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 than 23 gauge. Fill tube to maximum draw, at least 90% full. Mix by gentle inversion.
Due to short stability, specimen must either be sent STAT to arrive in laboratory within 4 hours, or send frozen. If STAT, refrigerate and keep capped in original tube. Call for STAT pick-up. For standard delivery, centrifuge to produce platelet poor plasma, and using a plastic pipette, transfer plasma to a plastic tube. Label with patient name, I.D. number, test, and “citrated plasma.” Freeze immediately. Send to the laboratory within 7 days. If multiple tests are ordered, freeze a separate aliquot for this test.
4 hours ambient or refrigerated, or 7 days frozen.
4.5 mL whole blood or 2 mL plasma.
1.8 mL whole blood or 0.5 mL plasma.
Original tube refrigerated if STAT, or citrated plasma frozen on dry ice.
Patient must not be receiving unfractionated heparin. Heparin will interfere with clot-based factor assays.
Visible fibrin; moderate to marked hemolysis; specimen received in laboratory beyond stated stability.