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Pathologist Interpretation: Prolonged Clotting Time

Path Consult: Coagulation, Coagulation Consultation for Pathology, Prolonged Clotting Time (PT or PTT)

Test Codes

EPIC: LAB1231246

Department

Coagulation

Instructions

• The Prolonged Clotting Time (PT or PTT) Panel includes a basic number of tests, however tests may be added or excluded at the pathologist’s discretion based on prior or concurrent laboratory results. The basic panel includes.
  • Inhibitor/Anticoagulant Screen
  • Thrombin Time
• It is expected that these panels will expedite work-up for complex coagulopathies or thrombotic risk factors. In addition, the pathologist will be able to order multiple tests on a single specimen, limiting the amount of blood to be drawn from the patient.

Specimen Collection Criteria

Collect: Five Light Blue-top 3.2% Sodium Citrate tubes.

• TUBES MUST BE FULL.
• A copy of the requisition must be sent with the specimen.

Physician Office/Draw Specimen Preparation

For optimal results, maintain whole blood Sodium Citrate specimens at room temperature (20-26°C or 68-78.8°F) prior to transport. Transport whole blood to the Laboratory within 4 hours of collection. If transport within 4 hours is not possible, the following procedure must be followed for accurate results:

1. Centrifuge the capped tube at 1500 x g for 15 minutes.

2. Transfer plasma with a plastic pipette into a screw cap, 5 ml, 75 x 13 mm, round base, polypropylene centrifuge tube, cap and centrifuge an and centrifuge an additional 15 minutes at 1500 x g to obtain platelet poor plasma (PPP) which has a platelet count less than 10 bil/L. Plasma with a platelet count of less than 10 bil/L is critical for accurate results.

3. Immediately remove only the top two-thirds of the PPP and transfer it into five plastic tubes.

4. Freeze (-20°C/-4°F or below) the PPP specimens immediately.

5. Transport frozen on DRY ICE. Specimen must remain frozen during transport.

Preparation for Courier Transport

Transport: Whole blood in Sodium Citrate at room temperature (20-26°C or 68-78.8°F), or plasma obtained through the process listed above, frozen (-20°C/-4°F or below).

Rejection Criteria

• Glass tubes and 3.8% Sodium Citrate tubes.
• Specimens that are clotted or grossly hemolyzed.
• Inappropriate specimen volume.
• Thawed or partially thawed specimens.

In-Lab Processing

Whole blood specimens must be processed as follows upon receipt in the Laboratory:

1. Centrifuge the capped tube at 1500 x g for 15 minutes.
2. Transfer plasma with a plastic pipette into a plastic polypropylene centrifuge tube, cap and centrifuge an additional 15 minutes at 1500 x g to obtain platelet poor plasma (PPP) which has a platelet count less than 10 bil/L. Plasma with a platelet count of less than 10 bil/L is critical for accurate results.
3. Immediately remove only the top two-thirds of the PPP and transfer it into five plastic tube.

4. Test or freeze specimen according to lab protocol.  

Storage

Specimen Stability for Testing:

Whole Blood (Sodium Citrate)
Room Temperature (20-26°C or 68-78.8°F): 4 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Platelet Poor Plasma (PPP)
Room Temperature (20-26°C or 68-78.8°F): Unacceptable
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): 30 days

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Coagulation Laboratory

Performed

Minimum once per week.
Results available in 3-5 days. Interpretation available within 5-7 business days. 

Reference Range

See individual tests listed for the appropriate reference ranges.

Inhibitor/Anticoagulant Screen, Thrombin Time.

Interpretation

An interpretative report will be included with each testing panel.

Clinical Utility

This panel should facilitate investigation of prolonged PT or PTT. Possible etiologies include factor deficiencies, factor inhibitors, lupus anticoagulant, consumptive coagulopathy, hypo/dysfibrinogenemia, etc. As with most complex laboratory testing, correlation with the clinical findings is necessary.

CPT Codes

85390 (additional codes depending on tests chosen by pathologist).

Contacts

Last Updated

8/15/2024