Specimen Collection Requirements

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Specimen Collection Requirements Coagulation tests are extremely sensitive to methods of sample collection and processing. Results are a direct reflection of sample integrity. Temperature, time parameters, anticoagulant dilutional effects, mechanical agitation, hematocrit extremes and pH fluctuations affect samples for most testing. Follow NCCLS Reference Guidelines for Coagulation Sample Collection.  

Containers

The tubes should be Siliconized (to avoid activation of the coagulation system) and should contain sodium citrate. VacutainerR light blue top tube is usually used (There are three types: 5ml, 3ml and 2ml tubes). Sodium citrate (0.109M) at 3.2% is preferred.

Optimum Blood Sample Requirement

Generally, the ratio of blood to sodium citrate must be 9:1. Therefore, all VacutainerR blue top tubes must be filled to complete vacuum volume.

Minimum blood sample requirement: 

  • For a 5.0ml tube containing 0.5ml of 3.2% sodium citrate, the minimum blood sample requirement is 4.5ml 
  • For a 3.0ml tube containing 0.3ml of 3.2% sodium citrate, the minimum blood sample requirement is 2.7ml 
  • For a 2.0ml tube containing 0.2ml of 3.2% sodium citrate, the minimum blood sample requirement is 1.8ml

If the minimum blood sample requirement (less than 90%) is not met, the sample will be rejected and a new sample will be needed. 

Please note that the amount of sodium citrate needs to be adjusted if the patient is polycythemic (hematocrit >55%). If a patient has a hematocrit of >55%, call the special coag lab at (804) 628-5736 to make arrangements for adjusted tubes. 

 

Drawing Specimen

If coagulation testing is the only laboratory work is being drawn, first draw a plain red top tube to remove tissue fluid contamination. Discard this tube. Then draw blood into a buffered sodium citrate collection tube (blue top). Fill to proper level. (If other laboratory work is being drawn, use second or third tube for coagulation testing).  Invert gently six times to mix.  

Drawing Specimen from a catheter 
When drawing from an indwelling catheter, flush the line with 5ml of saline and discard the first 5ml of blood, before taking the coagulation sample.  Only draw blood from an indwelling catheter when a clean venipuncture is impossible. 

 

Specimen Processing 

For local specimen: Make sure the specimen gets to the lab as soon as possible (within 1-2 hours of collection), but certainly within 4 hours. See exceptions below under transport time.

For nonlocal specimen: Centrifuge the specimen within 30 minutes of collection in capped tube at 3500 rpms for 10 minutes. Specimen submitted must be platelet-free (platelet count <8,000/mm3). (It may be necessary to double spin too achieve this). Obtain a platelet count on the plasma to verify the count. Transfer platelet-free plasma with plastic pipette into plastic storage vial. Label appropriately, including the platelet count of the platelet-poor plasma. As specimen processing exceptions exist, please verify instructions under specific test reference. 

 

Transport Time 

All specimens must be received in the laboratory within 4 hours of collection.

There are, however, a few exceptions:

1. PLATELET AGGREGATION SPECIMEN must be received in the laboratory within two hours of collection.

2. For patients not on heparin, samples for PT testing may be accepted up to 24 hours after collection.

 

Test Scheduling 

There are some tests, which must be scheduled. These are: 

  • Platelet aggregation--Must not be spun and must not be refrigerated
  • PFA

Please call the coagulation laboratory to schedule these tests.  

 

Storage and Transportation 

Local specimens (within approximately 20 miles of MCV):

  1. Transport unspun specimen to MCV within 1-2 hours of collection. If spun and separated on site, send plasma specimen on ice.
  2. Telephone MCV Coagulation Special Studies Laboratories at  (804) 628-5736 to alert receiving.
  3. If Specimen cannot be transported within 2 hours, follow directives for nonlocal specimen handling.

Non Local Specimens (outside 20 miles of MCV):

  1. Freeze platelet-free specimen immediately at –20oC or less. 
  2. Ship in Styrofoam insulated container with enough space for 3-4 pounds of ice 
  3. Packaging
    • Add 3lb (minimum ice in one large chunk. Do not break up ice as exposure to air causes quick evaporation.
    • Place packing materials (i.e., Styrofoam “S” or newspaper) in the container to fill the rest of air space. 
    • Close container and seal the Styrofoam opening by taping completely. Tape will minimize exposure of content to air.
    • Place Styrofoam container in cardboard box, seal, and attach shipping label 
  4. Telephone MCV Coagulation Special Studies Laboratories at (804) 628-5736, to alert receiving. 
  5. Send to:
    Coagulation Special Studies Laboratory 
    Medical College of Virginia 
    Clinical support Building 665H  
    403 North 13th street  
    P. O. Box 980250  
    Richmond, Virginia 23298-0250

Minimum blood sample requirement: 

  • For a 5.0ml tube containing 0.5ml of 3.2% sodium citrate, the minimum blood sample requirement is 4.5ml 
  • For a 3.0ml tube containing 0.3ml of 3.2% sodium citrate, the minimum blood sample requirement is 2.7ml 
  • For a 2.0ml tube containing 0.2ml of 3.2% sodium citrate, the minimum blood sample requirement is 1.8ml

If the minimum blood sample requirement (less than 90%) is not met, the sample will be rejected and a new sample will be needed. 

Please note that the amount of sodium citrate needs to be adjusted if the patient is polycythemic (hematocrit >55%). If a patient has a hematocrit of >55%, call the special coag lab at (804) 628-5736 to make arrangements for adjusted tubes. 

 

Required Billing Information

We need adequate billing information to process claims to third party payers. The following information is essential for billing:

  • Address
  • Phone number
  • Social security number
  • Marital status
  • Guarantor’s name and phone number (if not patient)
  • Insurance policy/group number
  • Requesting physician’s name and Unique Physician Identification Number (UPIN)
  • ICD-9 diagnosis code

The following information is required for each request (failure to properly supply the following may result in delays in test analysis or in the rejection of the specimen):

Required Patient information

  • Full name 
  • Hospital number
  • Location (unit, clinic, etc.)
  • Attending physician 
  • Age, birth date, sex, race 
  • Billing account number

Required Test Information

  • Test(s) requested
  • Date and Time of specimen collection 
  • Identity of person collecting the specimen
  • Test Urgency level
  • Other information (i.e., specimen source, drug dosage information, other relevant history and comments)

Other Information When requested (such as for a Platelet Aggregation)

  • Clinical information
  • Menstrual history
  • Current medications
  • Pre-OP diagnosis 
  • Justification for request

For established outreach accounts, the account number should be included if the institution is to be billed . For any clarification, please contact the coagulation lab at (804) 628-5735, or client services (804) 828-PATH (828-7284); (800) 363-9234.