DILUTE RUSSELL'S VIPER VENOM TIME (089-0526)

Synonyms: DRVVT, DRVVC, Dilute Russell's Viper Venom Test, Lupus Panel

CPT Code(s):  85613 

Test Order Mnemonic:  DRVVT

Applies To: Component of the Lupus Panel.  DRVVT Check screens for Lupus-like anticoagulants (anti-phospholipid antibodies).  DRVVT Check/Sure ratio confirms presence of Lupus Anticoagulants in plasma.

Request Form:  Hematology A

Collection: Routine venipuncture; discard 1st mL of blood or collect other tubes (EDTA, red-topped) prior to collecting sample in blue-topped (citrate) tube.

Storage Instructions: Viable for 4 hours at room temperature.   If time from draw to receipt in the laboratory is to be greater than 4 hours, double centrifuge the specimen; remove the plasma from red cells and snap freeze (-70°C) plasma. Snap frozen plasma is viable for up to six months.

Causes for Rejection: QNS, clotted, severely hemolyzed, specimen greater than 4 hours old, wrong tube (3.8% sodium citrate), identification error, sample processed/transported and/or stored improperly.

Availability: Samples are accepted 24 hours per day at Sample Management, 5.136 McCullough Bldg.

Turnaround Time: 7 days (call lab for schedule)

Special Instructions: Deliver sample to lab within ½ hour for best results. Accepted up to 4 hours from draw.

Specimen: Blood

Volume: 4.5 mL blood

Container:  3.2% Sodium citrate tube (light blue top tube)

Reference Range:  DRVVT Check:   £ 44.1 seconds = No significant evidence of Lupus Anticoagulant

                               DRVVT Check/Sure Ratio:   £ 1.2  = Negative (No significant evidence of Lupus  Anticoagulant)

Test Methodology: Screening test (DRVVT Check) is performed using the Electromechanical viscosity detection system.  If result is >44.1 seconds, a second test is performed, this time with an excess of phospholipids to neutralize any remaining Lupus Anticoagulant (DRVVT Sure). The ratio Check /Sure is then calculated.

In accordance with the SSC Subcommittee for the Standardization of LA guidelines, results should be compared to other established LA tests performed on the same sample, as no single assay can guarantee with certainty that LA is present or absent in test samples.

Interfering Substances:   Anticoagulant therapy (Heparin >1 IU/ml, Coumadin); extremely high levels of hemoglobin, bilirubin or lipids; gross hemolysis.  Patients with deficiencies of Factors II, V, or X, or patients on oral anticoagulant therapy (OAT) may exhibit prolonged results.  However, the final ratio (DRVVT/DRVVC) should be normal unless LA is present.  False positive results have been known to infrequently occur with patient on OAT. It is recommended that testing not be done on patients receiving OAT until having been off coumadin for 2 weeks.  Plasma containing heparin levels greater than 1.0 U/ml may give false positive results, and should not be tested with these reagents.

Reviewed 10/11/07 by W. Russo, MT(ASCP)