Specimen Collection Manual and Test Catalog

1 mL plasma aliquot for a single study. Samples requiring heparin neutralization require an additional 0.5 mL for each test.

• Ideally the patient should not be receiving anticoagulant medication as it may interfere with testing and cause erroneous results. See Anticoagulation Impact on Coagulation Tests.
• If the patient’s hematocrit (HCT) is >55%, the volume of anticoagulant in the tube should be adjusted. Contact a performing location for special tube preparation to reduce the citrate in the collection tube. For those patients with HCT >65.4% see LAB3632 Stago Sodium Citrate Adjustment Chart for formula to determine amount of citrate removal required.
• When possible, use fresh venipuncture to collect blood to avoid activation of coagulation by tissue thromboplastin. Blood may be drawn from an indwelling catheter or vascular access device. Draw sample from a lumen that has not been heparinized or flush the line with 5 ml of saline, and discard or use for other purposes the first 5-10 mL of blood.
• Tubes should be >90% filled.
• Immediately mix gently after collection by inverting the tube end over end 5 to 6 times. Avoid vigorous mixing or additional inversion. Observe for the presence of clots. Recollect if fibrin clots observed.
• Transport at ambient temperature to processing location and processing should be completed within 4 hours.
• Butterfly device collections, draw a discard tube first to remove air from collection tubing.

Centrifuge the citrated blue-top tubes immediately at designated time and speed to obtain platelet free plasma (<10,000/µL). Using a plastic pipette, carefully remove plasma from cells, avoiding platelet/buffy layer by leaving a thin layer of plasma on top the cells. The centrifuged plasma should be aliquoted (1 mL per aliquot) into clearly labeled polypropylene tubes. The number of tests ordered will determine the aliquots needed. Check the residual specimen for clot and if present discard sample and redraw specimen. Freeze upright and transport on dry ice.

Frozen.

Frozen: -20°C for 30 days, -70°C for 6 months. Room temperature: 4 hours.

Clotted specimen. Stability exceeded. Overfilled or underfilled tubes. HCT > 55% and anticoagulant ratio not adjusted. Note: Specimen suspected of thawing in transport, indicated by slant in aliquot or specimen in lid of tube, will have testing performed, and the comment “interpret results with caution as thawing suspected” added to results.

GMC: < 1 Bethesda Unit.

Inhibitor titer for specific factor.

Inhibitor for specific factor, FAIT, Antibody against coagulation factor, Bethesda titer

The factor inhibitor titer test is used to quantitate the level of a possible factor inhibitory antibody in a plasma sample. It is typically used to quantify Factor VIII and IX inhibitors, but it can be used with other coagulation factors. It should be considered when a mixing study shows an inhibitor is present with low factor activity.