<b><span style='color:red'><u>VONRIS</span></u></b>


Ristocetin Co-factor - von Willebrand Factor - RAF - VWF Factor - R:CoF - von Willebrand Factor Activity - VWF

Specimen Collection Requirements


Whole Blood light blue top tube (3.2% Buffered Sodium Citrate)


For detailed specimen collection and handling, see Coagulation Specimen Collection Guidelines. If the patient is on medication, list the medications on the lab requisition. Call Special Coagulation Lab (503) 413-5119 for STAT requests, or minimal volume information. Due to short stability, whole blood specimen tubes must reach the testing department within 4 hours, otherwise submit frozen plasma aliquots. If submitting whole blood, transport at ambient temperature (15-25°C) in original unopened tube. If submitting frozen plasma aliquots, specimens must remain frozen (-20°C) during transport.

Preferred Volume

Two 2.7 mL whole blood or two 1.0 mL frozen plasma aliquots

Minimum Volume

One 2.7 mL whole blood or one 1.0 mL frozen plasma aliquot


Whole Blood: Ambient (15-25°C)
Plasma: Frozen (-20°C), aliquots must remain frozen during storage and transport

Rejection Criteria

Clotted samples, samples collected in containers other than 3.2% Buffered Sodium Citrate, tubes filled less than 90%, samples from patients with a Hematocrit greater than 55%, hemolyzed samples due to ex-vivo causes (i.e., difficult draw, poor sample draw), whole blood samples that were frozen before processing


WHOLE BLOOD Ambient: 4 hours. PLASMA: Ambient: 4 hours; Frozen: -20°C 2 weeks, -70°C 6 months

Testing Information


Tue, Thurs


Platelet Agglutination

Referral Lab

Legacy Laboratory Services

Reference Values

Reference Values

Varies, see report.

CPT Codes


Last Updated: Thursday, January 5, 2017 03:42:10 AM