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Alias Names: RVVT RATIO
Methodology: Photo-Optical Clot Detection
Edit Date: 6/6/2008
Performed: Monday, Thursday
Released: Weekly
CPT Code: 85597
Specimen Collection Details
Collection: One 4.5 mL light blue top tube (sodium citrate). Collect by careful venipuncture to avoid tissue fluid contamination or hemolysis. Do not use needles smaller then 23 gauge. Fill tube to maximum draw, at least 90% full. Mix by gentle inversion.
Handling: Due to short stability, specimen must be either sent STAT to arrive at the laboratory within 4 hours, or sent frozen. For STAT, refrigerate and keep capped in original tube. Call for STAT pick-up. 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 a plastic vial. Label with patient name, I.D. number, test, and “citrated plasma.” Freeze immediately. Send to PeaceHealth Laboratories within 7 days. If multiple tests are ordered, freeze a separate aliquot for this test.
Stability: 4 hours refrigerated, or 7 days frozen.
Standard Volume: 4.5 mL whole blood or 2 mL plasma.
Minimum Volume: 1.8 mL whole blood or 0.5 mL plasma.
Transport: Original tube refrigerated if sent STAT; citrated plasma frozen on dry ice in a Styrofoam container.
Comments: It is essential that plasma be truly ‘platelet-poor’ prior to freezing in order to prevent neutralization of lupus anticoagulants by platelet phospholipids. It is advisable to periodically check the platelet count of ‘platelet-poor plasma’ in your lab to assure that the count is consistently below 15,000/cumm. If not, centrifuge time and/or speed should be increased. See also: Coagulation Study, Anti-Phospholipid Panel (25620) and Coagulation Study, Lupus Inhibitor Panel (25610).
Rejection Criteria: Visible fibrin; moderate to marked hemolysis; specimen received in laboratory beyond stated stability.

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