Specimen Collection Manual and Test Catalog

One (1) full 3.0 mL light blue top (3.2% sodium citrate) tube of whole blood.

Test may only be collected and performed at testing laboratories (see below). 

• If the patient’s hematocrit (HCT) is >55%, the volume of anticoagulant in the tube should be adjusted. Contact a performing location for special tube preparation to reduce the citrate in the collection tube. For those patients with HCT >65.4% see LAB3632 Stago Sodium Citrate Adjustment Chart for formula to determine amount of citrate removal required.
• When possible, use fresh venipuncture to collect blood to avoid activation of coagulation by tissue thromboplastin. Blood may be drawn from an indwelling catheter or vascular access device. Draw sample from a lumen that has not been heparinized or flush the line with 5 mL of saline and discard the first 10 mL of blood.
• Butterfly device collections, draw a discard tube first to remove air from collection tubing.
• Tubes should be >90% filled.
• Immediately mix gently after collection by inverting the tube end over end 5 to 6 times. Avoid vigorous mixing or additional inversion. Observe for the presence of clots. Recollect if fibrin clots observed.
• Hand-deliver to the laboratory immediately after collecting at ambient temperature.

Aliquoting of this test is not allowed as it is not appropriate for frozen testing.

Room temperature

2 hours

Clotted specimen, improperly filled tube, centrifuged specimen, stability exceeded, sample sent through pneumatic tube system, HCT > 55% without citrate adjusted tube.

Reference ranges verified using venous blood collected in sodium citrate tubes from normal adult (>18 years old) healthy donors not on anticoagulation. They do not reflect patients with different baseline coagulation values (examples: liver disease, pregnant women, children, hemophiliacs) or patient samples from a different source or collected in different specimen container.

Table 1: Reference Ranges

Figure 1. Typical TEG Tracing: 


Table 2: TEG 6s Parameters, Names, Definition of Parameter

TEG tracing available for real-time review using TEG Manager (requires GOAL course completion for website access).

Thromboelastography, Viscoelastography, Thromboelastogram

Global assessment of coagulation using whole blood that is typically utilized to guide transfusion in patients with trauma, recent cardiac surgery, liver transplantation, or surgical/ bleeding patients. There is no single ideal test to assess blood coagulation, and this should be used in conjunction with other coagulation studies and clinical findings. Limitations of the assay include:

1. Tissue factor, the initiator of the coagulation cascade, cannot be quantified by this test and abnormal levels cannot be detected.
2. Thromboplastin obtained from traumatic venipuncture or collection may falsely shorten values and a non-additive discard tube prior to collection is encouraged.
3.  This test does not assess the size of the injured vessel, blood flow characteristics, and local vessel wall biology, all of which affect blood coagulation.
4. Reference ranges do not reflect patients with atypical baseline coagulation values (examples: liver disease, pregnant women, children, hemophiliacs) or patient samples from arterial blood or collected in different specimen container. Therefore, parameter changes and transfusion therapy recommendations in these patient populations should not solely be based on numerical results, but TEG tracings and clinical state should also be considered.
   1. TEG has a sensitivity and specificity that may vary significantly in different populations (pediatrics, pregnant women, liver disease, hemophiliacs) and results in these populations should be interpreted with caution.
5. Anticoagulants and Antiplatelet agents may not be detected with TEG.
   1.  Warfarin is a commonly prescribed medication. In about half of patients on warfarin therapy, R-time may be normal in TEG. Poor correlation between TEG and INR is known. TEG should NOT be used to monitor warfarin therapy, instead an INR is still the gold standard for warfarin therapy monitoring.
   2. To assess platelet function for patients on a P2Y12 inhibitor (clopidogrel) or aspirin a platelet function assay (VerifyNow) is recommended.
   3. Direct Xa inhibitor will not typically prolong the R value and TEG results may appear normal. Check unfractionated heparin level. An abnormal unfractionated heparin level and normal CK R is suggestive of a direct Xa inhibitor.
6. To exclude venous thrombosis or pulmonary embolus in low-risk outpatients, a D-Dimer should be used.
7. Lysis 30 is not a sensitive marker for fibrinolysis and values <3% do not rule out hyperfibrinolysis.