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Dilute Russell Viper Venom Time
MessageLabCorp
Test Code
117887
CPT Codes
85613
Preferred Specimen
"Plasma
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Minimum Volume
"1 mL
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Instructions
"If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted. Refer to Coagulation Collection Procedures for directions.
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Transport Container
"Blue-top (sodium citrate) tube
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Transport Temperature
frozen
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
"Gross hemolysis; clotted specimen; frozen specimen thawed in transit; tubes <90% full; improper labeling; specimen collected in tube other than 3.2% citrate
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Methodology
"Low phospholipid reagent consisting of Russell viper venom with excess calcium is mixed with patient plasma. The time to clot formation is measured photo-optically. "
Limitations
"The dRVVT may be prolonged in patients with deficiencies or inhibitors of factors X, V, II, and fibrinogen. Patients on warfarin will have extended dRVVT results.7 Plasma heparin levels >1 IU/mL may interfere with this test.8 Platelets are a rich source of phospholipid that can neutralize LA. Improper preparation of the platelet-poor plasma at collection reduces the sensitivity of this assay for LA. Due to the heterogeneity of LA antibodies, no single assay will identify all cases.
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