Preparation of Platelet Poor Plasma for Coagulation testing

Materials needed: disposable transfer pipettes, 2 plastic tubes (that will not crack when frozen), caps, labels.

  1. Process tube immediately: Must be spun within one hour of collection for PTT (on heparin) and HEPXA.
    1. Evaluate specimen before processing:
      1. Verify proper collection tube- blue-top.
      2. Check tube is properly filled. (see test directory link for proper fill example)
      3. Invert tube gently to look for clots
  2. Centrifuge (spin) tubes in centrifuge approved for Coag tube testing (validated for platelet poor plasma). Use designated setting for coag tubes.
  3. Evaluate spun tube acceptability:
    1. Check hematocrit: acceptable hematocrit is between <55%.
      1. If cells appear >1/2 tube volume, contact lab Coag dept to confirm and supply special recollection instructions/tubes.
    2. Check for hemolysis. Contact lab Coag dept or procedure to confirm acceptability against hemolysis chart.
  4. Remove Plasma:
    1. Do NOT disturb the cell layers.
    2. Remove the top ¾ of plasma into labeled plastic tube using transfer pipette. Leave about 0.5ml plasma over the cell layers
      1. NOTE: Do NOT pour plasma off from cells.
    3. Check cell layers for a clot, by inserting two wooden sticks, swirl and look for clot on sticks. If clotted. Redraw specimen.
    4. Keep original tube for 24 hours for verification, if needed.
  5. Spin removed plasma tube: (to confirm platelet poor)
    1. Carefully remove plasma tube after centrifugation to not disturb and sediment.
    2. Transfer plasma to a second plastic tube, using transfer pipette. Do NOT disturb bottom of tube (about 0.5ml). Label sample with test label and include ‘plasma-blue tube’.
    3. Sample volume for testing: 1ml frozen plasma. (minimum 0.5ml)
    4. Promptly freeze, <20°C. Freeze for 1 hour prior to transport.
      1. Transport immersed in Dry Ice to PRMC. Must not thaw during transit. Verify courier is packing in dry ice.