Partial Thromboplastin Time, Activated
Test code: 763
CPT code(s): 85790
Methodology: Photo-Optical Clot Detection
Clinical Significance: The aPTT is a screening test that will detect deficiencies or inhibitors to the intrinsic (Factors VIII, IX, XI and XII) and common (Factors II, V, X and fibrinogen) pathway coagulation factors.
Limitations: Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: prolonged; Heparin (UFH or LMWH): prolonged; Dabigatran or Argatroban (Thrombin Inhibitors): prolonged; Rivaroxaban or Apixaban (Factor Xa Inhibitors): prolonged.
Alternative Name(s): APTT, PTT
Supply: #T04 - Light Blue 2.7 mL - One full unopened 3.2% sodium citrate (light blue-top) tube
Preferred Specimen: One full unopened 3.2% sodium citrate (light blue-top) tube
Alternate Specimen: 1 mL frozen plasma
Preferred Volume: 2.7 mL
Minimum Volume: 0.3 mL
Instructions:
Unopened light blue-top tube: Correct ratio of blood to citrate is critical. Do not overfill or underfill collection tube. Mix by inversion 4 times. For non-heparinized patients, maintain specimen at room temperature. Do not uncap. Stable 24 hours at room temperature.
Platelet-poor plasma: Centrifuge light blue-top tube 15 minutes at approximately 1500 g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Plasma must be free of platelets (<10,000/mcl). Freeze immediately and ship on dry ice.
Whole blood: The tubes should be at 100% +/- 10% fill volume in order to obtain the correct ratio.
Transport Container: 3.2% sodium citrate (light blue-top) tube
Transport Temperature: Room Temperature
Specimen Stability:
- Unopened light blue-top tube
- Room temperature: 24 hours
- Refrigerated: Unacceptable
- Frozen: Unacceptable
- Separated platelet-poor plasma
- Room Temperature: Unacceptable
- Refrigerated: Unacceptable
- Frozen: 14 days
Reject Criteria:
- Gross Hemolysis
- Grossly lipemic
- Improper blood to citrate ratio
- Clotted
- High hematocrits
- Thawed plasma received room temperature or refrigerated
For additional supply or collection device information, please contact DLO's Customer Service at (800) 891-2917, option 2.
The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.