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Immunology & Autoimmune
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The DRVVT Screen is a blood clotting test that measures how quickly your plasma forms a clot when exposed to a reagent made from Russell viper venom. This reagent activates part of the clotting pathway, making the test sensitive to substances that interfere with phospholipid dependent clotting steps.
It is primarily used to screen for a lupus anticoagulant, an autoimmune antibody that can slow clotting in the laboratory while being associated with clotting problems in the body. If the screen suggests an interference, the laboratory typically performs additional tests, such as a confirm assay and a mixing study, to clarify the cause.
Your clinician may order a DRVVT Screen if you have had unexplained blood clots, pregnancy losses, a prolonged clotting test on routine screening, or an autoimmune condition. It helps evaluate for antiphospholipid antibodies, particularly a lupus anticoagulant, which can influence treatment decisions and future risk assessment.
Results support the diagnosis of antiphospholipid syndrome when considered with your clinical history and other antibody tests. The test can also guide planning around surgery, hormone therapy, or long travel, and it can help determine whether anticoagulant medications or other factors are affecting clotting tests.
A result within the expected range makes a lupus anticoagulant less likely, though your healthcare team may still consider repeat testing if there is strong clinical suspicion. A prolonged screen suggests interference with phospholipid dependent clotting and often triggers reflex tests, such as a confirm assay that uses added phospholipid and a mixing study, to distinguish between an inhibitor and a factor deficiency.
Many conditions and medications can affect this test. Anticoagulants, acute illness, liver disease, and certain factor deficiencies can prolong the screen. If results are difficult to interpret, your clinician may recommend retesting when you are stable or off interfering drugs when it is safe to do so. Your final interpretation combines this test with confirmatory assays and your medical history.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Heparin, direct oral anticoagulants, and warfarin can prolong the DRVVT and complicate interpretation. Your clinician may time testing around dosing or consider drug neutralization strategies when appropriate and safe.
Underfilled citrate tubes, high hematocrit, delayed processing, or clotted samples can artifactually alter clotting times. Proper collection, prompt centrifugation, and frozen storage when needed help ensure reliable results.
Active thrombosis, infection, or inflammation can transiently affect clotting tests and antiphospholipid antibodies. Repeat testing after recovery is sometimes recommended to confirm persistence.
Reduced clotting factor levels from liver disease or congenital deficiencies can prolong the screen. Mixing studies and confirm assays help separate these from inhibitor effects like a lupus anticoagulant.
Physiologic changes and treatments used during pregnancy can influence clotting tests. When evaluating pregnancy complications, clinicians often interpret results alongside other antiphospholipid antibody tests and clinical history.
Autoimmune diseases such as systemic lupus erythematosus are associated with antiphospholipid antibodies. Test results are best interpreted in the context of your broader autoimmune profile and symptoms.
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