Specimen Requirements

If incubation is required, PT/PTT must be specified and incubation times will be the initial test followed by 30-, 60-, 90-, and 120 minutes at 37° C.

1. Draw blood in a blue-top (citrate) tube(s). Spin down, remove plasma, spin plasma again, and place 0.5 mL of citrate platelet-poor plasma in plastic vial. (Glass vial is not acceptable.)

Note:  Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.
2. If test is not performed immediately, send specimen frozen.
Note:  1. Indicate Prothrombin Time (PT) or Partial Thromboplastin Time (PTT) Mixing Study on request form.

2. Each coagulation assay requested should have its own vial.