Specimen Requirement

Sodium citrate blue-top tube filled to the area filled to the indicator line on the side of the tube.

• Invert the sodium citrate tube end to end 4 times to thoroughly mix blood and anticoagulant. 
• Specimen should be routed to the laboratory as soon as possible. 
• Specimen is stable up to 4 hours at room temperature.
• If specimens cannot be routed to the laboratory within 4 hours of collection, the plasma should be removed from the cells and transferred to a plastic tube and frozen. 

• Precautions:

  • Do not collect specimens for anti-Xa testing from an arm with IV heparin running unless there is no other option.
  • It is not recommended to use a winged blood collection set (Butterfly).
  • If a vacuum tube butterfly must be used, the first tube in the series will be under-filled. Collect a “discard citrate tube”, and then collect the citrate tube used for testing. This will ensure the proper blood to anticoagulant ratio.
  • If using a syringe, use a blood transfer device to transfer blood from the syringe to the citrate tube within one minute of collection. Hold the syringe with the plunger in the up-right position and allow the vacuum present to fill the tube. Before collection, be sure the syringe plunger is pushed to the top of the syringe. The transfer device may pop up and needs to be held down to completely fill tube to between fill lines.
  • Do not “force fill” blood into a vacuum tube. This may result in activation of the platelets possibly leading to erroneous results. Allow the vacuum present to fill the tube. Do not remove vacuum tube cap to add blood.
  • Specimens should be obtained from a single venipuncture with minimal tissue trauma. Never combine multiple blood collections into a single vacuum tube.
  • Never re-use a syringe that was used for a pic line saline flush.