Specimen Requirements

Submit only 1 of the following specimens:

Riverside Inpatient and Riverside Campus draw sites:

Testing must be performed within 4 hours of draw if submitting unprocessed whole blood.

Draw 4 full, light blue-top (citrate) tubes; and send citrated whole blood. Invert several times to mix blood. Forward unprocessed whole blood promptly at ambient temperature only. Do not refrigerate.

Note:  1. This test is only performed when patient’s PT is  above upper limit of PT normal range.

2. Indicate whole blood on request form.

3. Label specimens appropriately (whole blood).

Outpatient/Outreach Clients

Plasma-Frozen

Draw 3 full, light blue-top (citrate) tubes. Spin down, remove plasma, spin plasma again, and place citrated platelet-poor plasma in 4 plastic vials each containing 1 mL. (Glass vial is not acceptable.) Pour-off vials should be no more than 1/3 full. Send specimen frozen.

Note:  1. This test is only performed when patient’s PT is above upper limit of PT normal range.

2. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

3. Indicate plasma on request form.

4. Label specimens appropriately (plasma).

NOTE: If ordered in conjunction with APTT Mixing Study, only 4 aliquots required for both tests.