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Russell's Viper Venom Test
| Item | Value | ||||||
|---|---|---|---|---|---|---|---|
| Approval req'd? | No | ||||||
| Available Stat? | No | ||||||
| Utilization Guidelines | When lupus anticoagulant testing is requested, it is appropriate to perform BOTH the RVVT and Lupus Anticoagulant by HEXA tests. For this reason, both will be performed whenever either is ordered. In the uncommon circumstance that a provider wishes to perform only one of these tests, the hematology laboratory should be contacted at 353-1747 to request that only the single test be performed. | ||||||
| Test code | RVVTM | ||||||
| Performed by | Parnassus Hematology | ||||||
| In House Availability | Test run once per week (Tuesday) | ||||||
| Collection Instructions | When lupus anticoagulant testing is requested, it is appropriate to perform BOTH the RVVT and Lupus Anticoagulant by HEXA tests. For this reason, both will be performed whenever either is ordered. In the uncommon circumstance that a provider wishes to perform only one of these tests, the hematology laboratory should be contacted at 353-1747 to request that only the single test be performed. 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 (x3-1747) to obtain blue top tubes with adjusted citrate volumes in order to maintain the proper citrate to plasma ratio for coagulation studies. |
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| Container type | Blue top x2 filled to full extent of vacuum | ||||||
| Amount to Collect | 2.7 mL blood | ||||||
| Sample type | Citrated plasma | ||||||
| Preferred volume | 1 mL plasma | ||||||
| UCSF Rejection Criteria | Samples collected in outdated blue top vacutainer. Over-filled or under-filled tubes may be rejected | ||||||
| Processing notes | Within 1 hour of collection separate, centrifuge, and freeze 1.5 mL of plasma at -20C in a plastic tube. Note: If Lupus Anticoagulant ordered without further specification order both HEXA and RVVTM. |
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| Units | Seconds, Ratio | ||||||
| Normal range |
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| Synonyms | RVVT; RVVTD; LA; Lupus anticoagulant | ||||||
| Turn around times | 2-9 days | ||||||
| Additional information | When lupus anticoagulant testing is requested, it is appropriate to perform BOTH the RVVT and Lupus Anticoagulant by HEXA tests. For this reason, both will be performed whenever either is ordered. In the uncommon circumstance that a provider wishes to perform only one of these tests, the hematology laboratory should be contacted at 353-1747 to request that only the single test be performed. For detection of lupus anticoagulants, which by definition prolong a clotting time, are inhibitors, and are phospholipid dependent. Positives are automatically confirmed with an assay using a different reagent containing increased phospholipid content. An inhibitor screen is incorporated to exclude an abnormal result due to clotting factor deficiency. Persistent presence (> 3 months) of antiphospholipid antibodies has been associated with recurrent thrombosis syndromes. A review of testing performed on UCSF patients indicates that, of all patients diagnosed with Lupus Anticoagulants, approximately 50% are detected in both Hexagonal Phospholipid Neutralization and Russell's Viper Venom tests, 25% in only the Hexagonal Phospholipid Neutralization Test, and 25% in only the Russell's Viper Venom Test. Current guidelines suggest testing for lupus anticoagulant with two clot based tests (J Thromb Haemost 2009; 7: 1737-40). Lupus anticoagulant testing should be considered positive if one of the two tests gives a positive result. Positive test results must be interpreted in their clinical context if a diagnosis of antiphospholipid syndrome is being considered. J Thromb Haemost 2006; 4: 295-306 provides consensus guidelines for diagnosis of antiphospholipid syndrome. Testing for lupus anticoagulant in the presence of anticoagulant therapy (including warfarin, direct thrombin & direct factor 10a inhibitors, and supratherapeutic heparin) is not recommended due to possible interference with test results. Clinical correlation is advised as anticoagulation therapy may result in a false positive result. The presence of factor deficiencies or a factor specific inhibitor may also interfere with this assay. Rivaroxaban can cause false positive results in assays used to identify LA. Evaluation for a lupus anticoagulant, therefore, cannot be accurately performed in the presence of rivaroxaban. To monitor unfractionated heparin therapy in the presence of a lupus anticoagulant, Heparin Levels may be needed. |
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| LOINC code | 6303-2 | ||||||
| Last Updated | 11/8/2012 3:28:13 PM | ||||||
| Entry Number | 836 |
If you have additional questions regarding this test, please call: 415-353-1667