Specimen Requirements

Draw blood in a light blue-top (3.2% sodium citrate) tube(s), and send 4.5 mL of sodium citrate whole blood. (Clotted or visibly hemolyzed specimen, specimen drawn in wrong tube, or tube that has less than expected fill is not acceptable.)
Note:  1. Mix 9 parts of freshly drawn blood with 1 part of 3.2% sodium citrate anticoagulant. Invert tube gently 3 to 4 times immediately after venipuncture to ensure proper mixing of blood and anticoagulant.

2. If blood is drawn through an indwelling catheter, flush line with 5 mL of saline. Discard first 5 mL of blood or 6 dead space volumes of catheter or use for other laboratory tests.

3. If blood is drawn with a butterfly set, a waste tube must be drawn to eliminate dead space of tubing to ensure adequate blood is drawn into coagulation tube.

4. 3.2% sodium citrate concentration must be adjusted in patients who have hematocrit values >55%.

5. Plasma from a nonheparinized patient should be tested within 4 hours of draw (centrifuged or uncentrifuged) if stored in an unopened tube at room temperature. Plasma from a heparinized patient must be centrifuged within 1 hour of draw and tested within 4 hours. If the plasma cannot be tested within 4 hours, spin down, remove plasma, and spin again. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.  If there is a delay in testing greater than these limits, freeze specimen in plastic vial. A frost-free freezer should not be used because of the freeze/thaw cycles.

Unspun specimens must be transported at ambient temperature and arrive at the laboratory within one hour of draw.