Specimen Requirements

Specimen must be tested within 4 hours of draw.

Container/Tube: Light blue-top (sodium citrate) tube

Specimen Volume: 4.5 mL (pediatric: 2.7 mL) of sodium citrate whole blood

Transport Temperature: Ambient only

Collection Instructions: Do not centrifuge. Do not refrigerate. 

Note: Medicare frequency limitations exist for this test in addition to diagnosis requirements. Click on link for list of medically necessary diagnoses: http://www.munsonhealthcare.org/medical-necessity.  See Advance Beneficiary Notice of Noncoverage (ABN) form in Special Instructions.

Special Instructions

1. Heparinized patients: Specimens must arrive within 45 minutes of draw. 

2. Inpatients: Specimen must arrive within 1 hour of draw.

3. Specimens collected offsite are discouraged as the criteria for completion of testing within 4 hours of draw may not be met due to transportation and processing.

3. Central line specimens:A physician’s order is required for any coagulation testing on central line specimens.

4. Premature infants: Proper blood/anticoagulant ratio is required for accurate testing. Special tubes with a decreased amount of anticoagulant may be prepared by Hematology to allow for a smaller amount of blood to be drawn.

If activated partial thromboplastin time testing is not completed within 4 hours of draw, plasma should be removed from the cells and frozen at -20° C for up to 2 weeks or -70° C for up to 6 months. A frost-free freezer should not be used. The PTT may be affected on specimens that have been frozen.