Dilute Russell's viper venom time (dRVVT) is a laboratory test for lupus anticoagulant (LA). Russell's viper venom directly activates factor X in the patient's plasma. If the LA is present, the clotting time is prolonged because the LA binds up the phospholipid. Relatively common deficiencies or inhibitors of factors VII, VIII, IX, XI and XII do not affect the assay.

The dRVVT is thought to be more sensitive than the activated partial thromboplastin time (aPTT) for detection of lupus anticoagulants.

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Hematology