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Diagnostics Tests: Russell’s Viper Venom Clotting Time (RVVT)
Overview — What RVVT Is
Russell’s Viper Venom Clotting Time (RVVT) is a phospholipid-dependent coagulation test used to evaluate abnormalities in the clotting cascade.
The venom directly activates factor X, bypassing most of the intrinsic pathway. Because the test depends on phospholipids, it becomes prolonged when antiphospholipid antibodies interfere with the reaction.
A specialized form, the dilute Russell viper venom test (dRVVT), is used to increase sensitivity for lupus anticoagulant detection.
When RVVT Is Indicated
RVVT is used primarily in the detection of antiphospholipid antibodies, especially the lupus anticoagulant.
You should think of this test when:
RVVT is more specific than traditional PTT testing for diagnosing lupus anticoagulant.
Common Clinical Scenario
A typical clinical vignette that points toward lupus anticoagulant and therefore RVVT includes:
Overview — What RVVT Is
Russell’s Viper Venom Clotting Time (RVVT) is a phospholipid-dependent coagulation test used to evaluate abnormalities in the clotting cascade.
The venom directly activates factor X, bypassing most of the intrinsic pathway. Because the test depends on phospholipids, it becomes prolonged when antiphospholipid antibodies interfere with the reaction.
A specialized form, the dilute Russell viper venom test (dRVVT), is used to increase sensitivity for lupus anticoagulant detection.
When RVVT Is Indicated
RVVT is used primarily in the detection of antiphospholipid antibodies, especially the lupus anticoagulant.
You should think of this test when:
- A patient has a prolonged PTT
- The PTT does not correct with a mixing study (suggesting an inhibitor rather than a factor deficiency)
- You need confirmation that the inhibitor is specifically a lupus anticoagulant
RVVT is more specific than traditional PTT testing for diagnosing lupus anticoagulant.
Common Clinical Scenario
A typical clinical vignette that points toward lupus anticoagulant and therefore RVVT includes:
- A woman, often of childbearing age
- With or without known systemic lupus erythematosus (SLE)
- Recurrent spontaneous abortions (classic high-yield clue)
- History of unexplained venous or arterial thrombosis, such as:
- Deep vein thrombosis
- Pulmonary embolism
- Stroke in a young patient
- Or delivering an infant with congenital heart block (neonatal lupus can occur from anti-Ro/SSA, often coexisting with antiphospholipid antibodies)
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