Do not draw from an arm with a heparin lock or heparinized catheter.
Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. 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.
When non-citrate tubes are collected for other tests, collect sterile and non-additive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternate 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
Immediatley following collection, mix sample thoroughly by gentle inverting 8 - 10 times, to prevent clotting