 1 HOUR of collection in a centrifuge at 2,500 rpm for 15 minutes or 3,000 rpm for 10 minutes.
NOTE: Double-centrifuged specimens are critical for accurate results as platelet contamination may cause spurious results.
2. Using a plastic transfer pipette (do not use glass pipette) decant the plasma to a screw-capped, plastic (polypropylene) vial. (Glass vials will not be accepted.)
3. Divide the specimen into as many 0.5 - 1.0 mL aliquots as possible and cap the vial(s) tightly.
4. Freeze specimen(s) immediately at <= -40 C.
5. Send specimens(s) FROZEN on dry ice.

NOTE:
1. SPECIMENS WILL BE REJECTED IF UNDERFILLED (<90%), CLOTTED, HIGH HEMATOCRIT (>55%), OR GROSSLY HEMOLYZED.
2. Follow "Special Procedure for Drawing Specimen from an A-line". 

Reference Values An interpretive report will be issued. 
Analytic Time 14 - 21 Days 
CPT Code(s) 85240  Factor VIII
85245  Von Willebrand Factor Assay, Plasma (Ristocetin Co-Factor)
85246  Von Willebrand Factor Antigen, Plasma (VWFAG)