From the Guidelines
The DRVVT (Dilute Russell's Viper Venom Time) blood test is a crucial diagnostic tool for detecting lupus anticoagulant, a type of antibody associated with an increased risk of thrombosis, as recommended by the most recent guidelines from the ISTH-SSC Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies 1.
Overview of the Test
The DRVVT test measures the time it takes for blood to clot when a specific reagent derived from Russell's viper venom is added to a blood sample. This test is particularly useful in diagnosing antiphospholipid syndrome, a condition where the immune system mistakenly creates antibodies against certain blood proteins.
Clinical Applications
Doctors may order this test if a patient has unexplained blood clots, recurrent miscarriages, or certain autoimmune disorders like lupus. The test requires a simple blood draw and no special preparation is needed beforehand.
Interpretation of Results
Results are typically interpreted alongside other clotting tests, such as an LA-sensitive, activated partial thromboplastin time (APTT), to provide a comprehensive assessment of a patient's coagulation status, as suggested by the ISTH guidance recommendations 1.
Key Points to Consider
- The test is widely used in clinical laboratories and is believed to be specific for detecting lupus anticoagulant in patients at high risk of thrombosis 1.
- An international External Quality Assessment Programme has shown that dRVVT is the most robust test in detecting lupus anticoagulant 1.
- The ISTH-SSC Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies recommends using dRVVT as one of the assays of choice for testing for lupus anticoagulant 1.
From the Research
Definition of dRVVT Blood Test
- The dRVVT (dilute Russell's viper venom time) blood test is a coagulation test used to detect lupus anticoagulants, which are antibodies that can increase the risk of blood clots and other complications 2, 3, 4.
- The test measures the time it takes for blood to clot in the presence of a small amount of Russell's viper venom, which is a substance that activates the coagulation pathway 4.
Purpose of the dRVVT Blood Test
- The primary purpose of the dRVVT blood test is to diagnose lupus anticoagulants and antiphospholipid syndrome, a condition characterized by an increased risk of blood clots, recurrent fetal loss, and other clinical manifestations 2, 5.
- The test is also used to monitor patients with a history of blood clots or other thrombotic events, and to assess the effectiveness of anticoagulant therapy 2, 3.
How the dRVVT Blood Test is Performed
- The dRVVT blood test is typically performed in a laboratory setting, using a blood sample collected from a vein in the arm 4.
- The test involves several steps, including screening, mixing, and confirmatory studies, to detect the presence of lupus anticoagulants and to rule out other causes of abnormal coagulation results 4.
- The test may be affected by certain medications, such as heparin and vitamin K antagonists, which must be taken into account when interpreting the results 4, 6.
Interpretation of dRVVT Blood Test Results
- A prolonged dRVVT result may indicate the presence of lupus anticoagulants, which can increase the risk of blood clots and other complications 2, 3.
- The results of the dRVVT blood test must be interpreted in conjunction with other laboratory tests and clinical findings, such as a history of blood clots or other thrombotic events 2, 5.
- The test may need to be repeated to confirm the results and to monitor the effectiveness of anticoagulant therapy 2, 3.