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Alias Names: Von Willebrand Panel
Methodology: Mechanical Clot Detection / Immuno-Turbidometric Assay / Ristocetin-induced PLT aggregation using normal platelets and patient plasma
Edit Date: 6/6/2008
Components: Factor VIII Activity / Von Willebrand Factor Antigen (VWF:Ag) / Von Willebrand Factor Ristocetin Cofactor (VWF:RCo)
Performed: Wednesday (interpretation and reporting by next day)
Released: 7 days
CPT Code: 85240 / 85244 / 85245
Specimen Collection Details
Collection: Two 4.5 mL light blue top tubes (sodium citrate). Collect by careful venipuncture to avoid tissue fluid contamination or hemolysis. Do not use needles smaller than 23 gauge. Fill tubes to maximum draw (at least 90% full). Mix by gentle inversion. Call the Special Coagulation Department (541-687-2134 x4612) when urgent testing is needed in order to assure STAT testing.
Handling: Due to short stability, specimen must either be sent STAT to arrive in laboratory within 4 hours, or sent frozen. For STAT, refrigerate and keep capped in original tubes. For standard delivery, centrifuge to produce platelet poor plasma (at least 1700 X G for 15 minutes) and using a plastic pipette, transfer the top 2/3 of the plasma into 3 plastic vials. Label with patient name, I.D. number, test, and “citrated plasma.” Freeze immediately. Send to the laboraory within 7 days. If multiple tests are ordered, freeze a separate aliquot for this test.
Stability: 4 hours ambient or refrigerated, or 7 days frozen.
Standard Volume: Two 4.5 mL whole blood or 2 mL plasma.
Minimum Volume: Two 2.7 mL whole blood or 1 mL plasma.
Transport: Original tubes refrigerated if STAT, or citrated plasma frozen on dry ice.
Comments: Von Willebrand Factor is an acute phase reactant which may become elevated secondary to pregnancy, infection, or inflammation. Screening for VW Disease should be avoided during these conditions, since lab abnormalities may correct to within normal range due to the acute phase response.
Rejection Criteria: Visible fibrin; moderate to marked hemolysis; specimen received in laboratory beyond stated stability.

Pathologist interpretation accompanies report.

PeaceHealth Laboratories