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|Approval req'd?||Yes, for sample other than those from Cardio-Thoracic surgery must be approved BEFORE samples are collected.|
|Utilization Guidelines||This test is limited to Intra-operative samples from Cardio-Thoracic surgery. All others require approval BEFORE samples are collected.|
|Test code||TEG, HEPTEG|
|Performed by||Parnassus Hematology|
|In House Availability||Monday - Friday 0800-1530|
|Method||Clot formation and lysis|
|Collection Instructions||1. Check the expiration date on the label of the blue top vacutainer before drawing the patient.
2. For blood collection in a sodium citrate blue top, the tube must be filled to above the Minimum Fill Indicator on the tube. It is crucial to wait and allow the tube to stop filling before removing it from the needle.
3. With use of a butterfly needle, draw about 1 cc using a separate blue top to remove air from tubing, discard the first tube and then draw a second blue top tube filled to the full extent of the vacuum.
4. Tubes should not be filled past the Maximum Fill dashed line by either using a syringe or removing the tube cap.
For patients with Hct's ≥ 55% please contact Hematology (415-353-1747) to obtain blue top tubes with adjusted citrate volumes in order to maintain the proper citrate to plasma ratio for coagulation studies.
Specimens must be hand delivered to Hematology Lab M524. DO NOT SEND SPECIMEN IN PNEUMATIC TUBE.
This test can be performed either without (TEG) or with added heparinase (HEPTEG). TEG is typically utilized for patients on ventricular assist devices, and for hematology patients.HEPTEG is typically utilized for patients in the cardiac operating room, and for ECMO patients.
|Container type||Blue top (2.7 mL only)|
|Amount to Collect||2.7 mL blood|
|Sample type||Citrated whole blood|
|Preferred volume||2.7 mL blood|
|Min. Volume||2.7 mL blood|
|UCSF Rejection Criteria||Clotted samples or if stability period exceeded.|
|Processing notes||Deliver immediately to Hematology|
Note: Although pediatric normal ranges have not been extensively evaluated the results obtained from pediatric samples do not appear to differ appreciatively from adult samples.
|Synonyms||TEG; Thromboelastograph; Thromboelastogram; Thrombelastogram|
|Turn around times||< 90 minutes|
|Additional information||The thromboelastograph (TEG) may be useful in the diagnosis and monitoring of bleeding disorders, although its clinical utility is an area of continuing study. An internal study by the UCSF Clinical Labs, 2008, demonstrated that, as expected, TEG R, K, Angle, MA and LY30 values are each influenced by multiple characteristics of the blood sample under study.
Highlights and summary of our review of published literature, information from the manufacturer, and our internal analyses follow. For more detailed information, please contact Hematology at 353-1747, for referral to the head of the coagulation laboratory.
TEG may be useful for detecting certain types of platelet dysfunction, particularly acquired platelet dysfunction in association cardio-pulmonary bypass. However, the standard TEG assay performed at UCSF is NOT sensitive to the effects of aspirin and clopidogrel & the ability of TEG to detect the varied hereditary and acquired disorders of platelet function is NOT established. If detailed assessment of platelet function is needed, Platelet Aggregation (Test code: AGGR), should be ordered and scheduled (contact Hematology at 353-1747).
Decreased platelet function can cause a long K time, a decreased Angle, and a decreased MA. Decreased MA is considered the most specific sign of decreased platelet function. Nevertheless, a low MA can be caused by low levels of Fibrinogen as well as low levels of Factors II, V, and/or VII.
Post-cardiopulmonary bypass, the MA may be useful to guide platelet transfusion. When fibrinogen is >100 mg/dL AND PT is normal or only mildly prolonged (calculated INR<1.6), a low MA is consistent with acquired platelet dysfunction. Conversely, a normal MA in this setting suggests adequate platelet function.
The utility of the R, K, and Angle for transfusion decisions is not well established. Although a long R has been considered a possible indication for FFP transfusion, the internal UCSF studies did not validate R as a transfusion indication. Some patients with normal R values may have Factor levels that are inadequate for normal hemostasis, and therefore such patients might benefit from FFP. Further, some patients with significantly prolonged R values may have Factor levels adequate for normal hemostasis. The UCSF Transfusion Service recommends that clinical assessment be utilized with the PT to guide FFP transfusion, whereas clinical assessment and the Fibrinogen level is recommended for guiding transfusion of cryoprecipitate.
The LY30 (amount of clot lysis 30 minutes after peak clot) may be increased by low fibrinogen or by hyperfibrinolysis. The sensitivity and specificity of this assay for these conditions is not established. In the setting of post-cardiopulmonary bypass and microvascular bleeding, an LY30 >7.5% has been used to guide the application of antifibrinolytic therapy (reference: Br J Anesthesia 2004; 92:178). More generally, the manufacturer suggests that in the setting of hypocoagulability (long R, long K, low Angle, low MA), an antifibrinolytic might be useful when the LY30 is elevated. The manufacturer also states that "Anecdotal evidence suggests that LY30 >9% is the critical point at which therapeutic decisions should be considered." If the use of antifibrinolytics on the basis of TEG results is being contemplated, it may be useful to contact Hematology at 353-1747 to discuss the TEG results with the head of the coagulation laboratory.
TEG is available during normal daytime hours Monday-Friday for patients undergoing surgery that includes cardiopulmonary bypass. Pre-ordering/pre-accessioning of these samples is recommended. Contact Hematology at 353-1747 for the Senior Hematology Supervisor or the Coagulation Supervisor for instructions for pre-ordering/pre-accessioning of these TEG samples.
TEG can be requested by Adult or Pediatric Hematology, and by practitioners caring for adult patients with Ventricular Assist Devices or receiving Extracorporeal Membrane Oxygenation. Since TEG samples for patients undergoing cardiopulmonary bypass have priority, please contact hematology at 353-1747 to ensure that such TEG orders can be performed. Submitting such specimens early in the day (after 8 a.m.) is suggested to limit the possibility of the specimen being refused due to the use of the instrument to run TEG samples from the operating rooms.
If the patient is receiving heparin, has recently received heparin, or the sample is drawn through a heparinized line, order heparinase TEG (HEPTEG). If the patient has not received heparin, order regular TEG (TEG). If assessment for the adequacy of protamine reversal is desired, order HEPTEG and TEG.
The thrombelastograph has been cleared by the U.S. Food and Drug Administration as a medical device indicated for use with adult patients where an evaluation of their blood coagulation properties is desired. The use of TEG in pediatric patients has not been cleared by the FDA. The performance characteristics of the test were assessed by the Clinical Laboratories at the Medical Center at UC San Francisco
|CPT coding||85347, 85384, 85576, 85390|
|Last Updated||9/18/2012 2:27:09 PM|
If you have additional questions regarding this test, please call: 415-353-1667