• Ideally, the patient should not be on anticoagulant therapy
• Avoid warfarin (Coumadin®) therapy for two weeks prior to the test and heparin, direct Xa, and thrombin inhibitor therapies for about three days prior to testing

Lt blue Sodium citrate (NaCit) - 2.7mL

• If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted.
• Do not draw from an arm with a heparin lock or heparinized catheter
• Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.
• The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood.
• A discard tube is not required prior to collection of coagulation samples unless the sample is collected using a winged (butterfly) collection system.
  • With a winged blood collection set a discard tube should be drawn first to account for the dead space of the tubing and prevent under-filling of the evacuated tube.
• When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes.
• Any tube containing an alternative anticoagulant should be collected after the blue-top tube.
• Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes.

1. Spin
2. Transfer 1.0 mL plasma to a Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp), labelled as Na cit plasma
3. Freeze

Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp)

Frozen - 28 days

Freeze/thaw cycles - stable x3

• Gross hemolysis
• Clotted specimens
• Specimens that have thawed in transit
• Improperly labeled specimens

Prothrombin Time (PT)-based one-stage clotting time assay. Factor VII- depleted plasma is used as the substrate and the substrate and the clotting time with the patient plasma is compared to the clotting time of normal pooled plasma.

51 - 186%

Direct Xa or thrombin inhibitor therapy may cause factitiously low results.